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|Formatting and coding information: |
| - Text in italics is marked with underscores as in _text_. |
| - Bold-face text is marked =text=. |
| - Superscript x and subscript x are represented as ^{x} and _{x},|
| respectively. |
| - sqrt(x) represents the square root of x. |
| - [oe] and [OE] represent the oe-ligatures. |
| - Greek letters are written between square brackets, as in [tau] |
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| - Overlined 1 is represented as [=1]. |
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|General remarks: |
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| refer to. |
| - In-line multiple line formulas have been changed to in-line |
| single-line formulas, with brackets added when needed. |
| - The Table of Contents has been corrected to conform to the text|
| rather than to the original Table of Contents. |
| - The table on operating costs of trains gives 'Other expenses |
| per square mile.' This has been changed to 'Per mile' the same |
| as the other expenses. |
| - The table on dimensions of farm and road locomotives gives the |
| diameter of the boiler shell as 30 feet, which seems unlikely. |
| - Feet are sometimes used as unit of area, both knots and knots |
| per hour as unit of speed. |
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| 'Desagulier' to 'Desaguliers' |
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THE INTERNATIONAL SCIENTIFIC SERIES.
VOLUME XXIV.
THE
INTERNATIONAL SCIENTIFIC SERIES.
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New York: D. APPLETON & CO., 1, 3, & 5 Bond Street.
[Illustration: THE GRECIAN IDEA OF THE STEAM-ENGINE.]
THE INTERNATIONAL SCIENTIFIC SERIES.
A HISTORY
OF THE
GROWTH OF THE STEAM-ENGINE.
BY
ROBERT H. THURSTON, A. M., C. E.,
PROFESSOR OF ENGINEERING STEVENS INSTITUTE OF TECHNOLOGY, PAST
PRESIDENT AMERICAN SOCIETY MECHANICAL ENGINEERS, MEMBER OF SOCIETY
OF CIVIL ENGINEERS, SOCIETE DES INGENIEURS CIVILS, VEREIN
DEUTSCHE INGENIEURE, OESTERREICHISCHER INGENIEUR- UND
ARCHITEKTEN-VEREIN; ASSOCIATE BRITISH INSTITUTION
OF NAVAL ARCHITECTS, ETC., ETC.
_SECOND REVISED EDITION._
NEW YORK:
D. APPLETON AND COMPANY,
1, 3, AND 5 BOND STREET.
1886.
COPYRIGHT, 1878, 1884,
BY ROBERT H. THURSTON.
PREFACE.
This little work embodies the more generally interesting portions of
lectures first written for delivery at the STEVENS INSTITUTE OF
TECHNOLOGY, in the winter of 1871-'72, to a mixed audience, composed,
however, principally of engineers by profession, and of mechanics; it
comprises, also, some material prepared for other occasions.
These lectures have been rewritten and considerably extended, and have
been given a form which is more appropriate to this method of
presentation of the subject. The account of the gradual development of
the philosophy of the steam-engine has been extended and considerably
changed, both in arrangement and in method. That part in which the
direction of improvement during the past history of the steam-engine,
the course which it is to-day taking, and the direction and limitation
of that improvement in the future, are traced, has been somewhat
modified to accord with the character of the revised work.
The author has consulted a large number of authors in the course of
his work, and is very greatly indebted to several earlier writers. Of
these, Stuart[1] is entitled to particular mention. His "History" is
the earliest deserving the name; and his "Anecdotes" are of
exceedingly great interest and of equally great historical value. The
artistic and curious little sketches at the end of each chapter are
from John Stuart, as are, usually, the drawings of the older forms of
engines.
[1] "History of the Steam-Engine," London, 1824. "Anecdotes of the
Steam-Engine," London, 1829.
Greenwood's excellent translation of Hero, as edited by Bennett
Woodcroft (London, 1851), can be consulted by those who are curious to
learn more of that interesting old Greek treatise.
Some valuable matter is from Farey,[2] who gives the most extended
account extant of Newcomen's and Watt's engines. The reader who
desires to know more of the life of Worcester, and more of the details
of his work, will find in the very complete biography of Dircks[3] all
that he can wish to learn of that great but unfortunate inventor.
Smiles's admirably written biography of Watt[4] gives an equally
interesting and complete account of the great mechanic and of his
partners; and Muirhead[5] furnishes us with a still more detailed
account of his inventions.
[2] "Treatise on the Steam-Engine," London, 1827.
[3] "Life, Times, and Scientific Labors of the Second Marquis of
Worcester," London, 1865.
[4] "Lives of Boulton and Watt," London, 1865.
[5] "Life of James Watt," D. Appleton & Co., New York, 1859.
"Mechanical Inventions of James Watt," London, 1854.
For an account of the life and work of John Elder, the great pioneer
in the introduction of the now standard double-cylinder, or
"compound," engine, the student can consult a little biographical
sketch by Prof. Rankine, published soon after the death of Elder.
The only published sketch of the history of the science of
thermo-dynamics, which plays so large a part of the philosophy of the
steam-engine, is that of Prof. Tait--a most valuable monograph.
The section of this work which treats of the causes and the extent of
losses of heat in the steam-engine, and of the methods available, or
possibly available, to reduce the amount of this now immense waste of
heat, is, in some respects, quite new, and is equally novel in the
method of its presentation. The portraits with which the book is well
furnished are believed to be authentic, and, it is hoped, will lend
interest, if not adding to the real value of the work.
Among other works which have been of great assistance to the author,
and will be found, perhaps, equally valuable to some of the readers of
this little treatise, are several to which reference has not been made
in the text. Among them the following are deserving of special
mention: Zeuner's "Waermetheorie," the treatises of Stewart and of
Maxwell, and McCulloch's "Mechanical Theory of Heat," a short but
thoroughly logical and exact mathematical treatise; Cotterill's
"Steam-Engine considered as a Heat-Engine," a more extended work on
the same subject, which will be found an excellent companion to, and
commentary upon, Rankine's "Steam-Engine and Prime Movers," which is
the standard treatise on the theory of the steam-engine. The works of
Bourne, of Holley, of Clarke, and of Forney, are standards on the
practical every-day matters of steam-engine construction and
management.
The author is almost daily in receipt of inquiries which indicate that
the above remarks will be of service to very many young engineers, as
well as to many to whom the steam-engine is of interest from a more
purely scientific point of view.
CONTENTS.
CHAPTER I.
THE STEAM-ENGINE AS A SIMPLE MACHINE.
PAGE
SECTION I.--THE PERIOD OF SPECULATION--FROM HERO TO WORCESTER,
B. C. 200 TO A. D. 1650 1
Introduction--the Importance of the Steam-Engine, 1; Hero and
his Treatise on Pneumatics, 4; Hero's Engines, B. C. 200, 8;
William of Malmesbury on Steam, A. D. 1150, 10; Hieronymus
Cardan on Steam and the Vacuum, 10; Malthesius on the Power of
Steam, A. D. 1571, 10; Jacob Besson on the Generation of Steam,
A. D. 1578, 11; Ramelli's Work on Machines, A. D. 1588, 11;
Leonardo da Vinci on the Steam-Gun, 12; Blasco de Garay's
Steamer, A. D. 1543, 12; Battista della Porta's Steam-Engine,
A. D. 1601, 13; Florence Rivault on the Force of Steam, A. D.
1608, 15; Solomon de Caus's Apparatus, A. D. 1615, 16; Giovanni
Branca's Steam-Engine, A. D. 1629, 16; David Ramseye's
Inventions, A. D. 1630, 17; Bishop John Wilkins's Schemes, A.
D. 1648, 18; Kircher's Apparatus, 19.
SECTION II.--THE PERIOD OF APPLICATION--WORCESTER, PAPIN, AND
SAVERY 19
Edward Somerset, Marquis of Worcester, A. D. 1663, 19;
Worcester's Steam Pumping-Engines, 21; Jean Hautefeuille's
Alcohol and Gunpowder Engines, A. D. 1678, 24; Huyghens's
Gunpowder-Engine, A. D. 1680, 25; Invention in Great Britain,
26; Sir Samuel Morland, A. D. 1683, 27; Thomas Savery and his
Engine, A. D. 1698, 31; Desaguliers's Savery Engines, A. D.
1718, 41; Denys Papin and his Work, A. D. 1675, 45; Papin's
Engines, A. D. 1685-1695, 50; Papin's Steam-Boilers, 51.
CHAPTER II.
THE STEAM-ENGINE AS A TRAIN OF MECHANISM.
THE MODERN TYPE AS DEVELOPED BY NEWCOMEN, BEIGHTON, AND SMEATON 55
Defects of the Savery Engine, 55; Thomas Newcomen, A. D. 1705,
57; the Newcomen Steam Pumping-Engine, 59; Advantages of
Newcomen's Engine, 60; Potter's and Beighton's Improvements, A.
D. 1713-'18, 61; Smeaton's Newcomen Engines, A. D. 1775, 64;
Operation of the Newcomen Engine, 65; Power and Economy of the
Engine, 69; Introduction of the Newcomen Engine, 70.
CHAPTER III.
THE DEVELOPMENT OF THE MODERN STEAM-ENGINE. JAMES WATT AND HIS
CONTEMPORARIES.
SECTION I.--JAMES WATT AND HIS INVENTIONS 79
James Watt, his Birth and Parentage, 79; his Standing in
School, 81; he learns his Trade in London, 81; Return to
Scotland and Settlement in Glasgow, 82; the Newcomen Engine
Model, 83; Discovery of Latent Heat, 84; Sources of Loss in the
Newcomen Engine, 85; Facts experimentally determined by Watt,
86; Invention of the Separate Condenser, 87; the Steam-Jacket
and other Improvements, 90; Connection with Dr. Roebuck, 91;
Watt meets Boulton, 93; Matthew Boulton, 93; Boulton's
Establishment at Soho, 95; the Partnership of Boulton and Watt,
97; the Kinneil Engine, 97; Watt's Patent of 1769, 98; Work of
Boulton and Watt, 101; the Rotative Engine, 103; the Patent of
1781, 104; the Expansion of Steam--its Economy, 105; the
Double-Acting Engine, 110; the "Compound" Engine, 110; the
Steam-Hammer, 111; Parallel Motions, the Counter, 112; the
Throttle-Valve and Governor, 114; Steam, Vacuum, and Water
Gauges, 116; Boulton & Watt's Mill-Engine, 118; the Albion Mill
and its Engine, 119; the Steam-Engine Indicator, 123; Watt in
Social Life, 125; Discovery of the Composition of Water, 126;
Death of James Watt, 128; Memorials and Souvenirs, 128.
SECTION II.--THE CONTEMPORARIES OF JAMES WATT 132
William Murdoch and his Work, 132; Invention of Gas-Lighting,
134; Jonathan Hornblower and the Compound Engine, 135; Causes
of the Failure of Hornblower, 137; William Bull and Richard
Trevithick, 138; Edward Cartwright and his Engine, 140.
CHAPTER IV.
THE MODERN STEAM-ENGINE.
THE SECOND PERIOD OF APPLICATION--1800-1850--STEAM-LOCOMOTION
ON RAILROADS 144
Introduction, 144; the Non-Condensing Engine and the
Locomotive, 147; Newton's Locomotive, 1680, 149; Nathan Read's
Steam-Carriage, 150; Cugnot's Steam-Carriage, 1769, 151; the
Model Steam-Carriage of Watt and Murdoch, 1784, 153; Oliver
Evans and his Plans, 1786, 153; Evans's Oruktor Amphibolis,
1804, 157; Richard Trevithick's Steam-Carriage, 1802, 159;
Steam-Carriages of Griffiths and others, 160; Steam-Carriages
of Goldsworthy Gurney, 1827, 161; Steam-Carriages of Walter
Hancock, 1831, 165; Reports to the House of Commons, 1831, 170;
the Introduction of the Railroad, 172; Richard Trevithick's
Locomotives, 1804, 174; John Stevens and the Railroad, 1812,
178; William Hedley's Locomotives, 1812, 181; George
Stephenson, 183; Stephenson's Killingworth Engine, 1813, 186;
Stephenson's Second Locomotive, 1815, 187; Stephenson's
Safety-Lamp, 1815, 187; Robert Stephenson & Co., 1824, 190; the
Stockton & Darlington Engine, 1825, 191; the Liverpool &
Manchester Railroad, 1826, 193; Trial of Competing Engines at
Rainhill, 1829, 195; the Rocket and the Novelty, 198;
Atmospheric Railways, 201; Character of George Stephenson,
204; the Locomotive of 1833, 204; Introduction of Railroads in
Europe, 206; Introduction of Railroads in the United States,
207; John Stevens's Experimental Railroad, 1825, 207; Horatio
Allen and the "Stourbridge Lion," 1829, 208; Peter Cooper's
Engine, 1829, 209; E. L. Miller and the S. C. Railroad, 1830,
210; the "American" Type of Engine of John B. Jervis, 1832,
212; Robert L. Stevens and the T-rail, 1830, 214; Matthias W.
Baldwin and his Engine, 1831, 215; Robert Stephenson on the
Growth of the Locomotive, 220.
CHAPTER V.
THE MODERN STEAM-ENGINE.
THE SECOND PERIOD OF APPLICATION--1800-1850 (CONTINUED)--THE
STEAM-ENGINE APPLIED TO SHIP-PROPULSION 221
Introduction, 221; Ancient Prophecies, 223; the Earliest
Paddle-Wheel, 223; Blasco de Garay's Steam-Vessel, 1543, 224;
Experiments of Dionysius Papin, 1707, 214; Jonathan Hulls's
Steamer, 1736, 225; Bernouilli and Gauthier, 228; William
Henry, 1782, 230; the Comte d'Auxiron, 1772, 232; the Marquis
de Jouffroy, 1776, 233; James Rumsey, 1774, 234; John Fitch,
1785, 285; Fitch's Experiments on the Delaware, 1787, 237;
Fitch's Experiments at New York, 1796, 240; the Prophecy of
John Fitch, 241; Patrick Miller, 1786-'87, 241; Samuel Morey,
1793, 243; Nathan Read, 1788, 244; Dundas and Symmington, 1801,
246; Henry Bell and the Comet, 1811, 248; Nicholas Roosevelt,
1798, 250; Robert Fulton, 1802, 251; Fulton's Torpedo-Vessels,
1801, 252; Fulton's First Steamboat, 1803, 253; the Clermont,
1807, 257; Voyage of the Clermont to Albany, 259; Fulton's
Later Steamboats, 260; Fulton's War-Steamer Fulton the First,
1815, 261; Oliver Evans, 1804, 263; John Stevens's
Screw-Steamer, 1804, 264; Stevens's Steam-Boilers, 1804, 264;
Stevens's Iron-Clad, 1812, 268; Robert L. Stevens's
Improvements, 270; the "Stevens Cut-off," 1841, 276; the
Stevens Iron-Clad, 1837, 277; Robert L. Thurston and John
Babcock, 1821, 280; James P. Allaire and the Messrs. Copeland,
281; Erastus W. Smith's Compound Engine, 283; Steam-Navigation
on Western Rivers, 1811, 283; Ocean Steam-Navigation, 1808,
285; the Savannah, 1819, 286; the Sirius and the Great Western,
1838, 289; the Cunard Line, 1840, 290; the Collins Line, 1851,
291; the Side-Lever Engine, 292; Introduction of
Screw-Steamers, 293; John Ericsson's Screw-Vessels, 1836, 294;
Francis Pettit Smith, 1837, 296; the Princeton, 1841, 297;
Advantages of the Screw, 299; the Screw on the Ocean, 300;
Obstacles to Improvement, 301; Changes in Engine-Construction,
302; Conclusion, 303.
CHAPTER VI.
THE STEAM-ENGINE OF TO-DAY.
THE PERIOD OF REFINEMENT--1850 TO DATE 303
Condition of the Steam-Engine at this Time, 303; the Later
Development of the Engine, 304; Stationary Steam-Engines, 307;
the Steam-Engine for Small Powers, 307; the Horizontal Engine
with Meyer Valve-Gear, 311; the Allen Engine, 314; its
Performance, 316; the Detachable Valve-Gear, 316; the Sickels
Cut-off, 317; Expansion adjusted by the Governor, 318; the
Corliss Engine, 319; the Greene Engine, 321; Perkins's
Experiments, 323; Dr. Alban's Work, 325; the Perkins Compound
Engine, 327; the Modern Pumping-Engine, 328; the Cornish
Engine, 328; the Steam-Pump, 331; the Worthington
Pumping-Engine, 333; the Compound Beam and Crank Engine, 335;
the Leavitt Pumping-Engine, 336; the Stationary Steam-Boiler,
338; "Sectional" Steam-Boilers, 343; "Performance" of Boilers,
344.
SECTION II.--PORTABLE AND LOCOMOTIVE ENGINES. 347
The Semi-Portable Engine, 348; Performance of Portable Engines,
350; their Efficiency, 352; the Hoadley Engine, 354; the Mills
Farm and Road Engine, 356; Fisher's Steam-Carriage, 356;
Performance of Road-Engines, 357; Trial of Road-Locomotives by
the Author, 358; Conclusions, 358; the Steam Fire-Engine, 360;
the Rotary Steam-Engine and Pump, 365; the Modern Locomotive,
368; Dimensions and Performance, 373; Compound Engines for
Locomotives, 376; Extent of Modern Railroads, 378;
SECTION III.--MARINE ENGINES. 379
The Modern Marine Engine, 379; the American Beam Engine, 379;
the Oscillating Engine and Feathering Wheel, 381; the two
"Rhode Islands," 382; River-Boat Engines on the Mississippi,
384; Steam Launches and Yachts, 386; Marine Screw-Engines, 389;
the Marine Compound Engine, 390; its Introduction by John Elder
and others, 393; Comparison with the Single-Cylinder Engine,
395; its Advantages, 396; the Surface Condenser, 397; Weight of
Machinery, 398; Marine Engine Performance, 398; Relative
Economy of Simple and Compound Engines, 399; the
Screw-Propeller, 399; Chain-Propulsion, or Wire-Rope Towage,
402; Marine Steam-Boilers, 403; the Modern Steamship, 405;
Examples of Merchant Steamers, 406; Naval
Steamers--Classification, 409; Examples of Iron-Clad Steamers,
412; Power of the Marine Engine, 415; Conclusion, 417.
CHAPTER VII.
THE PHILOSOPHY OF THE STEAM-ENGINE.
THE HISTORY OF ITS GROWTH; ENERGETICS AND THERMO-DYNAMICS 419
General Outline, 419; Origin of its Power, 419; Scientific
Principles involved in its Operation, 420; the Beginnings of
Modern Science, 421; the Alexandrian Museum, 422; the
Aristotelian Philosophy, 424; the Middle Ages, 426; Galileo's
Work, 428; Da Vinci and Stevinus, 429; Kepler, Hooke, and
Huyghens, 429; Newton and the New Mechanical Philosophy, 430;
the Inception of the Science of Energetics, 483; the
Persistence of Energy, 433; Rumford's Experiments, 434;
Fourier, Carnot, Seguin, 437; Mayer and the Mechanical
Equivalent of Heat, 438; Joule's Determination of its Value,
438; Prof. Rankine's Investigations, 442; Clausius-Thompson's
Principles, 444; Experimental Work of Boyle, Black, and Watt,
446; Robison's, Dalton's, Ure's, and Biot's Study of Pressures
and Temperatures of Steam, 447; Arago's and Dulong's
Researches, 447; Franklin Institute Investigation, 447;
Cagniard de la Tour--Faraday, 447; Dr. Andrews and the Critical
Point, 448; Donny's and Dufour's Researches, 448; Regnault's
Determination of Temperatures and Pressures of Steam, 449;
Hirn's Experiments, 450; Resume of the Philosophy of the
Steam-Engine, 451; Energy--Definitions and Principles, 451; its
Measure, 452; the Laws of Energetics, 453; Thermo-dynamics,
453; its Beginnings, 454; its Laws, 454; Rankine's General
Equation, 455; Rankine's Treatise on the Theory of
Heat-Engines, 456; Merits of the Great Philosopher, 456.
CHAPTER VIII.
THE PHILOSOPHY OF THE STEAM-ENGINE.
ITS APPLICATION; ITS TEACHINGS RESPECTING THE CONSTRUCTION OF
THE ENGINE AND ITS IMPROVEMENT 457
Origin of all Energy, 457; the Progress of Energy through
Boiler and Engine, 458; Conditions of Heat-Development in the
Boiler, 458; the Steam in the Engine, 458; the Expansion of
Steam, 459; Conditions of Heat-Utilization, 460; Loss of Power
in the Engine, 462; Conditions affecting the Design of the
Steam-Engine, 466; the Problem stated, 466; Economy as affected
by Pressure and Temperature, 467; Changes which have already
occurred, 468; Direction of Changes now in Progress, 470;
Summary of Facts, 471; Characteristics of a Good Steam-Engine,
473; Principles of Steam-Boiler Construction, 476.
LIST OF ILLUSTRATIONS.
FRONTISPIECE: The Grecian Idea of the Steam-Engine.
FIG. PAGE
1. Opening Temple-Doors by Steam, B. C. 200 6
2. Steam Fountain, B. C. 200 7
3. Hero's Engine, B. C. 200 8
4. Porta's Apparatus, A. D. 1601 14
5. De Caus's Apparatus, A. D. 1605 15
6. Branca's Steam-Engine, A. D. 1629 17
7. Worcester's Steam-Fountain, A. D. 1650 21
8. Worcester's Engine, A. D. 1665 22
9. Wall of Raglan Castle 22
10. Huyghens's Engine, 1680 26
11. Savery's Model, 1698 34
12. Savery's Engine, 1698 35
13. Savery's Engine, A. D. 1702 37
14. Papin's Two-Way Cock 42
15. Engine Built by Desaguliers in 1718 43
16. Papin's Digester, 1680 48
17. Papin's Engine 50
18. Papin's Engine and Water-Wheel, A. D. 1707 53
19. Newcomen's Engine, A. D. 1705 59
20. Beighton's Valve-Gear, A. D. 1718 63
21. Smeaton's Newcomen Engine 65
22. Boiler of Newcomen Engine, 1763 67
23. Smeaton's Portable-Engine Boiler, 1765 73
24. The Newcomen Model 84
25. Watt's Experiment 89
26. Watt's Engine, 1774 98
27. Watt's Engine, 1781 104
28. Expansion of Steam 108
29. The Governor 115
30. Mercury Steam-Gauge and Glass Water-Gauge 117
31. Boulton & Watt's Double-Acting Engine, 1784 119
32. Valve-Gear of the Albion Mills Engine 121
33. Watt's Half-Trunk Engine, 1784 122
34. The Watt Hammer, 1784 123
35. James Watt's Workshop 129
36. Murdoch's Oscillating Engine, 1785 134
37. Hornblower's Compound Engine, 1781 136
38. Bull's Pumping-Engine, 1798 139
39. Cartwright's Engine, 1798 141
40. The First Railroad-Car, 1825 144
41. Leupold's Engine, 1720 148
42. Newton's Steam-Carriage, 1680 149
43. Read's Steam-Carriage, 1790 150
44. Cugnot's Steam-Carriage, 1770 151
45. Murdoch's Model, 1784 153
46. Evans's Non-Condensing Engine, 1800 156
47. Evans's "Oruktor Amphibolis," 1804 157
48. Gurney's Steam-Carriage 163
49. Hancock's "Autopsy", 1833 168
50. Trevithick's Locomotive, 1804 175
51. Stephenson's Locomotive of 1815. Section 187
52. Stephenson's No. 1 Engine, 1825 191
53. Opening of the Stockton and Darlington Railroad, 1815 192
54. The "Novelty," 1829 197
55. The "Rocket," 1829 198
56. The Atmospheric Railroad 202
57. Stephenson's Locomotive, 1833 203
58. The Stephenson Valve-Gear, 1833 206
59. The "Atlantic," 1832 210
60. The "Best Friend," 1830 211
61. The "West Point," 1831 212
62. The "South Carolina," 1831 213
63. The "Stevens" Rail and Enlarged Section 215
64. "Old Ironsides," 1832 216
65. The "E. L. Miller," 1834 217
66. Hulls's Steamboat, 1736 226
67. Fitch's Model, 1785 236
68. Fitch & Voight's Boiler, 1787 238
69. Fitch's First Boat, 1787 238
70. John Fitch, 1788 239
71. John Fitch, 1796 240
72. Miller, Taylor & Symmington, 1788 242
73. Read's Boiler in Section, 1788 245
74. Read's Multi-Tubular Boiler, 1788 245
75. The "Charlotte Dundas," 1801 247
76. The "Comet," 1812 248
77. Fulton's Experiments 253
78. Fulton's Table of Resistances 254
79. Barlow's Water-Tube Boiler, 1793 256
80. The "Clermont," 1807 258
81. Engine of the "Clermont," 1808 258
82. Launch of the "Fulton the First," 1804 262
83. Section of Steam-Boiler, 1804 264
84. Engine, Boiler, and Screw-Propellers used by Stevens, 1804 265
85. Stevens's Screw Steamer, 1804 265
86. John Stevens's Twin-Screw Steamer, 1805 269
87. The Feathering Paddle-Wheel 272
88. The "North America" and "Albany," 1827-'30 274
89. Stevens's Return Tubular Boiler, 1832 275
90. Stevens's Valve-Motion 276
91. The "Atlantic," 1851 290
92. The Side-Lever Engine, 1849 291
93. Vertical Stationary Steam-Engine 308
94. Vertical Stationary Steam-Engine. Section 309
95. Horizontal Stationary Steam-Engine 312
96. Horizontal Stationary Steam-Engine 313
97. Corliss Engine 319
98. Corliss Engine Valve-Motion 320
99. Greene Engine 321
100. Thurston's Greene-Engine Valve-Gear 322
101. Cornish Pumping-Engine, 1880 329
102. Steam-Pump 331
103. The Worthington Pumping-Engine, 1876. Section 333
104. The Worthington Pumping-Engine 334
105. Double-Cylinder Pumping-Engine, 1878 335
106. The Lawrence Water-Works Engine 336
107. The Leavitt Pumping-Engine 337
108. Babcock & Wilcox's Vertical Boiler 341
109. Stationary "Locomotive" Boiler 342
110. Galloway Tube 343
111. Harrison's Sectional Boiler 345
112. Babcock and Wilcox's Sectional Boiler 346
113. Root Sectional Boiler 347
114. Semi-Portable Engine, 1878 348
115. Semi-Portable Engine, 1878 349
116. The Portable Steam-Engine, 1878 354
117. The Thrashers' Road-Engine, 1878 355
118. Fisher's Steam-Carriage 356
119. Road and Farm Locomotive 357
120. The Latta Steam Fire-Engine 361
121. The Amoskeag Engine. Section 363
122. The Silsby Rotary Steam Fire-Engine 364
123. Rotary Steam-Engine 365
124. Rotary Pump 366
125. Tank Engine, New York Elevated Railroad 369
126. Forney's Tank-Locomotive 370
127. British Express Engine 371
128. The Baldwin Locomotive. Section 372
129. The American Type of Express Engine, 1878 374
130. Beam Engine 380
131. Oscillating Steam-Engine and Feathering Paddle-Wheel 381
132. The Two "Rhode Islands," 1836-1876 383
133. A Mississippi Steamboat 384
134. Steam-Launch, New York Steam-Power Company 386
135. Launch-Engine 387
136. Horizontal, Direct-acting Naval Screw Engine 389
137. Compound Marine Engine. Side Elevation 390
138. Compound Marine Engine. Front Elevation and Section 391
139. Screw-Propeller 400
140. Tug-Boat Screw 401
141. Hirsch Screw 401
142. Marine Fire-Tubular Boiler. Section 403
143. Marine High-Pressure Boiler. Section 404
144. The Modern Steamship 407
145. Modern Iron-Clads 410
146. The "Great Eastern" 415
147. The "Great Eastern" at Sea 416
PORTRAITS.
NO. PAGE
1. Edward Somerset, the Second Marquis of Worcester 20
2. Thomas Savery 31
3. Denys Papin 46
4. James Watt 80
5. Matthew Boulton 94
6. Oliver Evans 154
7. Richard Trevithick 174
8. Colonel John Stevens 178
9. George Stephenson 183
10. Robert Fulton 251
11. Robert L. Stevens 270
12. John Elder 393
13. Benjamin Thompson, Count Rumford 434
14. James Prescott Joule 439
15. Prof. W. J. M. Rankine 443
["A Machine, receiving at distant times and from many hands new
combinations and improvements, and becoming at last of signal
benefit to mankind, may be compared to a rivulet swelled in its
course by tributary streams, until it rolls along a majestic river,
enriching, in its progress, provinces and kingdoms.
"In retracing the current, too, from where it mingles with the
ocean, the pretensions of even ample subsidiary streams are merged
in our admiration of the master-flood, glorying, as it were, in its
expansion. But as we continue to ascend, those waters which, nearer
the sea, would have been disregarded as unimportant, begin to rival
in magnitude and share our attention with the parent stream; until,
at length, on our approaching the fountains of the river, it appears
trickling from the rock, or oozing from among the flowers of the
valley.
"So, also, in developing the rise of a machine, a coarse instrument
or a toy may be recognized as the germ of that production of
mechanical genius, whose power and usefulness have stimulated our
curiosity to mark its changes and to trace its origin. The same
feelings of reverential gratitude which attached holiness to the
spot whence mighty rivers sprang, also clothed with divinity, and
raised altars in honor of, inventors of the saw, the plough, the
potter's wheel, and the loom."--STUART.]
THE GROWTH OF THE STEAM-ENGINE.
CHAPTER I.
_THE STEAM-ENGINE AS A SIMPLE MACHINE._
SECTION I.--THE PERIOD OF SPECULATION--FROM HERO TO WORCESTER, B. C.
200 TO A. D. 1650.
One of the greatest of modern philosophers--the founder of that system
of scientific philosophy which traces the processes of evolution in
every department, whether physical or intellectual--has devoted a
chapter of his "First Principles" of the new system to the
consideration of the multiplication of the effects of the various
forces, social and other, which are continually modifying this
wonderful and mysterious universe of which we form a part. Herbert
Spencer, himself an engineer, there traces the wide-spreading,
never-ceasing influences of new inventions, of the introduction of new
forms of mechanism, and of the growth of industrial organization, with
a clearness and a conciseness which are so eminently characteristic of
his style. His illustration of this idea by reference to the manifold
effects of the introduction of steam-power and its latest embodiment,
the locomotive-engine, is one of the strongest passages in his work.
The power of the steam-engine, and its inconceivable importance as an
agent of civilization, has always been a favorite theme with
philosophers and historians as well as poets. As Religion has always
been, and still is, the great _moral_ agent in civilizing the world,
and as Science is the great _intellectual_ promoter of civilization,
so the Steam-Engine is, in modern times, the most important _physical_
agent in that great work.
It would be superfluous to attempt to enumerate the benefits which it
has conferred upon the human race, for such an enumeration would
include an addition to every comfort and the creation of almost every
luxury that we now enjoy. The wonderful progress of the present
century is, in a very great degree, due to the invention and
improvement of the steam-engine, and to the ingenious application of
its power to kinds of work that formerly taxed the physical energies
of the human race. We cannot examine the methods and processes of any
branch of industry without discovering, somewhere, the assistance and
support of this wonderful machine. Relieving mankind from manual toil,
it has left to the intellect the privilege of directing the power,
formerly absorbed in physical labor, into other and more profitable
channels. The intelligence which has thus conquered the powers of
Nature, now finds itself free to do head-work; the force formerly
utilized in the carrying of water and the hewing of wood, is now
expended in the God-like work of THOUGHT. What, then, can be more
interesting than to trace the history of the growth of this wonderful
machine?--the greatest among the many great creations of one of God's
most beneficent gifts to man--the power of invention.
While following the records and traditions which relate to the
steam-engine, I propose to call attention to the fact that its history
illustrates the very important truth: _Great inventions are never, and
great discoveries are seldom, the work of any one mind_. Every great
invention is really either an aggregation of minor inventions, or the
final step of a progression. It is not a creation, but _a growth_--as
truly so as is that of the trees in the forest. Hence, the same
invention is frequently brought out in several countries, and by
several individuals, simultaneously. Frequently an important invention
is made before the world is ready to receive it, and the unhappy
inventor is taught, by his failure, that it is as unfortunate to be in
advance of his age as to be behind it. Inventions only become
successful when they are not only needed, but when mankind is so far
advanced in intelligence as to appreciate and to express the necessity
for them, and to at once make use of them.
More than half a century ago, an able New England writer, in a
communication to an English engineering periodical, described the new
machinery which was built at Newport, R. I., by John Babcock and
Robert L. Thurston, for one of the first steamboats that ever ran
between that city and New York. He prefaced his description with a
frequently-quoted remark to the effect that, as Minerva sprang, mature
in mind, in full stature of body, and completely armed, from the head
of Jupiter, so the steam-engine came forth, perfect at its birth, from
the brain of James Watt. But we shall see, as we examine the records
of its history, that, although James Watt was _an_ inventor, and
probably the greatest of the inventors of the steam-engine, he was
still but one of the many men who have aided in perfecting it, and who
have now made us so familiar with it, and its tremendous power and its
facile adaptations, that we have almost ceased to admire it, or to
wonder at the workings of the still more admirable intelligence that
has so far perfected it.
Twenty-one centuries ago, the political power of Greece was broken,
although Grecian civilization had risen to its zenith. Rome, ruder
than her polished neighbor, was growing continually stronger, and was
rapidly gaining territory by absorbing weaker states. Egypt, older in
civilization than either Greece or Rome, fell but two centuries later
before the assault of the younger states, and became a Roman province.
Her principal city was at this time Alexandria, founded by the great
soldier whose name it bears, when in the full tide of his prosperity.
It had now become a great and prosperous city, the centre of the
commerce of the world, the home of students and of learned men, and
its population was the wealthiest and most civilized of the then known
world.
It is among the relics of that ancient Egyptian civilization that we
find the first records in the early history of the steam-engine. In
Alexandria, the home of Euclid, the great geometrician, and possibly
contemporary with that talented engineer and mathematician,
Archimedes, a learned writer, called Hero, produced a manuscript which
he entitled "Spiritalia seu Pneumatica."
It is quite uncertain whether Hero was the inventor of any number of
the contrivances described in his work. It is most probable that the
apparatus described are principally devices which had either been long
known, or which were invented by Ctesibius, an inventor who was famous
for the number and ingenuity of the hydraulic and pneumatic machines
that he devised. Hero states, in his Introduction, his intention to
describe existing machines and earlier inventions, and to add his own.
Nothing in the text, however, indicates to whom the several machines
are to be ascribed.[6]
[6] The British Museum contains four manuscript copies of Hero's
"Pneumatics," which were written in the fifteenth and sixteenth
centuries. These manuscripts have been examined with great care, and
a translation from them prepared by Prof. J. G. Greenwood, and
published at the desire of Mr. Bennett Woodcroft, the author of a
valuable little treatise on "Steam Navigation." This is, so far as
the author is aware, the only existing English translation of any
portion of Hero's works.
The first part of Hero's work is devoted to applications of the
syphon. The 11th proposition is the first application of heat to
produce motion of fluids.
An altar and its pedestal are hollow and air-tight. A liquid is poured
into the pedestal, and a pipe inserted, of which the lower end passes
beneath the surface of the liquid, and the upper extremity leads
through a figure standing at the altar, and terminates in a vessel
inverted above this altar. When a fire is made on the altar, the heat
produced expands the confined air, and the liquid is driven up the
tube, issuing from the vessel in the hand of the figure standing by
the altar, which thus seems to be offering a libation. This toy
embodies the essential principle of all modern heat-engines--the
change of energy from the form known as heat-energy into mechanical
energy, or work. It is not at all improbable that this prototype of
the modern wonder-working machine may have been known centuries before
the time of Hero.
Many forms of hydraulic apparatus, including the hand fire-engine,
which is familiar to us, and is still used in many of our smaller
cities, are described, the greater number of which are probably
attributable to Ctesibius. They demand no description here.
A hot-air engine, however, which is the subject of his 37th
proposition, is of real interest.
Hero sketches and describes a method of opening temple-doors by the
action of fire on an altar, which is an ingenious device, and contains
all the elements of the machine of the Marquis of Worcester, which is
generally considered the first real steam-engine, with the single and
vital defect that the expanding fluid is air instead of steam. The
sketch, from Greenwood's translation, exhibits the device very
plainly. Beneath the temple-doors, in the space _A B C D_, is placed a
spherical vessel, _H_, containing water. A pipe, _F G_, connects the
upper part of this sphere with the hollow and air-tight shell of the
altar above, _D E_. Another pipe, _K L M_, leads from the bottom of
the vessel, _H_, over, in syphon-shape, to the bottom of a suspended
bucket, _N X_. The suspending cord is carried over a pulley and led
around two vertical barrels, _O P_, turning on pivots at their feet,
and carrying the doors above. Ropes led over a pulley, _R_, sustain a
counterbalance, _W_.
[Illustration: FIG. 1.--Opening Temple-Doors by Steam, B. C. 200.]
On building a fire on the altar, the heated air within expands, passes
through the pipe, _F G_, and drives the water contained in the vessel,
_H_, through the syphon, _K L M_, into the bucket, _N X_. The weight
of the bucket, which then descends, turns the barrels, _O P_, raises
the counterbalance, and opens the doors of the temple. On
extinguishing the fire, the air is condensed, the water returns
through the syphon from the bucket to the sphere, the counterbalance
falls, and the doors are closed.
Another contrivance is next described, in which the bucket is replaced
by an air-tight bag, which, expanding as the heated air enters it,
contracts vertically and actuates the mechanism, which in other
respects is similar to that just described.
In these devices the spherical vessel is a perfect anticipation of
the vessels used many centuries later by several so-called inventors
of the steam-engine.
Proposition 45 describes the familiar experiment of a ball supported
aloft by a jet of fluid. In this example steam is generated in a close
cauldron, and issues from a pipe inserted in the top, the ball dancing
on the issuing jet.
No. 47 is a device subsequently reproduced--perhaps reinvented by the
second Marquis of Worcester.
[Illustration: FIG. 2.--Steam Fountain, B. C. 200.]
A strong, close vessel, _A B C D_, forms a pedestal, on which are
mounted a spherical vessel, _E F_, and a basin. A pipe, _H K_, is led
from the bottom of the larger vessel into the upper part of the
sphere, and another pipe from the lower part of the latter, in the
form of a syphon, over to the basin, _M_. A drain-pipe, _N O_, leads
from the basin to the reservoir, _A D_. The whole contrivance is
called "A fountain which is made to flow by the action of the sun's
rays."
It is operated thus: The vessel, _E F_, being filled nearly to the top
with water, or other liquid, and exposed to the action of the sun's
rays, the air above the water expands, and drives the liquid over,
through the syphon, _G_, into the basin, _M_, and it will fall into
the pedestal, _A B C D_.
Hero goes on to state that, on the removal of the sun's rays, the air
in the sphere will contract, and that the water will be returned to
the sphere from the pedestal. This can, evidently, only occur when the
pipe _G_ is closed previous to the commencement of this cooling. No
such cock is mentioned, and it is not unlikely that the device only
existed on paper.
Several steam-boilers are described, usually simple pipes or
cylindrical vessels, and the steam generated in them by the heat of
the fire on the altar forms a steam-blast. This blast is either
directed into the fire, or it "makes a blackbird sing," blows a horn
for a triton, or does other equally useless work. In one device, No.
70, the steam issues from a reaction-wheel revolving in the horizontal
plane, and causes dancing images to circle about the altar. A more
mechanical and more generally-known form of this device is that which
is frequently described as the "First Steam Engine." The sketch from
Stuart is similar in general form, but more elaborate in detail, than
that copied by Greenwood, which is here also reproduced, as
representing more accurately the simple form which the mechanism of
the "AEolipile," or Ball of AEolus, assumed in those early times.
[Illustration: FIG. 3.--Hero's Engine, B. C. 200.]
The cauldron, _A B_, contains water, and is covered by the steam-tight
cover, _C D_. A globe is supported above the cauldron by a pair of
tubes, terminating, the one, _C M_, in a pivot, _L_, and the other,
_E F_, opening directly into the sphere at _G_. Short, bent pipes, _H_
and _K_, issue from points diametrically opposite each other, and are
open at their extremities.
A fire being made beneath the cauldron, steam is formed and finds exit
through the pipe, _E F G_, into the globe, and thence rushes out of
the pipes, _H K_, turning the globe on its axis, _G L_, by the
unbalanced pressure thus produced.
The more elaborate sketch which forms the frontispiece represents a
machine of similar character. Its design and ornamentation illustrate
well the characteristics of ancient art, and the Greek idea of the
steam-engine.
This "AEolipile" consisted of a globe, _X_, suspended between
trunnions, _O S_, through one of which steam enters from the boiler,
_P_, below. The hollow, bent arms, _W_ and _Z_, cause the vapor to
issue in such directions that the reaction produces a rotary movement
of the globe, just as the rotation of reaction water-wheels is
produced by the outflowing water.
It is quite uncertain whether this machine was ever more than a toy,
although it has been supposed by some authorities that it was actually
used by the Greek priests for the purpose of producing motion of
apparatus in their temples.
It seems sufficiently remarkable that, while the power of steam had
been, during all the many centuries that man has existed upon the
globe, so universally displayed in so many of the phenomena of natural
change, that mankind lived almost up to the Christian era without
making it useful in giving motion even to a toy; but it excites still
greater surprise that, from the time of Hero, we meet with no good
evidence of its application to practical purposes for many hundreds of
years.
Here and there in the pages of history, and in special treatises, we
find a hint that the knowledge of the force of steam was not lost; but
it is not at all to the credit of biographers and of historians, that
they have devoted so little time to the task of seeking and recording
information relating to the progress of this and other important
inventions and improvements in the mechanic arts.
Malmesbury states[7] that, in the year A. D. 1125, there existed at
Rheims, in the church of that town, a clock designed or constructed by
Gerbert, a professor in the schools there, and an organ blown by air
escaping from a vessel in which it was compressed "by heated water."
[7] Stuart's "Anecdotes."
Hieronymus Cardan, a wonderful mathematical genius, a most eccentric
philosopher, and a distinguished physician, about the middle of the
sixteenth century called attention, in his writings, to the power of
steam, and to the facility with which a vacuum can be obtained by its
condensation. This Cardan was the author of "Cardan's Formula," or
rule for the solution of cubic equations, and was the inventor of the
"smoke-jack." He has been called a "philosopher, juggler, and madman."
He was certainly a learned mathematician, a skillful physician, and a
good mechanic.
Many traces are found, in the history of the sixteenth century, of the
existence of some knowledge of the properties of steam, and some
anticipation of the advantages to follow its application. Matthesius,
A. D. 1571, in one of his sermons describes a contrivance which may be
termed a steam-engine, and enlarges on the "tremendous results which
may follow the volcanic action of a small quantity of confined
vapor;"[8] and another writer applied the steam aeolipile of Hero to
turn the spit, and thus rivaled and excelled Cardan, who was
introducing his "smoke-jack."
[8] "Berg-Postilla, oder Sarepta von Bergwerk und Metallen."
Nuremberg, 1571.
As Stuart says, the inventor enumerated its excellent qualities with
great minuteness. He claimed that it would "eat nothing, and giving,
withal, an assurance to those partaking of the feast, whose
suspicious natures nurse queasy appetites, that the haunch has not
been pawed by the turnspit in the absence of the housewife's eye, for
the pleasure of licking his unclean fingers."[9]
[9] "History of the Steam-Engine," 1825.
Jacob Besson, a Professor of Mathematics and Natural Philosophy at
Orleans, and who was in his time distinguished as a mechanician, and
for his ingenuity in contriving illustrative models for use in his
lecture-room, left evidence, which Beroaldus collected and published
in 1578,[10] that he had found the spirit of his time sufficiently
enlightened to encourage him to pay great attention to applied
mechanics and to mechanism. There was at this time a marked awakening
of the more intelligent men of the age to the value of practical
mechanics. A scientific tract, published at Orleans in 1569, and
probably written by Besson, describes very intelligently the
generation of steam by the communication of heat to water, and its
peculiar properties.
[10] "Theatrum Instrumentorum et Machinarum, Jacobi Bessoni, cum
Franc Beroaldus, figuarum declaratione demonstrativa." Lugduni,
1578.
The French were now becoming more interested in mechanics and the
allied sciences, and philosophers and literati, of native birth and
imported by the court from other countries, were learning more of the
nature and importance of such studies as have a bearing upon the work
of the engineer and of the mechanic.
Agostino Ramelli, an Italian of good family, a student and an artist
when at leisure, a soldier and an engineer in busier times, was born
and educated at Rome, but subsequently was induced to make his home in
Paris. He published a book in 1588,[11] in which he described many
machines, adapted to various purposes, with a skill that was only
equaled by the accuracy and general excellence of his delineations.
This work was produced while its author was residing at the French
capital, supported by a pension which had been awarded him by Henry
III. as a reward for long and faithful services.
[11] "Le diverse et artificiose machine del Capitano Agostino
Ramelli, del Ponte della Prefia." Paris, 1588.
The books of Besson and of Ramelli are the first treatises of
importance on general machinery, and were, for many years, at once the
sources from which later writers drew the principal portion of their
information in relation to machinery, and wholesome stimulants to the
study of mechanism. These works contain descriptions of many machines
subsequently reinvented and claimed as new by other mechanics.
Leonardo da Vinci, well known as a mathematician, engineer, poet, and
painter, of the sixteenth century, describes, it is said, a steam-gun,
which he calls the "Architonnerre," and ascribes to Archimedes. It was
a machine composed of copper, and seems to have had considerable
power. It threw a ball weighing a talent. The steam was generated by
permitting water in a closed vessel to fall on surfaces heated by a
charcoal fire, and by its sudden expansion to eject the ball.
In the year 1825, the superintendent of the royal Spanish archives at
Simancas furnished an account which, it was said, had been there
discovered of an attempt, made in 1543 by Blasco de Garay, a Spanish
navy-officer under Charles V., to move a ship by paddle-wheels,
driven, as was inferred from the account, by a steam-engine.
It is impossible to say to how much credit the story is entitled, but,
if true, it was the first attempt, so far as is now known, to make
steam useful in developing power for practical purposes. Nothing is
known of the form of the engine employed, it only having been stated
that a "vessel of boiling water" formed a part of the apparatus.
The account is, however, in other respects so circumstantial, that it
has been credited by many; but it is regarded as apocryphal by the
majority of writers upon the subject. It was published in 1826 by M.
de Navarrete, in Zach's "Astronomical Correspondence," in the form of
a letter from Thomas Gonzales, Director of the Royal Archives at
Simancas, Spain.
In 1601, Giovanni Battista della Porta, in a work called "Spiritali,"
described an apparatus by which the pressure of steam might be made to
raise a column of water. It included the application of the
condensation of steam to the production of a vacuum into which the
water would flow.
Porta is described as a mathematician, chemist, and physicist, a
gentleman of fortune, and an enthusiastic student of science. His home
in Naples was a rendezvous for students, artists, and men of science
distinguished in every branch. He invented the magic lantern and the
camera obscura, and described it in his commentary on the
"Pneumatica." In his work,[12] he described this machine for raising
water, as shown in Fig. 4, which differs from one shown by Hero in the
use of steam pressure, instead of the pressure of heated air, for
expelling the liquid.
[12] "Pneumaticorum libri tres," etc., 4to. Naples, 1601. "I Tre
Libri de' Spiritali." Napoli, 1606.
The retort, or boiler, is fitted to a tank from which the bent pipe
leads into the external air. A fire being kindled under the retort,
the steam generated rises to the upper part of the tank, and its
pressure on the surface of the water drives it out through the pipe,
and it is then led to any desired height. This was called by Porta an
improved "Hero's Fountain," and was named his "Steam Fountain." He
described with perfect accuracy the action of condensation in
producing a vacuum, and sketched an apparatus in which the vacuum thus
secured was filled by water forced in by the pressure of the external
atmosphere. His contrivances were not apparently ever applied to any
practically useful purpose. We have not yet passed out of the age of
speculation, and are just approaching the period of application. Porta
is, nevertheless, entitled to credit as having proposed an essential
change in this succession, which begins with Hero, and which did not
end with Watt.
[Illustration: FIG. 4.--Porta's Apparatus, A. D. 1601.]
The use of steam in Hero's fountain was as necessary a step as,
although less striking than, any of the subsequent modifications of
the machine. In Porta's contrivance, too, we should note particularly
the separation of the boiler from the "forcing vessel"--a plan often
claimed as original with later inventors, and as constituting a fair
ground for special distinction.
The rude engraving (Fig. 4) above is copied from the book of Porta,
and shows plainly the boiler mounted above a furnace, from the door of
which the flame is seen issuing, and above is the tank containing
water. The opening in the top is closed by the plug, as shown, and the
steam issuing from the boiler into the tank near the top, the water
is driven out through the pipe at the left, leading up from the bottom
of the tank.
[Illustration: FIG. 5.--De Caus's Apparatus, A. D. 1605.]
Florence Rivault, a Gentleman of the Bedchamber to Henry IV., and a
teacher of Louis XIII., is stated by M. Arago, the French philosopher,
to have discovered, as early as 1605, that water confined in a
bomb-shell and there heated would explode the shell, however thick its
walls might be made. The fact was published in Rivault's treatise on
artillery in 1608. He says: "The water is converted into air, and its
vaporization is followed by violent explosion."
In 1615, Salomon de Caus, who had been an engineer and architect under
Louis XIII. of France, and later in the employ of the English Prince
of Wales, published a work at Frankfort, entitled "Les Raisons des
Forces Mouvantes, avec diverses machines tant utile que plaisante," in
which he illustrated his proposition, "Water will, by the aid of fire,
mount higher than its source," by describing a machine designed to
raise water by the expanding power of steam.
In the sketch here given (Fig. 5), and which is copied from the
original in "Les Raisons des Forces Mouvantes," etc., _A_ is the
copper ball containing water; _B_, the cock at the extremity of the
pipe, taking water from the bottom, _C_, of the vessel; _D_, the cock
through which the vessel is filled. The sketch was probably made by De
Caus's own hand.
The machine of De Caus, like that of Porta, thus consisted of a metal
vessel partly filled with water, and in which a pipe was fitted,
leading nearly to the bottom, and open at the top. Fire being applied,
the steam formed by its elastic force drove the water out through the
vertical pipe, raising it to a height limited only by either the
desire of the builder or the strength of the vessel.
In 1629, Giovanni Branca, of the Italian town of Loretto, described,
in a work[13] published at Rome, a number of ingenious mechanical
contrivances, among which was a steam-engine (Fig. 6), in which the
steam, issuing from a boiler, impinged upon the vanes of a horizontal
wheel. This it was proposed to apply to many useful purposes.
[13] "Le Machine deverse del Signior Giovanni Branca, cittadino
Romano, Ingegniero, Architetto della Sta. Casa di Loretto." Roma,
MDCXXIX.
At this time experiments were in progress in England which soon
resulted in the useful application of steam-power to raising water.
[Illustration: FIG. 6.--Branca's Steam-Engine, A. D. 1629.]
A patent, dated January 21, 1630, was granted to David Ramseye[14] by
Charles I., which covered a number of distinct inventions. These were:
"1. To multiply and make saltpeter in any open field, in fower acres
of ground, sufficient to serve all our dominions. 2. To raise water
from low pitts by fire. 3. To make any sort of mills to goe on
standing waters by continual motion, without help of wind, water, or
horse. 4. To make all sortes of tapistrie without any weaving-loom, or
waie ever yet in use in this kingdome. 5. To make boats, shippes, and
barges to goe against strong wind and tide. 6. To make the earth more
fertile than usual. 7. To raise water from low places and mynes, and
coal pitts, by a new waie never yet in use. 8. To make hard iron soft,
and likewise copper to be tuffe and soft, which is not in use in this
kingdome. 9. To make yellow waxe white verie speedilie."
[14] Rymer's "F[oe]dera," Sanderson. Ewbank's "Hydraulics," p. 419.
This seems to have been the first authentic reference to the use of
steam in the arts which has been found in English literature. The
patentee held his grant fourteen years, on condition of paying an
annual fee of L3 6_s._ 8_d._ to the Crown.
The second claim is distinct as an application of steam, the language
being that which was then, and for a century and a half subsequently,
always employed in speaking of its use. The steam-engine, in all its
forms, was at that time known as the "fire-engine." It would seem not
at all improbable that the third, fifth, and seventh claims are also
applications of steam-power.
Thomas Grant, in 1632, and Edward Ford, in 1640, also patented
schemes, which have not been described in detail, for moving ships
against wind and tide by some new and great force.
Dr. John Wilkins, Bishop of Chester, an eccentric but learned and
acute scholar, described, in 1648, Cardan's smoke-jack, the earlier
aeolipiles, and the power of the confined steam, and suggested, in a
humorous discourse, what he thought to be perfectly feasible--the
construction of a flying-machine. He says: "Might not a 'high
pressure' be applied with advantage to move wings as large as those of
the 'ruck's' or the 'chariot'? The engineer might probably find a
corner that would do for a coal-station near some of the 'castles'"
(castles in the air). The reverend wit proposed the application of the
smoke-jack to the chiming of bells, the reeling of yarn, and to
rocking the cradle.
Bishop Wilkins writes, in 1648 ("Mathematical Magic"), of aeolipiles as
familiar and useful pieces of apparatus, and describes them as
consisting "of some such material as may endure the fire, having a
small hole at which they are filled with water, and out of which (when
the vessels are heated) the air doth issue forth with a strong and
lasting violence." "They are," the bishop adds, "frequently used for
the exciting and contracting of heat in the melting of glasses or
metals. They may also be contrived to be serviceable for sundry other
pleasant uses, as for the moving of sails in a chimney-corner, the
motion of which sails may be applied to the turning of a spit, or the
like."
Kircher gives an engraving ("Mundus Subterraneus") showing the
last-named application of the aeolipile; and Erckern ("Aula
Subterranea," 1672) gives a picture illustrating their application to
the production of a blast in smelting ores. They seem to have been
frequently used, and in all parts of Europe, during the seventeenth
century, for blowing fires in houses, as well as in the practical work
of the various trades, and for improving the draft of chimneys. The
latter application is revived very frequently by the modern inventor.
SECTION II.--THE PERIOD OF APPLICATION--WORCESTER, PAPIN, AND SAVERY.
We next meet with the first instance in which the expansive force of
steam is supposed to have actually been applied to do important and
useful work.
In 1663, Edward Somerset, second Marquis of Worcester, published a
curious collection of descriptions of his inventions, couched in
obscure and singular language, and called "A Century of the Names and
Scantlings of Inventions by me already Practised."
One of these inventions is an apparatus for raising water by steam.
The description was not accompanied by a drawing, but the sketch here
given (Fig. 7) is thought probably to resemble one of his earlier
contrivances very closely.
Steam is generated in the boiler _a_, and thence is led into the
vessel _e_, already nearly filled with water, and fitted up like the
apparatus of De Caus. It drives the water in a jet out through the
pipe _f_. The vessel _e_ is then shut off from the boiler _a_, is
again filled through the pipe _h_, and the operation is repeated.
Stuart thinks it possible that the marquis may have even made an
engine with a piston, and sketches it.[15] The instruments of Porta
and of De Caus were "steam fountains," and were probably applied, if
used at all, merely to ornamental purposes. That of the Marquis of
Worcester was actually used for the purpose of elevating water for
practical purposes at Vauxhall, near London.
[15] "Anecdotes of the Steam-Engine," vol. i., p. 61.
[Illustration: Edward Somerset, the Second Marquis of Worcester.]
How early this invention was introduced at Raglan Castle by Worcester
is not known, but it was probably not much later than 1628. In 1647
Dircks shows the marquis probably to have been engaged in getting out
parts of the later engine which was erected at Vauxhall, obtaining
his materials from William Lambert, a brass-founder. His patent was
issued in June, 1663.
[Illustration: FIG. 7.--Worcester's Steam Fountain, A. D. 1650.]
We nowhere find an illustrated description of the machine, or such an
account as would enable a mechanic to reproduce it in all its details.
Fortunately, the cells and grooves (Fig. 9) remaining in the wall of
the citadel of Raglan Castle indicate the general dimensions and
arrangement of the engine; and Dircks, the biographer of the inventor,
has suggested the form of apparatus shown in the sketch (Fig. 8) as
most perfectly in accord with the evidence there found, and with the
written specifications.
The two vessels, _A A'_, are connected by a steam-pipe, _B B'_, with
the boiler, _C_, behind them. _D_ is the furnace. A vertical
water-pipe, _E_, is connected with the cold-water vessels, _A A'_, by
the pipes, _F F'_, reaching nearly to the bottom. Water is supplied by
the pipes, _G G'_, with valves, _a a'_, dipping into the well or
ditch, _H_. Steam from the boiler being admitted to each vessel, _A_
and _A'_, alternately, and there condensing, the vacuum formed permits
the pressure of the atmosphere to force the water from the well
through the pipes, _G_ and _G'_. While one is filling, the steam is
forcing the charge of water from the other up the discharge-pipe, _E_.
As soon as each is emptied, the steam is shut off from it and turned
into the other, and the condensation of the steam remaining in the
vessel permits it to fill again. As will be seen presently, this is
substantially, and almost precisely, the form of engine of which the
invention is usually attributed to Savery, a later inventor.
[Illustration: FIG. 8.--Worcester's Engine, A. D. 1665.]
[Illustration: FIG. 9.--Wall of Raglan Castle.]
Worcester never succeeded in forming the great company which he hoped
would introduce his invention on a scale commensurate with its
importance, and his fate was that of nearly all inventors. He died
poor and unsuccessful.
His widow, who lived until 1681, seemed to have become as confident as
was Worcester himself that the invention had value, and, long after
his death, was still endeavoring to secure its introduction, but with
equal non-success. The steam-engine had taken a form which made it
inconceivably valuable to the world, at a time when no more efficient
means of raising water was available at the most valuable mines than
horse-power; but the people, greatly as it was needed, were not yet
sufficiently intelligent to avail themselves of the great boon, the
acceptance of which was urged upon them with all the persistence and
earnestness which characterizes every true inventor.
Worcester is described by his biographer as having been a learned,
thoughtful, studious, and good man--a Romanist without prejudice or
bigotry, a loyal subject, free from partisan intolerance; as a public
man, upright, honorable, and humane; as a scholar, learned without
being pedantic; as a mechanic, patient, skillful, persevering, and of
wonderful ingenuity, and of clear, almost intuitive, apprehension.
Yet, with all these natural advantages, reinforced as they were by
immense wealth and influence in his earlier life, and by hardly
lessened social and political influence when a large fortune had been
spent in experiment, and after misfortune had subdued his spirits and
left him without money or a home, the inventor failed to secure the
introduction of a device which was needed more than any other.
Worcester had attained practical success; but the period of
speculation was but just closing, and that of the application of steam
had not quite yet arrived.
The second Marquis of Worcester stands on the record as the first
steam-engine builder, and his death marks the termination of the first
of those periods into which we have divided the history of the growth
of the steam-engine.
The "water-commanding engine," as its inventor called it, was the
first instance in the history of the steam-engine in which the
inventor is known to have "reduced his invention to practice."
It is evident, however, that the invention of the separate boiler,
important as it was, had been anticipated by Porta, and does not
entitle the marquis to the honor, claimed for him by many English
authorities, of being _the_ inventor of the steam-engine. Somerset was
simply _one_ of those whose works collectively made the steam-engine.
After the time of Worcester, we enter upon a stage of history which
may properly be termed a period of application; and from this time
forward steam continued to play a more and more important part in
social economy, and its influence on the welfare of mankind augmented
with a rapidly-increasing growth.
The knowledge then existing of the immense expansive force of steam,
and the belief that it was destined to submit to the control of man
and to lend its immense power in every department of industry, were
evidently not confined to any one nation. From Italy to Northern
Germany, and from France to Great Britain, the distances, measured in
time, were vastly greater then than now, when this wonderful genius
has helped us to reduce weeks to hours; but there existed,
notwithstanding, a very perfect system of communication, and the
learning of every centre was promptly radiated to every other. It thus
happened that, at this time, the speculative study of the steam-engine
was confined to no part of Europe; inventors and experimenters were
busy everywhere developing this promising scheme.
Jean Hautefeuille, the son of a French _boulanger_, born at Orleans,
adopted by the Duchess of Bouillon at the suggestion of De Sourdis,
profiting by the great opportunities offered him, entered the Church,
and became one of the most learned men and greatest mechanicians of
his time. He studied the many schemes then brought forward by
inventors with the greatest interest, and was himself prolific of new
ideas.
In 1678, he proposed the use of alcohol in an engine, "in such a
manner that the liquid should evaporate and be condensed, _tour a
tour_, without being wasted"[16]--the first recorded plan, probably,
for surface-condensation and complete retention of the working-fluid.
He proposed a gunpowder-engine, of which[17] he described three
varieties.
[16] Stuart's "Anecdotes."
[17] "Pendule Perpetuelle, avec la maniere d'elever d'eau par le
moyen de la poudre a canon," Paris, 1678.
In one of these engines he displaced the atmosphere by the gases
produced by the explosion, and the vacuum thus obtained was utilized
in raising water by the pressure of the air. In the second machine,
the pressure of the gases evolved by the combustion of the powder
acted directly upon the water, forcing it upward; and in the third
design, the pressure of the vapor drove a piston, and this engine was
described as fitted to supply power for many purposes. There is no
evidence that he constructed these machines, however, and they are
here referred to simply as indicating that all the elements of the
machine were becoming well known, and that an ingenious mechanic,
combining known devices, could at this time have produced the
steam-engine. Its early appearance should evidently have been
anticipated.
Hautefeuille, if we may judge from evidence at hand, was the first to
propose the use of a piston in a heat-engine, and his gunpowder-engine
seems to have been the first machine which would be called a
heat-engine by the modern mechanic. The earlier "machines" or
"engines," including that of Hero and those of the Marquis of
Worcester, would rather be denominated "apparatus," as that term is
used by the physicist or the chemist, than a machine or an engine, as
the terms are used by the engineer.
Huyghens, in 1680, in a memoir presented to the Academy of Sciences,
speaks of the expansive force of gunpowder as capable of utilization
as a convenient and portable mechanical power, and indicates that he
had designed a machine in which it could be applied.
This machine of Huyghens is of great interest, not simply because it
was the first gas-engine and the prototype of the very successful
modern explosive gas-engine of Otto and Langen, but principally as
having been the first engine which consisted of a cylinder and piston.
The sketch shows its form. It consisted of a cylinder, _A_, a piston,
_B_, two relief-pipes, _C C_, fitted with check-valves and a system of
pulleys, _F_, by which the weight is raised. The explosion of the
powder at _H_ expels the air from the cylinder. When the products of
combustion have cooled, the pressure of the atmosphere is no longer
counterbalanced by that of air beneath, and the piston is forced down,
raising the weight. The plan was never put in practice, although the
invention was capable of being made a working and possibly useful
machine.
[Illustration: FIG. 10.--Huyghens's Engine, 1680.]
At about this period the English attained some superiority over their
neighbors on the Continent in the practical application of science and
the development of the useful arts, and it has never since been lost.
A sudden and great development of applied science and of the useful
arts took place during the reign of Charles II., which is probably
largely attributable to the interest taken by that monarch in many
branches of construction and of science. He is said to have been very
fond of mathematics, mechanics, chemistry, and natural history, and to
have had a laboratory erected, and to have employed learned men to
carry on experiments and lines of research for his satisfaction. He
was especially fond of the study and investigation of the arts and
sciences most closely related to naval architecture and navigation,
and devoted much attention to the determination of the best forms of
vessels, and to the discovery of the best kinds of ship-timber. His
brother, the Duke of York, was equally fond of this study, and was his
companion in some of his work.
Great as is the influence of the monarch, to-day, in forming the
tastes and habits and in determining the direction of the studies and
labors of the people, his influence was vastly more potent in those
earlier days; and it may well be believed that the rapid strides taken
by Great Britain from that time were, in great degree, a consequence
of the well-known habits of Charles II., and that the nation, which
had an exceptional natural aptitude for mechanical pursuits, should
have been prompted by the example of its king to enter upon such a
course as resulted in the early attainment of an advanced position in
all branches of applied science.
The appointment, under Sir Robert Moray, the superintendent of the
laboratory of the king, of Master Mechanic, was conferred upon Sir
Samuel Morland, a nobleman who, in his practical knowledge of
mechanics and in his ingenuity and fruitfulness of invention, was
apparently almost equal to Worcester. He was the son of a Berkshire
clergyman, was educated at Cambridge, where he studied mathematics
with great interest, and entered public life soon after. He served the
Parliament under Cromwell, and afterward went to Geneva. He was of a
decidedly literary turn of mind, and wrote a history of the Piedmont
churches, which gave him great repute with the Protestant party. He
was induced subsequently, on the accession of Charles II., to take
service under that monarch, whose gratitude he had earned by revealing
a plot for his assassination.
He received his appointment and a baronetcy in 1660, and immediately
commenced making experiments, partly at his own expense and partly at
the cost of the royal exchequer, which were usually not at all
remunerative. He built hand fire-engines of various kinds, taking
patents on them, which brought him as small profits as did his work
for the king, and invented the speaking-trumpet, calculating machines,
and a capstan. His house at Vauxhall was full of curious devices, the
products of his own ingenuity.
He devoted much attention to apparatus for raising water. His devices
seem to have usually been modifications of the now familiar
force-pump. They attracted much attention, and exhibitions were made
of them before the king and queen and the court. He was sent to France
on business relating to water-works erected for King Charles, and
while in Paris he constructed pumps and pumping apparatus for the
satisfaction of Louis XIV. In his book,[18] published in Paris in
1683, and presented to the king, and an earlier manuscript,[19] still
preserved in the British Museum, Morland shows a perfect familiarity
with the power of steam. He says, in the latter: "Water being
evaporated by fire, the vapors require a greater space (about two
thousand times) than that occupied by the water; and, rather than
submit to imprisonment, it will burst a piece of ordnance. But, being
controlled according to the laws of statics, and, by science, reduced
to the measure of weight and balance, it bears its burden peaceably
(like good horses), and thus may be of great use to mankind,
especially for the raising of water, according to the following table,
which indicates the number of pounds which may be raised six inches,
1,800 times an hour, by cylinders half-filled with water, and of the
several diameters and depths of said cylinders."
[18] "Elevation des Eaux par toute sorte de Machines reduite a la
Mesure au Poids et a la Balance, presentee a Sa Majeste Tres
Chretienne, par le Chevalier Morland, Gentilhomme Ordinaire de la
Chambre Privee et Maistre de Mechaniques du Roy de la Grande
Bretagne, 1683."
[19] "Les Principes de la Nouvelle Force de Feu, inventee par le
Chevalier Morland, l'an 1682, et presentee a Sa Majeste Tres
Chretienne, 1683."
He then gives the following table, a comparison of which with modern
tables proves Morland to have acquired a very considerable and
tolerably accurate knowledge of the volume and pressure of saturated
steam:
-------------------------+------------------------
CYLINDERS. | POUNDS.
-----------+-------------+----------------------
Diameter | Depth | Weight
in Feet. | in Feet. | to be Raised.
-----------+-------------+----------------------
1 | 2 | 15
2 | 4 | 120
3 | 6 | 405
4 | 8 | 960
5 | 10 | 1,876
6 | 10 | 3,240
-----------+-------------+----------------------
Number of cylinders having a diameter of 6 feet
and a depth of 12 feet.
| |
1 | 12 | 3,240
2 | 12 | 6,480
3 | 12 | 9,720
4 | 12 | 12,960
5 | 12 | 16,200
6 | 12 | 19,440
7 | 12 | 22,680
8 | 12 | 25,920
9 | 12 | 29,190
10 | 12 | 32,400
20 | 12 | 64,800
30 | 12 | 97,200
40 | 12 | 129,600
50 | 12 | 162,000
60 | 12 | 194,400
70 | 12 | 226,800
80 | 12 | 259,200
90 | 12 | 291,600
-----------+-------------+----------------------
The rate of enlargement of volume in the conversion of water into
steam, as given in Morland's book, appears remarkably accurate when
compared with statements made by other early experimenters.
Desaguliers gave the ratio of volumes at 14,000, and this was accepted
as correct for many years, and until Watt's experiments, which were
quoted by Dr. Robison as giving the ratio at between 1,800 and 1,900.
Morland also states the "duty" of his engines in the same manner in
which it is stated by engineers to-day.
Morland must undoubtedly have been acquainted with the work of his
distinguished contemporary, Lord Worcester, and his apparatus seems
most likely to have been a modification--perhaps improvement--of
Worcester's engine. His house was at Vauxhall, and the establishment
set up for the king was in the neighborhood. It may be that Morland is
to be credited with greater success in the introduction of his
predecessor's apparatus than the inventor himself.
Dr. Hutton considered this book to have been the earliest account of
the steam-engine, and accepts the date--1682--as that of the
invention, and adds, that "the project seems to have remained obscure
in both countries till 1699, when Savery, who probably knew more of
Morland's invention than he owned, obtained a patent," etc. We have,
however, scarcely more complete or accurate knowledge of the extent of
Morland's work, and of its real value, than of that of Worcester.
Morland died in 1696, at Hammersmith, not far from London, and his
body lies in Fulham church.
From this time forward the minds of many mechanicians were earnestly
at work on this problem--the raising of water by aid of steam.
Hitherto, although many ingenious toys, embodying the principles of
the steam-engine separately, and sometimes to a certain extent
collectively, had been proposed, and even occasionally constructed,
the world was only just ready to profit by the labors of inventors in
this direction.
But, at the end of the seventeenth century, English miners were
beginning to find the greatest difficulty in clearing their shafts of
the vast quantities of water which they were meeting at the
considerable depths to which they had penetrated, and it had become a
matter of vital importance to them to find a more powerful aid in that
work than was then available. They were, therefore, by their
necessities stimulated to watch for, and to be prepared promptly to
take advantage of, such an invention when it should be offered them.
The experiments of Papin, and the practical application of known
principles by Savery, placed the needed apparatus in their hands.
[Illustration: Thomas Savery.]
THOMAS SAVERY was a member of a well-known family of Devonshire,
England, and was born at Shilston, about 1650. He was well educated,
and became a military engineer. He exhibited great fondness for
mechanics, and for mathematics and natural philosophy, and gave much
time to experimenting, to the contriving of various kinds of
apparatus, and to invention. He constructed a clock, which still
remains in the family, and is considered an ingenious piece of
mechanism, and is said to be of excellent workmanship.
He invented and patented an arrangement of paddle-wheels, driven by a
capstan[20] for propelling vessels in calm weather, and spent some
time endeavoring to secure its adoption by the British Admiralty and
the Navy Board, but met with no success. The principal objector was
the Surveyor of the Navy, who dismissed Savery, with a remark which
illustrates a spirit which, although not yet extinct, is less
frequently met with in the public service now than then: "What have
interloping people, that have no concern with us, to do to pretend to
contrive or invent things for us?"[21] Savery then fitted his
apparatus into a small vessel, and exhibited its operation on the
Thames. The invention was never introduced into the navy, however.
[20] Harris, "Lexicon Technicum," London, 1710.
[21] "Navigation Improved; or, The Art of Rowing Ships of all rates
in Calms, with a more Easy, Swift, and Steady Motion, than Oars
can," etc., etc. By Thomas Savery, Gent. London, 1698.
It was after this time that Savery became the inventor of a
steam-engine. It is not known whether he was familiar with the work of
Worcester, and of earlier inventors. Desaguliers[22] states that he
had read the book of Worcester, and that he subsequently endeavored to
destroy all evidence of the anticipation of his own invention by the
marquis by buying up all copies of the century that he could find, and
burning them. The story is scarcely credible. A comparison of the
drawings given of the two engines exhibits, nevertheless, a striking
resemblance; and, assuming that of the marquis's engine to be correct,
Savery is to be given credit for the finally successful introduction
of the "semi-omnipotent" "water-commanding" engine of Worcester.
[22] "Experimental Philosophy," vol. ii., p. 465.
The most important advance in actual construction, therefore, was made
by Thomas Savery. The constant and embarrassing expense, and the
engineering difficulties presented by the necessity of keeping the
British mines, and particularly the deep pits of Cornwall, free from
water, and the failure of every attempt previously made to provide
effective and economical pumping-machinery, were noted by Savery, who,
July 25, 1698, patented the design of the first engine which was ever
actually employed in this work. A working-model was submitted to the
Royal Society of London in 1699, and successful experiments were made
with it. Savery spent a considerable time in planning his engine and
in perfecting it, and states that he expended large sums of money upon
it.
Having finally succeeded in satisfying himself with its operation, he
exhibited a model "Fire-Engine," as it was called in those days,
before King William III. and his court, at Hampton Court, in 1698, and
obtained his patent without delay. The title of the patent reads: "A
grant to Thomas Savery, Gentl., of the sole exercise of a new
invention by him invented, for raising of water, and occasioning
motion to all sorts of mill-works, by the impellant force of fire,
which will be of great use for draining mines, serving towns with
water, and for the working of all sorts of mills, when they have not
the benefit of water nor constant winds; to hold for 14 years; with
usual clauses."
Savery now went about the work of introducing his invention in a way
which is in marked contrast with that usually adopted by the inventors
of that time. He commenced a systematic and successful system of
advertisement, and lost no opportunity of making his plans not merely
known, but well understood, even in matters of detail. The Royal
Society was then fully organized, and at one of its meetings he
obtained permission to appear with his model "fire-engine" and to
explain its operation; and, as the minutes read, "Mr. Savery
entertained the Society with showing his engine to raise water by the
force of fire. He was thanked for showing the experiment, which
succeeded, according to expectation, and was approved of." He
presented to the Society a drawing and specifications of his machine,
and "The Transactions"[23] contain a copperplate engraving and the
description of his model. It consisted of a furnace, _A_, heating a
boiler, _B_, which was connected by pipes, _C C_, with two copper
receivers, _D D_. There were led from the bottom of these receivers
branch pipes, _F F_, which turned upward, and were united to form a
rising main, or "forcing-pipe," _G_. From the top of each receiver was
led a pipe, which was turned downward, and these pipes united to form
a suction-pipe, which was led down to the bottom of the well or
reservoir from which the water was to be drawn. The maximum lift
allowable was stated at 24 feet.
[23] "Philosophical Transactions, No. 252." Weld's "Royal Society,"
vol. i., p. 357. Lowthorp's "Abridgment," vol. i.
[Illustration: FIG. 11.--Savery's Model, 1698.]
The engine was worked as follows: Steam is raised in the boiler, _B_,
and a cock, _C_, being opened, a receiver, _D_, is filled with steam.
Closing the cock, _C_, the steam condensing in the receiver, a vacuum
is created, and the pressure of the atmosphere forces the water up,
through the supply-pipe, from the well into the receiver. Opening the
cock, _C_, again, the check-valve in the suction-pipe at _E_ closes,
the steam drives the water out through the forcing-pipe, _G_, the
clack-valve, _E_, on that pipe opening before it, and the liquid is
expelled from the top of the pipe. The valve, _C_, is again closed;
the steam again condenses, and the engine is worked as before. While
one of the two receivers is discharging, the other is filling, as in
the machine of the Marquis of Worcester, and thus the steam is drawn
from the boiler with tolerable regularity, and the expulsion of water
takes place with similar uniformity, the two systems of receivers and
pipes being worked alternately by the single boiler.
In another and still simpler little machine,[24] which he erected at
Kensington (Fig. 12), the same general plan was adopted, combining a
suction-pipe, _A_, 16 feet long and 3 inches in diameter; a single
receiver, _B_, capable of containing 13 gallons; a boiler, _C_, of
about 40 gallons capacity; a forcing-pipe, _D_, 42 feet high, with the
connecting pipe and cocks, _E F G_; and the method of operation was as
already described, except that _surface-condensation_ was employed,
the cock, _F_, being arranged to shower water from the rising main
over the receiver, as shown. Of the first engine Switzer says: "I have
heard him say myself, that the very first time he played, it was in a
potter's house at Lambeth, where, though it was a small engine, yet it
(the water) forced its way through the roof, and struck off the tiles
in a manner that surprised all the spectators."
[24] Bradley, "New Improvements of Planting and Gardening." Switzer,
"Hydrostatics," 1729.
[Illustration: FIG. 12.--Savery's Engine, 1698.]
The Kensington engine cost L50, and raised 3,000 gallons per hour,
filling the receiver four times a minute, and required a bushel of
coal per day. Switzer remarks: "It must be noted that this engine is
but a small one in comparison with many others that are made for
coal-works; but this is sufficient for any reasonable family, and
other uses required of it in watering all middling gardens." He
cautions the operator: "When you have raised water enough, and you
design to leave off working the engine, take away all the fire from
under the boiler, and open the cock (connected to the funnel) to let
out the steam, which would otherwise, were it to remain confined,
perhaps burst the engine."
With the intention of making his invention more generally known, and
hoping to introduce it as a pumping-engine in the mining districts of
Cornwall, Savery wrote a prospectus for general circulation, which
contains the earliest account of the later and more effective form of
engine. He entitled his pamphlet "The Miner's Friend; or, A
Description of an Engine to raise Water by Fire described, and the
Manner of fixing it in Mines, with an Account of the several Uses it
is applicable to, and an Answer to the Objections against it." It was
printed in London in 1702, for S. Crouch, and was distributed among
the proprietors and managers of mines, who were then finding the flow
of water at depths so great as, in some cases, to bar further
progress. In many cases, the cost of drainage left no satisfactory
margin of profit. In one mine, 500 horses were employed raising water,
by the then usual method of using horse-gins and buckets.
The approval of the King and of the Royal Society, and the countenance
of the mine-adventurers of England, were acknowledged by the author,
who addressed his pamphlet to them.
The engraving of the engine was reproduced, with the description, in
Harris's "Lexicon Technicum," 1704; in Switzer's "Hydrostatics," 1729;
and in Desaguliers's "Experimental Philosophy," 1744.
The sketch which here follows is a neater engraving of the same
machine. Savery's engine is shown in Fig. 13, as described by Savery
himself, in 1702, in "The Miner's Friend."
_L_ is the boiler in which steam is raised, and through the pipes _O
O_ it is alternately let into the vessels _P P_.
[Illustration: FIG. 13.--Savery's Engine, A. D. 1702.]
Suppose it to pass into the left-hand vessel first. The valve _M_
being closed, and _R_ being opened, the water contained in _P_ is
driven out and up the pipe _S_ to the desired height, where it is
discharged.
The valve _R_ is then closed, and the valve in the pipe _O_; the valve
_M_ is next opened, and condensing water is turned upon the exterior
of _P_ by the cock _Y_, leading water from the cistern _X_. As the
steam contained in _P_ is condensed, forming a vacuum there, a fresh
charge of water is driven by atmospheric pressure up the pipe _T_.
Meantime, steam from the boiler has been let into the right-hand
vessel _P_, the cock _W_ having been first closed, and _R_ opened.
The charge of water is driven out through the lower pipe and the cock
_R_, and up the pipe _S_ as before, while the other vessel is
refilling preparatory to acting in its turn.
The two vessels are thus alternately charged and discharged, as long
as is necessary.
Savery's method of supplying his boiler with water was at once simple
and ingenious.
The small boiler, _D_, is filled with water from any convenient
source, as from the stand-pipe, _S_. A fire is then built under it,
and, when the pressure of steam in _D_ becomes greater than in the
main boiler, _L_, a communication is opened between their lower ends,
and the water passes, under pressure, from the smaller to the larger
boiler, which is thus "fed" without interrupting the work. _G_ and _N_
are _gauge-cocks_, by which the height of water in the boilers is
determined; they were first adopted by Savery.
Here we find, therefore, the first really practicable and commercially
valuable steam-engine. Thomas Savery is entitled to the credit of
having been the first to introduce a machine in which the power of
heat, acting through the medium of steam, was rendered generally
useful.
It will be noticed that Savery, like the Marquis of Worcester, used a
boiler separate from the water-reservoir.
He added to the "water-commanding engine" of the marquis the system of
_surface-condensation_, by which he was enabled to charge his vessels
when it became necessary to refill them; and added, also, the
secondary boiler, which enabled him to supply the working-boiler with
water without interrupting its work.
The machine was thus made capable of working uninterruptedly for a
period of time only limited by its own decay.
Savery never fitted his boilers with safety-valves, although it was
done earlier by Papin; and in deep mines he was compelled to make use
of higher pressures than his rudely-constructed boilers could safely
bear.
Savery's engine was used at a number of mines, and also for supplying
water to towns; some large estates, country houses, and other private
establishments, employed them for the same purpose. They did not,
however, come into general use among the mines, because, according to
Desaguliers, they were apprehensive of danger from the explosion of
the boilers or receivers. As Desaguliers wrote subsequently: "Savery
made a great many experiments to bring this machine to perfection, and
did erect several which raised water very well for gentlemen's seats,
but could not succeed for mines, or supplying towns, where the water
was to be raised very high and in great quantities; for then the steam
required being boiled up to such a strength as to be ready to tear all
the vessels to pieces." "I have known Captain Savery, at York's
buildings, to make steam eight or ten times stronger than common air;
and then its heat was so great that it would melt common soft solder,
and its strength so great as to blow open several joints of the
machine; so that he was forced to be at the pains and charge to have
all his joints soldered with spelter or hard solder."
Although there were other difficulties in the application of the
Savery engine to many kinds of work, this was the most serious one,
and explosions did occur with fatal results. The writer just quoted
relates, in his "Experimental Philosophy," that a man who was ignorant
of the nature of the engine undertook to work a machine which
Desaguliers had provided with a safety-valve to avoid this very
danger, "and, having hung the weight at the further end of the
steelyard, in order to collect more steam in order to make his work
the quicker, he hung also a very heavy plumber's iron upon the end of
the steelyard; the consequence proved fatal; for, after some time, the
steam, not being able, with the safety-cock, to raise up the steelyard
loaded with all this unusual weight, burst the boiler with a great
explosion, and killed the poor man." This is probably the earliest
record of a steam-boiler explosion.
Savery proposed to use his engine for driving mills; but there is no
evidence that he actually made such an application of the machine,
although it was afterward so applied by others. The engine was not
well adapted to the drainage of surface-land, as the elevation of
large quantities of water through small heights required great
capacity of receivers, or compelled the use of several engines for
each case. The filling of the receivers, in such cases, also compelled
the heating of large areas of cold and wet metallic surfaces by the
steam at each operation, and thus made the work comparatively wasteful
of fuel. Where used in mines, they were necessarily placed within 30
feet or less of the lowest level, and were therefore exposed to danger
of submergence whenever, by any accident, the water should rise above
that level. In many cases this would result in the loss of the engine,
and the mine would remain "drowned," unless another engine should be
procured to pump it out. Where the mine was deep, the water was forced
by the pressure of steam from the level of the engine-station to the
top of the lift. This compelled the use of pressures of several
atmospheres in many cases; and a pressure of three atmospheres, or
about 45 pounds per square inch, was considered, in those days, as
about the maximum pressure allowable. This difficulty was met by
setting a separate engine at every 60 or 80 feet, and pumping the
water from one to the other. If any one engine in the set became
disabled, the pumping was interrupted until that one machine could be
repaired. The size of Savery's largest boilers was not great, their
maximum diameter not exceeding two and a half feet. This made it
necessary to provide several of his engines, usually, for a single
mine, and at each level. The first cost and the expense of repairs
were exceedingly serious items. The expense and danger, either real or
apparent, were thus sufficient to deter many from their use, and the
old method of raising water by horse-power was adhered to.
The consumption of fuel with these engines was very great. The steam
was not generated economically, as the boilers used were of such
simple forms as only could then be produced, and presented too little
heating surface to secure a very complete transfer of heat from the
gases of combustion to the water within the boiler. This waste in the
generation of steam in these uneconomical boilers was followed by
still more serious waste in its application, without expansion, to the
expulsion of water from a metallic receiver, the cold and wet sides of
which absorbed heat with the greatest avidity. The great mass of the
liquid was not, however, heated by the steam, and was expelled at the
temperature at which it was raised from below.
Savery quaintly relates the action of his machine in "The Miner's
Friend," and so exactly, that a better description could scarcely be
asked: "The steam acts upon the surface of the water in the receiver,
which surface only being heated by the steam, it does not condense,
but the steam gravitates or presses with an elastic quality like air,
and still increasing its elasticity or spring, until it counterpoises,
or rather exceeds, the weight of the column of water in the
force-pipe, which then it will necessarily drive up that pipe; the
steam then takes some time to recover its power, but it will at last
discharge the water out at the top of the pipe. You may see on the
outside of the receiver how the water goes out, as well as if it were
transparent; for, so far as the steam is contained within the vessel,
it is dry without, and so hot as scarcely to endure the least touch of
the hand; but so far as the water is inside the vessel, it will be
cold and wet on the outside, where any water has fallen on it; which
cold and moisture vanish as fast as the steam takes the place of the
water in its descent."
After Savery's death, in 1716, several of these engines were erected
in which some improvements were introduced. Dr. Desaguliers, in 1718,
built a Savery engine, in which he avoided some defects which he, with
Dr. Gravesande, had noted two years earlier. They had then proposed
to adopt the arrangement of a single receiver which had been used by
Savery himself, as already described, finding, by experiment on a
model which they had made for the purpose, that one could be
discharged three times, while the same boiler would empty two
receivers but once each. In their arrangement, the steam was shut back
in the boiler while the receiver was filling with water, and a high
pressure thus accumulated, instead of being turned into the second
receiver, and the pressure thus kept comparatively low.
[Illustration: FIG. 14.--Papin's Two-Way Cock.]
In the engine built in 1718, Desaguliers used a spherical boiler,
which he provided with the lever safety-valve already applied by
Papin, and adopted a comparatively small receiver--one-fifth the
capacity of the boiler--of slender cylindrical form, and attached a
pipe leading the water for condensation into the vessel, and effected
its distribution by means of the "rose," or a "sprinkling-plate," such
as is still frequently used in modern engines having jet-condensers.
This substitution of jet for surface-condensation was of very great
advantage, securing great promptness in the formation of a vacuum and
a rapid filling of the receiver. A "two-way cock" admitted steam to
the receiver, or, being turned the other way, admitted the cold
condensing water. The dispersion of the water in minute streams or
drops was a very important detail, not only as securing great
rapidity of condensation, but enabling the designer to employ a
comparatively small receiver or condenser.
The engine is shown in Fig. 15, which is copied from the "Experimental
Philosophy" of Desaguliers.
[Illustration: FIG. 15.--Engine built by Desaguliers in 1718.]
The receiver, _A_, is connected to the boiler, _B_, by a steam-pipe,
_C_, terminating at the two-way cock, _D_; the "forcing-pipe," _E_,
has at its foot a check-valve, _F_, and the valve _G_ is a similar
check at the head of the suction-pipe. _H_ is a strainer, to prevent
the ingress of chips or other bodies carried to the pipe by the
current; the cap above the valves is secured by a bridle, or stirrup,
and screw, _I_, and may be readily removed to clear the valves or to
renew them; _K_ is the handle of the two-way cock; _M_ is the
injection-cock, and is kept open during the working of the engine; _L_
is the chimney-flue; _N_ and _O_ are gauge-cocks fitted to pipes
leading to the proper depths within the boiler, the water-line being
somewhere between the levels of their lower ends; _P_ is a lever
safety-valve, as first used on the "Digester" of Papin; _R_ is the
reservoir into which the water is pumped; _T_ is the flue, leading
spirally about the boiler from the furnace, _V_, to the chimney; _Y_
is a cock fitted in a pipe through which the rising-main may be filled
from the reservoir, should injection-water be needed when that pipe is
empty.
Seven of these engines were built, the first of which was made for the
Czar of Russia. Its boiler had a capacity of "five or six hogsheads,"
and the receiver, "holding one hogshead," was filled and emptied four
times a minute. The water was raised "by suction" 29 feet, and forced
by steam pressure 11 feet higher.
Another engine built at about this time, to raise water 29 feet "by
suction," and to force it 24 feet higher, made 6 "strokes" per minute,
and, when forcing water but 6 or 8 feet, made 8 or 9 strokes per
minute. Twenty-five years later a workman overloaded the safety-valve
of this engine, by placing the weight at the end and then adding "a
very heavy plumber's iron." The boiler exploded, killing the
attendant.
Desaguliers says that one of these engines, capable of raising ten
tons an hour 38 feet, in 1728 or 1729, cost L80, exclusive of the
piping.
Blakely, in 1766, patented an improved Savery engine, in which he
endeavored to avoid the serious loss due to condensation of the steam
by direct contact with the water, by interposing a cushion of oil,
which floated upon the water and prevented the contact of the steam
with the surface of the water beneath it. He also used air for the
same purpose, sometimes in double receivers, one supported on the
other. These plans did not, however, prove satisfactory.
Rigley, of Manchester, England, soon after erected Savery engines, and
applied them to the driving of mills, by pumping water into
reservoirs, from whence it returned to the wells or ponds from which
it had been raised, turning water-wheels as it descended.
Such an arrangement was in operation many years at the works of a Mr.
Kiers, St. Pancras, London. It is described in detail, and
illustrated, in Nicholson's "Philosophical Journal," vol. i., p. 419.
It had a "wagon-boiler" 7 feet long, 5 wide, and 5 deep; the wheel was
18 feet in diameter, and drove the lathes and other machinery of the
works. In this engine Blakely's plan of injecting air was adopted. The
injection-valve was a clack, which closed automatically when the
vacuum was formed.
The engine consumed 6 or 7 bushels of good coals, and made 10 strokes
per minute, raising 70 cubic feet of water 14 feet, and developing
nearly 3 horse-power.
Many years after Savery's death, in 1774, Smeaton made the first
duty-trials of engines of this kind. He found that an engine having a
cylindrical receiver 16 inches in diameter and 22 feet high,
discharging the water raised 14 feet above the surface of the water in
the well, making 12 strokes, and raising 100 cubic feet per minute,
developed 2-2/3 horse-power, and consumed 3 hundredweight of coals in
four hours. Its duty was, therefore, 5,250,000 pounds raised one foot
per bushel of 84 pounds of coals, or 62,500 "foot-pounds" of work per
pound of fuel. An engine of slightly greater size gave a duty about 5
per cent. greater.
When Louis XIV. revoked the edict of Nantes, by which Henry IV. had
guaranteed protection to the Protestants of France, the terrible
persecutions at once commenced drove from the kingdom some of its
greatest men. Among these was Denys Papin.
It was at about this time that the influence of the atmospheric
pressure on the boiling-point began to be observed, Dr. Hooke having
found that the boiling-point was a fixed temperature under the
ordinary pressure of the atmosphere, and the increase in temperature
and pressure of steam when confined having been shown by Papin with
his "Digester."
Denys Papin was of a family which had attached itself to the
Protestant Church; but he was given his education in the school of the
Jesuits at Blois, and there acquired his knowledge of mathematics. His
medical education was given him at Paris, although he probably
received his degree at Orleans. He settled in Paris in 1672, with the
intention of practising his profession, and devoted all his spare
time, apparently, to the study of physics.
[Illustration: Denys Papin.]
Meantime, that distinguished philosopher, Huyghens, the inventor of
the clock and of the gunpowder-engine, had been induced by the
linen-draper's apprentice, Colbert, now the most trusted adviser of
the king, to take up his residence in Paris, and had been made one of
the earliest members of the Academy of Science, which was founded at
about that time. Papin became an assistant to Huyghens, and aided him
in his experiments in mechanics, having been introduced by Madame
Colbert, who was also a native of Blois. Here he devised several
modifications of the instruments of Guericke, and printed a
description of them.[25] This little book was presented to the
Academy, and very favorably noticed. Papin now became well known among
contemporary men of science at Paris, and was well received
everywhere. Soon after, in the year 1675, as stated by the _Journal
des Savants_, he left Paris and took up his residence in England,
where he very soon made the acquaintance of Robert Boyle, the founder,
and of the members of the Royal Society. Boyle speaks of Papin as
having gone to England in the hope of finding a place in which he
could satisfactorily pursue his favorite studies.
[25] "Nouvelles Experiences du Vuide, avec la description des
Machines qui servent a le faire." Paris, 1674.
Boyle himself had already been long engaged in the study of
pneumatics, and had been especially interested in the investigations
which had been original with Guericke. He admitted young Papin into
his laboratory, and the two philosophers worked together at these
attractive problems. It was while working with Boyle that Papin
invented the double air-pump and the air-gun.
Papin and his work had now become so well known, and he had attained
so high a position in science, that he was nominated for membership in
the Royal Academy, and was elected December 16, 1680. He at once took
his place among the most talented and distinguished of the great men
of his time.
He probably invented his "Digester" while in England, and it was first
described in a brochure written in English, under the title, "The New
Digester." It was subsequently published in Paris.[26] This was a
vessel, _B_ (Fig. 16), capable of being tightly closed by a screw,
_D_, and a lid, _C_, in which food could be cooked in water raised by
a furnace, _A_, to the temperature due to any desired safe pressure of
steam. The pressure was determined and limited by a weight, _W_, on
the safety-valve lever, _G_. It is probable that this essential
attachment to the steam-boiler had previously been used for other
purposes; but Papin is given the credit of having first made use of it
to control the pressure of steam.
[26] "La maniere d'amollir les os et de faire cuire toutes sortes de
viandes," etc.
[Illustration: FIG. 16.--Papin's Digester, 1680.]
From England, Papin went to Italy, where he accepted membership and
held official position in the Italian Academy of Science. Papin
remained in Venice two years, and then returned to England. Here, in
1687, he announced one of his inventions, which is just becoming of
great value in the arts. He proposed to transmit power from one point
to another, over long distances, by the now well-known "pneumatic"
method. At the point where power was available, he exhausted a
chamber by means of an air-pump, and, leading a pipe to the distant
point at which it was to be utilized, there withdrew the air from
behind a piston, and the pressure of the air upon the latter caused it
to recede into the cylinder, in which it was fitted, raising a weight,
of which the magnitude was proportionate to the size of the piston and
the degree of exhaustion. Papin was not satisfactorily successful in
his experiments; but he had created the germ of the modern system of
pneumatic transmission of power. His disappointment at the result of
his efforts to utilize the system was very great, and he became
despondent, and anxious to change his location again.
In 1687 he was offered the chair of Mathematics at Marburg by Charles,
the Landgrave of Upper Hesse, and, accepting the appointment, went to
Germany. He remained in Germany many years, and continued his
researches with renewed activity and interest. His papers were
published in the "Acta Eruditorum" at Leipsic, and in the
"Philosophical Transactions" at London. It was while at Marburg that
his papers descriptive of his method of pneumatic transmission of
power were printed.[27]
[27] "Recueil des diverses Pieces touchant quelques Nouvelles
Machines et autres Sujets Philosophiques," M. D. Papin. Cassel,
1695.
In the "Acta Eruditorum" of 1688 he exhibited a practicable plan, in
which he exhausted the air from a set of engines or pumps by means of
pumps situated at a long distance from the point of application of the
power, and at the place where the prime mover--which was in this case
a water-wheel--was erected.
After his arrival at the University of Marburg, Papin exhibited
to his colleagues in the faculty a modification of Huyghens's
gunpowder-engine, in which he had endeavored to obtain a more perfect
vacuum than had Huyghens in the first of these machines. Disappointed
in this, he finally adopted the expedient of employing steam to
displace the air, and to produce, by its condensation, the perfect
vacuum which he sought; and he thus produced _the first steam-engine
with a piston_, and the first piston steam-engine, in which
condensation was produced to secure a vacuum. It was described in the
"Acta" of Leipsic,[28] in June, 1690, under the title, "Nova Methodus
ad vires motrices validissimas leri pretio comparandeo" ("A New Method
of securing cheaply Motive Power of considerable Magnitude"). He
describes first the gunpowder-engine, and continues by stating that,
"until now, all experiments have been unsuccessful; and after the
combustion of the exploded powder, there always remains in the
cylinder about one-fifth its volume of air." He says that he has
endeavored to arrive by another route at the same end; and "as, by a
natural property of water, a small quantity of this liquid, vaporized
by the action of heat, acquires an elasticity like that of the air,
and returns to the liquid state again on cooling, without retaining
the least trace of its elastic force," he thought that it would be
easy to construct machines in which, "by means of a moderate heat, and
without much expense," a more perfect vacuum could be produced than
could be secured by the use of gunpowder.
[28] "Acta Eruditorum," Leipsic, 1690.
[Illustration: FIG. 17.--Papin's Engine.]
The first machine of Papin (Fig. 17) was very similar to the
gunpowder-engine already described as the invention of Huyghens. In
place of gunpowder, a small quantity of water is placed at the bottom
of the cylinder, _A_; a fire is built beneath it, "the bottom being
made of very thin metal," and the steam formed soon raises the piston,
_B_, to the top, where a latch, _E_, engaging a notch in the
piston-rod, _H_, holds it up until it is desired that it shall drop.
The fire being removed, the steam condenses, and a vacuum is formed
below the piston, and the latch, _E_, being disengaged, the piston is
driven down by the superincumbent atmosphere and raises the weight
which has been, meantime, attached to a rope, _L_, passing from the
piston-rod over pulleys, _T T_. The machine had a cylinder two and a
half inches in diameter, and raised 60 pounds once a minute; and Papin
calculated that a machine of a little more than two feet diameter of
cylinder and of four feet stroke would raise 8,000 pounds four feet
per minute--i. e., that it would yield about one horse-power.
The inventor claimed that this new machine would be found useful in
relieving mines from water, in throwing bombs, in ship-propulsion,
attaching revolving paddles--i. e., paddle-wheels--to the sides of the
vessel, which wheels were to be driven by several of his engines, in
order to secure continuous motion, the piston-rods being fitted with
racks which were to engage ratchet-wheels on the paddle-shafts.
"The principal difficulty," he says, answering anticipated objections,
"is that of making these large cylinders."
In a reprint describing his invention, in 1695, Papin gives a
description of a "newly-invented furnace," a kind of fire-box
steam-boiler, in which the fire, completely surrounded by water, makes
steam so rapidly that his engine could be driven at the rate of four
strokes per minute by the steam supplied by it.
Papin also proposed the use of a peculiar form of furnace with this
engine, which, embodying as it does some suggestions that very
probably have since been attributed to later inventors, deserves
special notice. In this furnace, Papin proposed to burn his fuel on a
grate within a furnace arranged with a _down-draught_, the air
entering above the grate, passing _down_ through the fire, and from
the ash-pit through a side flue to the chimney. In starting the fire,
the coal was laid on the grate, covered with wood, and the latter was
ignited, the flame, passing downward through the coal, igniting that
in turn, and, as claimed by Papin, the combustion was complete, and
the formation of smoke was entirely prevented. He states, in "Acta
Eruditorum," that the heat was intense, the saving of fuel very great,
and that the only difficulty was to find a refractory material which
would withstand the high temperature attained.
This is the first fire-box and flue boiler of which we have record.
The experiment is supposed to have led Papin to suggest the use of a
hot-blast, as practised by Neilson more than a century later, for
reducing metals from their ores.
Papin made another boiler having a flue winding through the
water-space, and presenting a heating surface of nearly 80 square
feet. The flue had a length of 24 feet, and was about 10 inches
square. It is not stated what were the maximum pressures carried on
these boilers; but it is known that Papin had used very high pressures
in his digesters--probably between 1,200 and 1,500 pounds per square
inch.
In the year 1705, Leibnitz, then visiting England, had seen a Savery
engine, and, on his return, described it to Papin, sending him a
sketch of the machine. Papin read the letter and exhibited the sketch
to the Landgrave of Hesse, and Charles at once urged him to endeavor
to perfect his own machine, and to continue the researches which he
had been intermittently pursuing since the earlier machine had been
exhibited in public.
In a small pamphlet printed at Cassel in 1707,[29] Papin describes a
new form of engine, in which he discards the original plan of a
modified Huyghens engine, with tight-fitting piston and cylinder,
raising its load by indirect action, and makes a modified Savery
engine, which he calls the "Elector's Engine," in honor of his patron.
This is the engine shown in the engraving, and as proposed to be used
by him in turning a water-wheel.
[29] "Nouvelle maniere d'elever l'Eau par la Force du Feu, mis en
Lumiere," par D. Papin. Cassel, 1707.
The sketch is that given by the inventor in his memoir. It consists
(Fig. 18) of a steam-boiler, _a_, from which steam is led through the
cock, _c_, to the working cylinder, _n n_. The water beneath the
floating-piston, _h_, which latter serves simply as a cushion to
protect the steam from sudden condensation or contact with the water,
is forced into the vessel _r r_, which is a large air-chamber, and
which serves to render the outflow of water comparatively uniform, and
the discharge occurs by means of the pipe _q_, from which the water
rises to the desired height. A fresh supply of water is introduced
through the funnel _k_, after condensation of the steam in _n n_, and
the operation of expulsion is repeated.
[Illustration: FIG. 18.--Papin's Engine and Water-Wheel, A. D. 1707.]
This machine is evidently a retrogression, and Papin, after having
earned the honor of having invented the first steam-engine of the
typical form which has since become so universally applied, forfeited
that credit by his evident ignorance of its superiority over existing
devices, and by attempting unsuccessfully to perfect the inferior
device of another inventor.
Subsequently, Papin made an attempt to apply the steam-engine to the
propulsion of vessels, the account of which will be given in the
chapter on Steam-Navigation.
Again disappointed, Papin once more visited England, to renew his
acquaintance with the _savans_ of the Royal Society; but Boyle had
died during the period which Papin had spent in Germany, and the
unhappy and disheartened inventor and philosopher died in 1810,
without having seen any one of his many devices and ingenious
inventions a practical success.
[Illustration]
CHAPTER II.
_THE STEAM-ENGINE AS A TRAIN OF MECHANISM._
"The introduction of new Inventions seemeth to be the very chief of
all human Actions. The Benefits of new Inventions may extend to all
Mankind universally; but the Good of political Achievements can
respect but some particular Cantons of Men; these latter do not
endure above a few Ages, the former forever. Inventions make all Men
happy, without either Injury or Damage to any one single Person.
Furthermore, new Inventions are, as it were, new Erections and
Imitations of God's own Works."--BACON.
THE MODERN TYPE, AS DEVELOPED BY NEWCOMEN, BEIGHTON, AND SMEATON.
At the beginning of the eighteenth century every element of the modern
type of steam-engine had been separately invented and practically
applied. The character of atmospheric pressure, and of the pressure of
gases, had become understood. The nature of a vacuum was known, and
the method of obtaining it by the displacement of the air by steam,
and by the condensation of the vapor, was understood. The importance
of utilizing the power of steam, and the application of condensation
in the removal of atmospheric pressure, was not only recognized, but
had been actually and successfully attempted by Morland, Papin, and
Savery.
Mechanicians had succeeded in making steam-boilers capable of
sustaining any desired or any useful pressure, and Papin had shown how
to make them comparatively safe by the attachment of the
safety-valve. They had made steam-cylinders fitted with pistons, and
had used such a combination in the development of power.
It now only remained for the engineer to combine known forms of
mechanism in a practical machine which should be capable of
economically and conveniently utilizing the power of steam through the
application of now well-understood principles, and by the intelligent
combination of physical phenomena already familiar to scientific
investigators.
Every essential fact and every vital principle had been learned, and
every one of the needed mechanical combinations had been successfully
effected. It was only requisite that an inventor should appear,
capable of perceiving that these known facts and combinations of
mechanism, properly illustrated in a working machine, would present to
the world its greatest physical blessing.
The defects of the simple engines constructed up to this time have
been noted as each has been described. None of them could be depended
upon for safe, economical, and continuous work. Savery's was the most
successful of all. But the engine of Savery, even with the
improvements of Desaguliers, was unsafe where most needed, because of
the high pressures necessarily carried in its boilers when pumping
from considerable depths; it was uneconomical, in consequence of the
great loss of heat in its forcing-cylinders when the hot steam was
surrounded at its entrance by colder bodies; it was slow in operation,
of great first cost, and expensive in first cost and in repairs, as
well as in its operation. It could not be relied upon to do its work
uninterruptedly, and was thus in many respects a very unsatisfactory
machine.
The man who finally effected a combination of the elements of the
modern steam-engine, and produced a machine which is unmistakably a
true engine--i. e., a train of mechanism consisting of several
elementary pieces combined in a train capable of transmitting a force
applied at one end and of communicating it to the resistance to be
overcome at the other end--was THOMAS NEWCOMEN, an "iron-monger" and
blacksmith of Dartmouth, England. The engine invented by him, and
known as the "Atmospheric Steam-Engine," is the first of an entirely
new type.
The old type of engine--the steam-engine as a simple machine--had been
given as great a degree of perfection, by the successive improvements
of Worcester, Savery, and Desaguliers, as it was probably capable of
attaining by any modification of its details. The next step was
necessarily a complete change of type; and to effect such a change, it
was only necessary to combine devices already known and successfully
tried.
But little is known of the personal history of Newcomen. His position
in life was humble, and the inventor was not then looked upon as an
individual of even possible importance in the community. He was
considered as one of an eccentric class of schemers, and of an order
which, concerning itself with mechanical matters, held the lowest
position in the class.
It is supposed that Savery's engine was perfectly well known to
Newcomen, and that the latter may have visited Savery at his home in
Modbury, which was but fifteen miles from the residence of Newcomen.
It is thought, by some biographers of these inventors, that Newcomen
was employed by Savery in making the more intricate forgings of his
engine. Harris, in his "Lexicon Technicum," states that drawings of
the engine of Savery came into the hands of Newcomen, who made a model
of the machine, set it up in his garden, and then attempted its
improvement; but Switzer says that Newcomen "was as early in his
invention as Mr. Savery was in his."
Newcomen was assisted in his experiments by John Calley, who, with
him, took out the patent. It has been stated that a visit to Cornwall,
where they witnessed the working of a Savery engine, first turned
their attention to the subject; but a friend of Savery has stated
that Newcomen was as early with his general plans as Savery.
After some discussion with Calley, Newcomen entered into
correspondence with Dr. Hooke, proposing a steam-engine to consist of
a _steam-cylinder containing a piston similar to that of Papin's, and
to drive a separate pump_, similar to those generally in use where
water was raised by horse or wind power. Dr. Hooke advised and argued
strongly against their plan, but, fortunately, the obstinate belief of
the unlearned mechanics was not overpowered by the disquisitions of
their distinguished correspondent, and Newcomen and Calley attempted
an engine on their peculiar plan. This succeeded so well as to induce
them to continue their labors, and, in 1705, to patent,[30] in
combination with Savery--who held the exclusive right to practise
surface-condensation, and who induced them to allow him an interest
with them--an engine combining a steam-cylinder and piston,
surface-condensation, a separate boiler, and separate pumps.
[30] It has been denied that a patent was issued, but there is no
doubt that Savery claimed and received an interest in the new
engine.
In the atmospheric-engine, as first designed, the slow process of
condensation by the application of the condensing water to the
exterior of the cylinder, to produce the vacuum, caused the strokes of
the engine to take place at very long intervals. An improvement was,
however, soon effected, which immensely increased the rapidity of
condensation. A jet of water was thrown directly _into_ the cylinder,
thus effecting for the Newcomen engine just what Desaguliers had done
for the Savery engine previously. As thus improved, the Newcomen
engine is shown in Fig. 19.
Here _b_ is the boiler. Steam passes from it through the cock, _d_,
and up into the cylinder, _a_, equilibrating the pressure of the
atmosphere, and allowing the heavy pump-rod, _k_, to fall, and, by
the greater weight acting through the beam, _i i_, to raise the
piston, _s_, to the position shown. The rod _m_ carries a
counterbalance, if needed. The cock _d_ being shut, _f_ is then
opened, and a jet of water from the reservoir, _g_, enters the
cylinder, producing a vacuum by the condensation of the steam. The
pressure of the air above the piston now forces it down, again raising
the pump-rods, and thus the engine works on indefinitely.
[Illustration: FIG. 19.--Newcomen's Engine, A. D. 1705.]
The pipe _h_ is used for the purpose of keeping the upper side of the
piston covered with water, to prevent air-leaks--a device of Newcomen.
Two gauge-cocks, _c c_, and a safety-valve, _N_, are represented in
the figure, but it will be noticed that the latter is quite different
from the now usual form. Here, the pressure used was hardly greater
than that of the atmosphere, and the weight of the valve itself was
ordinarily sufficient to keep it down. The condensing water, together
with the water of condensation, flows off through the open pipe _p_.
Newcomen's first engine made 6 or 8 strokes a minute; the later and
improved engines made 10 or 12.
The steam-engine has now assumed a form that somewhat resembles the
modern machine.
The Newcomen engine is seen at a glance to have been a combination of
earlier ideas. It was the engine of Huyghens, with its cylinder and
piston as improved by Papin, by the substitution of steam for the
gases generated by the explosion of gunpowder; still further improved
by Newcomen and Calley by the addition of the method of condensation
used in the Savery engine. It was further modified, with the object of
applying it directly to the working of the pumps of the mines by the
introduction of the overhead beam, from which the piston was suspended
at one end and the pump-rod at the other.
The advantages secured by this combination of inventions were many and
manifest. The piston not only gave economy by interposing itself
between the impelling and the resisting fluid, but, by affording
opportunity to make the area of piston as large as desired, it enabled
Newcomen to use any convenient pressure and any desired proportions
for any proposed lift. The removal of the water to be lifted from the
steam-engine proper and handling it with pumps, was an evident cause
of very great economy of steam.
The disposal of the water to be raised in this way also permitted the
operations of condensation of steam, and the renewal of pressure on
the piston, to be made to succeed each other with rapidity, and
enabled the inventor to choose, unhampered, the device for securing
promptly the action of condensation.
Desaguliers, in his account of the introduction of the engine of
Newcomen, says that, with his coadjutor Calley, he "made several
experiments in private about the year 1710, and in the latter end of
the year 1711 made proposals to drain the water of a colliery at
Griff, in Warwickshire, where the proprietors employed 500 horses, at
an expense of L900 a year; but, their invention not meeting with the
reception they expected, in March following, through the acquaintance
of Mr. Potter, of Bromsgrove, in Worcestershire, they bargained to
draw water for Mr. Back, of Wolverhampton, where, after a great many
laborious attempts, they did make the engine work; but, not being
either philosophers to understand the reason, or mathematicians enough
to calculate the powers and proportions of the parts, they very
luckily, by accident, found what they sought for.
"They were at a loss about the pumps, but, being so near Birmingham,
and having the assistance of so many admirable and ingenious workmen,
they came, about 1712, to the method of making the pump-valves,
clacks, and buckets, whereas they had but an imperfect notion of them
before. One thing is very remarkable: as they were at first working,
they were surprised to see the engine go several strokes, and very
quick together, when, after a search, they found a hole in the piston,
which let the cold water in to condense the steam in the inside of the
cylinder, whereas, before, they had always done it on the outside.
They used before to work with a buoy to the cylinder, inclosed in a
pipe, which buoy rose when the steam was strong and opened the
injection, and made a stroke; thereby they were only capable of giving
6, 8, or 10 strokes in a minute, till a boy, named Humphrey Potter, in
1713, who attended the engine, added (what he called a _scoggan_) a
catch, that the beam always opened, and then it would go 15 or 16
strokes a minute. But, this being perplexed with catches and strings,
Mr. Henry Beighton, in an engine he had built at Newcastle-upon-Tyne
in 1718, took them all away but the beam itself, and supplied them in
a much better manner."
In illustration of the application of the Newcomen engine to the
drainage of mines, Farey describes a small machine, of which the pump
is 8 inches in diameter, and the lift 162 feet. The column of water
to be raised weighed 3,535 pounds. The steam-piston was made 2
feet in diameter, giving an area of 452 square inches. The net
working-pressure was assumed at 10-3/4 pounds per square inch; the
temperature of the water of condensation and of uncondensed vapor
after the entrance of the injection-water being usually about 150 deg.
Fahr. This gave an excess of pressure on the steam-side of 1,324
pounds, the total pressure on the piston being 4,859 pounds. One-half
of this excess is counterweighted by the pump-rods, and by weight on
that end of the beam; and the weight, 662 pounds, acting on each side
alternately as a surplus, produced the requisite rapidity of movement
of the machine. This engine was said to make 15 strokes per minute,
giving a speed of piston of 75 feet per minute, and the power exerted
usefully was equivalent to 265,125 pounds raised one foot high per
minute. As the horse-power is equivalent to 33,000 "foot-pounds" per
minute, the engine was of 265125/33000 = 8.034--almost exactly 8
horse-power.
It is instructive to contrast this estimate with that made for a
Savery engine doing the same work. The latter would have raised the
water about 26 feet in its "suction-pipe," and would then have forced
it, by the direct pressure of steam, the remaining distance of 136
feet; and the steam-pressure required would have been nearly 60 pounds
per square inch. With this high temperature and pressure, the waste of
steam by condensation in the forcing-vessels would have been so great
that it would have compelled the adoption of two engines of
considerable size, each lifting the water one-half the height, and
using steam of about 25 pounds pressure. Potter's rude valve-gear was
soon improved by Henry Beighton, in an engine which that talented
engineer erected at Newcastle-upon-Tyne in 1718, and in which he
substituted substantial materials for the cords, as in Fig. 20.
In this sketch, _r_ is a plug-tree, plug-rod, or plug-frame, as it is
variously called, suspended from the great beam, with which it rises
and falls, bringing the pins _p_ and _k_, at the proper moment, in
contact with the handles _k k_ and _n n_ of the valves, moving them in
the proper direction and to the proper extent. A lever safety-valve is
here used, at the suggestion, it is said, of Desaguliers. The piston
was packed with leather or with rope, and lubricated with tallow.
[Illustration: FIG. 20.--Beighton's Valve-Gear, A. D. 1718.]
After the death of Beighton, the atmospheric engine of Newcomen
retained its then standard form for many years, and came into
extensive use in all the mining districts, particularly in Cornwall,
and was also applied occasionally to the drainage of wet lands, to the
supply of water to towns, and it was even proposed by Hulls to be used
for ship-propulsion.
The proportions of the engines had been determined in a hap-hazard
way, and they were in many cases very unsafe. John Smeaton, the most
distinguished engineer of his time, finally, in 1769, experimentally
determined proper proportions, and built several of these engines of
very considerable size. He built his engines with steam-cylinders of
greater length of stroke than had been customary, and gave them such
dimensions as, by giving a greater excess of pressure on the
steam-side, enabled him to obtain a greatly-increased speed of piston.
The first of his new style of engine was erected at Long Benton, near
Newcastle-upon-Tyne, in 1774.
Fig. 21[31] illustrates its principal characteristic features. The
boiler is not shown.
[31] A fac-simile of a sketch in Galloway's "On the Steam-Engine,"
etc.
The steam is led to the engine through the pipe, _C_, and is regulated
by turning the cock in the receiver, _D_, which connects with the
steam-cylinder by the pipe, _E_, which latter pipe rises a little way
above the bottom of the cylinder, _F_, in order that it may not drain
off the injection-water into the steam-pipe and receiver.
The steam-cylinder, about ten feet in length, is fitted with a
carefully-made piston, _G_, having a flanch rising four or five inches
and extending completely around its circumference, and nearly in
contact with the interior surface of the cylinder. Between this flanch
and the cylinder is driven a "packing" of oakum, which is held in
place by weights; this prevents the leakage of air, water, or steam,
past the piston, as it rises and falls in the cylinder at each stroke
of the engine. The chain and piston-rod connect the piston to the
beam, _I I_. The arch-heads at each end of the beam keep the chains of
the piston-rod and the pump-rods perpendicular and in line.
[Illustration: FIG. 21.--Smeaton's Newcomen Engine.]
A "jack-head" pump, _N_, is driven by a small beam deriving its motion
from the plug-rod at _g_, raises the water required for condensing
the steam, and keeps the cistern, _O_, supplied. This "jack-head
cistern" is sufficiently elevated to give the water entering the
cylinder the velocity requisite to secure prompt condensation. A
waste-pipe carries away any surplus water. The injection-water is led
from the cistern by the pipe, _P P_, which is two or three inches in
diameter, and the flow of water is regulated by the injection-cock,
_r_. The cap at the end, _d_, is pierced with several holes, and the
stream thus divided rises in jets when admitted, and, striking the
lower side of the piston, the spray thus produced very rapidly
condenses the steam, and produces a vacuum beneath the piston. The
valve, _e_, on the upper end of the injection-pipe, is a check-valve,
to prevent leakage into the engine when the latter is not in
operation. The little pipe, _f_, supplies water to the upper side of
the piston, and, keeping it flooded, prevents the entrance of air when
the packing is not perfectly tight.
The "working-plug," or plug-rod, _Q_, is a piece of timber slit
vertically, and carrying pins which engage the handles of the valves,
opening and closing them at the proper times. The steam-cock, or
regulator, has a handle, _h_, by which it is moved. The iron rod, _i
i_, or spanner, gives motion to the handle, _h_.
The vibrating lever, _k l_, called the _Y_, or the "tumbling-bob,"
moves on the pins, _m n_, and is worked by the levers, _o p_, which in
turn are moved by the plug-tree. When _o_ is depressed, the loaded
end, _k_, is given the position seen in the sketch, and the leg _l_ of
the _Y_ strikes the spanner, _i i_, and, opening the steam-valve, the
piston at once rises as steam enters the cylinder, until another pin
on the plug-rod raises the piece, _P_, and closes the regulator again.
The lever, _q r_, connects with the injection-cock, and is moved,
when, as the piston rises, the end, _q_, is struck by a pin on the
plug-rod, and the cock is opened and a vacuum produced. The cock is
closed on the descent of the plug-tree with the piston. An
eduction-pipe, _R_, fitted with a clock, conveys away the water in the
cylinder at the end of each down-stroke; the water thus removed is
collected in the hot-well, _S_, and is used as feed-water for the
boiler, to which it is conveyed by the pipe _T_. At each down-stroke,
while the water passes out through _R_, the air which may have
collected in the cylinder is driven out through the "snifting-valve,"
_s_. The steam-cylinder is supported on strong beams, _t t_; it has
around its upper edge a guard, _v_, of lead, which prevents the
overflow of the water on the top of the piston. The excess of this
water flows away to the hot-well through the pipe _W_.
Catch-pins, _x_, are provided, to prevent the beam descending too far
should the engine make too long a stroke; two wooden springs, _y y_,
receive the blow. The great beam is carried on sectors, _z z_, to
diminish losses by friction.
The boilers of Newcomen's earlier engines were made of copper where in
contact with the products of combustion, and their upper parts were of
lead. Subsequently, sheet-iron was substituted. The steam-space in the
boiler was made of 8 or 10 times the capacity of the cylinder of the
engine. Even in Smeaton's time, a chimney-damper was not used, and the
supply of steam was consequently very variable. In the earlier
engines, the cylinder was placed on the boiler; afterward, they were
placed separately, and supported on a foundation of masonry. The
injection or "jack-head" cistern was placed from 12 to 30 feet above
the engine, the velocity due the greater altitude being found to give
the most perfect distribution of the water and the promptest
condensation.
[Illustration: FIG. 22.--Boiler of Newcomen's Engine, 1768.]
Smeaton covered the lower side of his steam-pistons with wooden plank
about 2-1/4 inches thick, in order that it should absorb and waste
less heat than when the iron was directly exposed to the steam. Mr.
Beighton was the first to use the water of condensation for feeding
the boiler, taking it directly from the eduction-pipe, or the
"hot-well." Where only a sufficient amount of pure water could be
obtained for feeding the boiler, and the injection-water was "hard,"
Mr. Smeaton applied a heater, immersed in the hot-well, through which
the feed passed, absorbing heat from the water of condensation _en
route_ to the boiler. Farey first proposed the use of the
"coil-heater"--a pipe, or "worm," which, forming a part of the
feed-pipe, was set in the hot-well.
As early as 1743, the metal used for the cylinders was cast-iron. The
earlier engines had been fitted with brass cylinders. Desaguliers
recommended the iron cylinders, as being smoother, thinner, and as
having less capacity for heat than those of brass.
In a very few years after the invention of Newcomen's engine it had
been introduced into nearly all large mines in Great Britain; and many
new mines, which could not have been worked at all previously, were
opened, when it was found that the new machine could be relied upon to
raise the large quantities of water to be handled. The first engine in
Scotland was erected in 1720 at Elphinstone, in Stirlingshire. One was
put up in Hungary in 1723.
The first mine-engine, erected in 1712 at Griff, was 22 inches in
diameter, and the second and third engines were of similar size. That
erected at Ansthorpe was 23 inches in diameter of cylinder, and it was
a long time before much larger engines were constructed. Smeaton and
others finally made them as large as 6 feet in diameter.
In calculating the lifting-power of his engines, Newcomen's method was
"to square the diameter of the cylinder in inches, and, cutting off
the last figure, he called it 'long hundredweights;' then writing a
cipher on the right hand, he called the number on that side 'odd
pounds;' this he reckoned tolerably exact at a mean, or rather when
the barometer was above 30 inches, and the air heavy." In allowing for
frictional and other losses, he deducted from one-fourth to one-third.
Desaguliers found the rule quite exact. The usual mean pressure
resisting the motion of the piston averaged, in the best engines,
about 8 pounds per square inch of its area. The speed of the piston
was from 150 to 175 feet per minute. The temperature of the hot-well
was from 145 deg. to 175 deg. Fahr.
Smeaton made a number of test-trials of Newcomen engines to determine
their "duty"--i. e., to ascertain the expenditure of fuel required to
raise a definite quantity of water to a stated height. He found an
engine 10 inches in diameter of cylinder, and of 3 feet stroke, could
do work equal to raising 2,919,017 pounds of water one foot high, with
a bushel of coals weighing 84 pounds.
One of Smeaton's larger engines, erected at Long Benton, was 52 inches
in diameter of cylinder and of 7 feet stroke of piston, and made 12
strokes per minute. Its load was equal to 7-1/2 pounds per square inch
of piston-area, and its effective capacity about 40 horse-power. Its
duty was 9-1/2 millions of pounds raised one foot high per bushel of
coals. Its boiler evaporated 7.88 pounds of water per pound of fuel
consumed. It had 35 square feet of grate-surface and 142 square feet
of heating-surface beneath the boilers, and 317 square feet in the
flues--a total of 459 square feet. The moving parts of this engine
weighed 8-1/2 tons.
Smeaton erected one of these engines at the Chasewater mine, in
Cornwall, in 1775, which was of very considerable size. It was 6 feet
in diameter of steam-cylinder, and had a maximum stroke of piston of
9-1/2 feet. It usually worked 9 feet. The pumps were in three lifts of
about 100 feet each, and were 16-3/4 inches in diameter. Nine strokes
were made per minute. This engine replaced two others, of 64 and of 62
inches diameter of cylinder respectively, and both of 6 feet stroke.
One engine at the lower lift supplied the second, which was set above
it. The lower one had pumps 18-1/2 inches in diameter, and raised the
water 144 feet; the upper engine raised the water 156 feet, by pumps
17-1/2 inches in diameter. The later engine replacing them exerted
76-1/2 horse-power. There were three boilers, each 15 feet in
diameter, and having each 23 square feet of grate-surface. The chimney
was 22 feet high. The great beam, or "lever," of this engine was built
up of 20 beams of fir in two sets, placed side by side, and ten deep,
strongly bolted together. It was over 6 feet deep at the middle and 5
feet at the ends, and was 2 feet thick. The "main centres," or
journals, on which it vibrated were 8-1/2 inches in diameter and 8-1/2
inches long. The cylinder weighed 6-1/2 tons, and was paid for at the
rate of 28 shillings per hundredweight.
By the end of the eighteenth century, therefore, the engine of
Newcomen, perfected by the ingenuity of Potter and of Beighton, and by
the systematic study and experimental research of Smeaton, had become
a well-established form of steam-engine, and its application to
raising water had become general. The coal-mines of Coventry and of
Newcastle had adopted this method of drainage; and the tin and the
copper mines of Cornwall had been deepened, using, for drainage,
engines of the largest size.
Some engines had been set up in and about London, the scene of
Worcester's struggles and disappointments, where they were used to
supply water to large houses. Others were in use in other large cities
of England, where water-works had been erected.
Some engines had also been erected to drive mills indirectly by
raising water to turn water-wheels. This is said by Farey to have been
first practised in 1752, at a mill near Bristol, and became common
during the next quarter of a century. Many engines had been built in
England and sent across the channel, to be applied to the drainage of
mines on the Continent. Belidor[32] stated that the manufacture of
these "fire-engines" was exclusively confined to England; and this
remained true many years after his time. When used for the drainage of
mines, the engine usually worked the ordinary lift or bucket pump;
when employed for water-supply to cities, the force or plunger pump
was often employed, the engine being placed below the level of the
reservoir. Dr. Rees states that this engine was in common use among
the collieries of England as early as 1725.
[32] "Architecture Hydraulique," 1734.
The Edmonstone colliery was licensed, in 1725, to erect an engine, not
to exceed 28 inches diameter of cylinder and 9 feet stroke of piston,
paying a royalty of L80 per annum for eight years. This engine was
built in Scotland, by workmen sent from England, and cost about
L1,200. Its "great cost" is attributed to an extensive use of brass.
The workmen were paid their expenses and 15_s._ per week as wages. The
builders were John and Abraham Potter, of Durham. An engine built in
1775, having a steam-cylinder 48 inches in diameter and of 7 feet
stroke, cost about L2,000.
Smeaton found 57 engines at work near Newcastle in 1767, ranging in
size from 28 to 75 inches in diameter of cylinder, and of,
collectively, about 1,200 horse-power. Fifteen of these engines gave
an average of 98 square inches of piston to the horse-power, and the
average duty was 5,590,000 pounds raised 1 foot high by 1 bushel (84
pounds) of coal. The highest duty noted was 7.44 millions; the lowest
was 3.22 millions. The most efficient engine had a steam-cylinder 42
inches in diameter; the load was equivalent to 9-1/4 pounds per square
inch of piston-area, and the horse-power developed was calculated to
be 16.7.
Price, writing in 1778, says, in the Appendix to his "Mineralogia
Cornubiensis:" "Mr. Newcomen's invention of the fire-engine enabled us
to sink our mines to twice the depth we could formerly do by any other
machinery. Since this invention was completed, most other attempts at
its improvement have been very unsuccessful; but the vast consumption
of fuel in these engines is an immense drawback on the profit of our
mines, for every fire-engine of magnitude consumes L3,000 worth of
coals per annum. This heavy tax amounts almost to a prohibition."
Smeaton was given the description, in 1773, of a _stone_ boiler, which
was used with one of these engines at a copper mine at Camborne, in
Cornwall. It contained three copper flues 22 inches in diameter. The
gases were passed through these flues successively, finally passing
off to the chimney. This boiler was cemented with hydraulic mortar. It
was 20 feet long, 9 feet wide, and 8-1/2 feet deep. It was heated by
the waste heat from the roasting-furnaces. This was one of the
earliest flue-boilers ever made.
In 1780, Smeaton had a list of 18 large engines working in Cornwall.
The larger number of them were built by Jonathan Hornblower and John
Nancarron. At this time, the largest and best-known pumping-engine for
water-works was at York Buildings, in Villiers Street, Strand, London.
It had been in operation since 1752, and was erected beside one of
Savery's engines, built in 1710. It had a steam-cylinder 45 inches in
diameter, and a stroke of piston of 8 feet, making 7-1/2 strokes per
minute, and developing 35-1/2 horse-power. Its boiler was dome-shaped,
of copper, and contained a large central fire-box and a spiral flue
leading outward to the chimney. Another somewhat larger machine was
built and placed beside this engine, some time previous to 1775. Its
cylinder was 49 inches in diameter, and its stroke 9 feet. It raised
water 102 feet. This engine was altered and improved by Smeaton in
1777, and continued in use until 1813.
Smeaton, as early as 1765, designed a _portable_ engine,[33] in which
he supported the machinery on a wooden frame mounted on short legs and
strongly put together, so that the whole machine could be transported
and set at work wherever convenient.
[33] Smeaton's "Reports," vol. i., p. 223.
[Illustration: FIG. 23.--Smeaton's Portable-Engine Boiler, 1765.]
In place of the beam, a large pulley was used, over which a chain was
carried, connecting the piston with the pump-rod, and the motion was
similar to that given by the discarded beam. The wheel was supported
on A-frames, resembling somewhat the "gallows-frames" still used with
the beam-engines of American river-boats. The sills carrying the two
A's supported the cylinder. The injection-cistern was supported above
the great pulley-wheel. The valve-gearing and the injection-pump were
worked by a smaller wheel, mounted on the same axis with the larger
one. The boiler was placed apart from the engine, with which it was
connected by a steam-pipe, in which was placed the "regulator," or
throttle-valve. The boiler (Fig. 23) "was shaped like a large
tea-kettle," and contained a fire-box, _B_, or internal furnace, of
which the sides were made of cast-iron. The fire-door, _C_, was placed
on one side and opposite the flue, _D_, through which the products of
combustion were led to the chimney, _E_; a short, large pipe, _F_,
leading downward from the furnace to the outside of the boiler, was
the ash-pit. The shell of the boiler, _A_, was made of iron plate
one-quarter of an inch thick. The steam-cylinder of the engine was 18
inches in diameter, the stroke of piston 6 feet, the great wheel 6-1/2
feet in diameter, and the A-frames 9 feet high. The boiler was made 6
feet, the furnace 34 inches, and the grate 18 inches in diameter. The
piston was intended to make 10 strokes per minute, and the engine to
develop 4-1/8 horse-power.
In 1773, Smeaton prepared plans for a pumping-engine to be set up at
Cronstadt, the port of St. Petersburg, to empty the great dry dock
constructed by Peter the Great and Catherine, his successor. This
great dock was begun in 1719. It was large enough to dock ten of the
ships of that time, and had previously been imperfectly drained by two
great windmills 100 feet high. So imperfectly did they do their work,
that a _year_ was required to empty the dock, and it could therefore
only be used once in each summer. The engine was built at the Carron
Iron Works, in England. It had a cylinder 66 inches in diameter, and a
stroke of piston of 8-1/2 feet. The lift varied from 33 feet when the
dock was full to 53 feet when it was cleared of water. The load on the
engine averaged about 8-1/3 pounds per square inch of piston-area.
There were three boilers, each 10 feet in diameter, and 16 feet 4
inches high to the apex of its hemispherical dome. They contained
internal fire-boxes with grates of 20 feet area, and were surrounded
by flues helically traversing the masonry setting. The engine was
started in 1777, and worked very successfully.
The lowlands of Holland were, before the time of Smeaton, drained by
means of windmills. The uncertainty and inefficiency of this method
precluded its application to anything like the extent to which
steam-power has since been utilized. In 1440, there were 150 inland
lakes, or "_meers_," in that country, of which nearly 100, having an
extent of over 200,000 acres, have since been drained. The "Haarlemmer
Meer" alone covers nearly 50,000 acres, and forms the basin of a
drainage-area of between 200,000 and 300,000 acres, receiving a
rainfall of 54,000,000 tons, which must be raised 16 feet in
discharging it. The beds of these lakes are from 10 to 20 feet lower
than the water-level in the adjacent canals. In 1840, 12,000 windmills
were still employed in this work. In the following year, William II.,
at the suggestion of a commission, decreed that only steam-engines
should be employed to do this immense work. Up to this time the
average consumption of fuel for the pumping-engines in use is said to
have been 20 pounds per hour per horse-power.
The first engine used was erected in 1777 and 1778, on the Newcomen
plan, to assist the 34 windmills employed to drain a lake near
Rotterdam. This lake covered 7,000 acres, and its bed was 12 feet
below the surface of the river Meuse, which passes it, and empties
into the sea in the immediate neighborhood. The iron parts of the
engine were built in England, and the machine was put together in
Holland. The steam-cylinder was 52 inches in diameter, and the stroke
of piston 9 feet. The boiler was 18 feet in diameter, and contained a
double flue. The main beam was 27 feet long. The pumps were 6 in
number, 3 cylindrical and 3 having a square cross-section; 3 were of 6
feet and 3 of 2-1/2 feet stroke. Two pumps only were worked at
high-tide, and the others were added one at a time, as the tide fell,
until, at low-tide, all 6 were at work.
The size of this engine, and the magnitude of its work, seem
insignificant when compared with the machinery installed 60 years
later to drain the Haarlemmer Meer, and with the work done by the
last. These engines are 12 feet in diameter of cylinder and 10 feet
stroke of piston, and work--they are 3 in number--the one 11 pumps of
63 inches diameter and 10 feet stroke, the others 8 pumps of 73 inches
diameter and of the same length of stroke. The modern engines do a
"duty" of 75,000,000 to 87,000,000 with 94 pounds of coal, consuming
2-1/4 pounds of coal per hour and per horse-power.
The first steam-engine applied to working the blowing-machinery of a
blast-furnace was erected at the Carron Iron-Works, in Scotland, near
Falkirk, in 1765, and proved very unsatisfactory. Smeaton
subsequently, in 1769 or 1770, introduced better machinery into these
works and improved the old engine, and this use of the steam-engine
soon became usual. This engine did its work indirectly, furnishing
water, by pumping, to drive the water-wheels which worked the
blowing-cylinders. Its steam-cylinder was 6 feet in diameter, and the
pump-cylinder 52 inches. The stroke was 9 feet.
A direct-acting engine, used as a blowing-engine, was not constructed
until about 1784, at which time a single-acting blowing-cylinder, or
air-pump, was placed at the "out-board" end of the beam, where the
pump-rod had been attached. The piston of the air-cylinder was loaded
with the weights needed to force it down, expelling the air, and the
engine did its work in raising the loaded piston, the air-cylinder
filling as the piston rose. A large "accumulator" was used to equalize
the pressure of the expelled air. This consisted of another
air-cylinder, having a loaded piston which was left free to rise and
fall. At each expulsion of air by the blowing-engine this cylinder was
filled, the loaded piston rising to the top. While the piston of the
former was returning, and the air-cylinder was taking in its charge of
air, the accumulator would gradually discharge the stored air, the
piston slowly falling under its load. This piston was called the
"floating piston," or "fly-piston," and its action was, in effect,
precisely that of the upper portion of the common blacksmith's
bellows.
Dr. Robison, the author of "Mechanical Philosophy," one of the very
few works even now existing deserving such a title, describes one of
these engines[34] as working in Scotland in 1790. It had a
steam-cylinder 40 or 44 inches in diameter, a blowing-cylinder 60
inches in diameter, and the stroke of piston was 6 feet. The
air-pressure was 2.77 pounds per square inch as a maximum in the
blowing-cylinder; and the floating piston in the regulating-cylinder
was loaded with 2.63 pounds per square inch. Making 15 or 18 strokes
per minute, this engine delivered about 1,600 cubic feet of air, or
120-1/2 pounds in weight, per minute, and developed 20 horse-power.
[34] "Encyclopaedia Britannica," 1st edition.
At about the same date a change was made in the blowing-cylinder. The
air entered at the bottom, as before, but was forced out at the top,
the piston being fitted with valves, as in the common lifting-pump,
and the engine thus being arranged to do the work of expulsion during
the down-stroke of the steam-piston.
Four years later, the regulating-cylinder, or accumulator, was given
up, and the now familiar "water-regulator" was substituted for it.
This consists of a tank, usually of sheet-iron, set open-end downward
in a large vessel containing water. The lower edge of the inner tank
is supported on piers a few inches above the bottom of the large one.
The pipe carrying air from the blowing-engine passes above this
water-regulator, and a branch-pipe is led down into the inner tank. As
the air-pressure varies, the level of the water within the inverted
tank changes, rising as pressure falls at the slowing of the motion of
the piston, and falling as the pressure rises again while the piston
is moving with an accelerated velocity. The regulator, thus receiving
surplus air to be delivered when needed, greatly assists in regulating
the pressure. The larger the regulator, the more perfectly uniform the
pressure. The water-level outside the inner tank is usually five or
six feet higher than within it. This apparatus was found much more
satisfactory than the previously-used regulator, and, with its
introduction, the establishment of the steam-engine as a
blowing-engine for iron-works and at blast-furnaces may be considered
as having been fully established.
Thus, by the end of the third quarter of the eighteenth century, the
steam-engine had become generally introduced, and had been applied to
nearly all of the purposes for which a single-acting engine could be
used. The path which had been opened by Worcester had been fairly laid
out by Savery and his contemporaries, and the builders of the Newcomen
engine, with such improvements as they had been able to effect, had
followed it as far as they were able. The real and practical
introduction of the steam-engine is as fairly attributable to Smeaton
as to any one of the inventors whose names are more generally known in
connection with it. As a mechanic, he was unrivaled; as an engineer,
he was head and shoulders above any constructor of his time engaged in
general practice. There were very few important public works built in
Great Britain at that time in relation to which he was not consulted;
and he was often visited by foreign engineers, who desired his advice
with regard to works in progress on the Continent.
[Illustration]
CHAPTER III.
_THE DEVELOPMENT OF THE MODERN STEAM-ENGINE. JAMES WATT AND HIS
CONTEMPORARIES._
The world is now entering upon the Mechanical Epoch. There is
nothing in the future more sure than the great triumphs which that
epoch is to achieve. It has already advanced to some glorious
conquests. What miracles of invention now crowd upon us! Look
abroad, and contemplate the infinite achievements of the
steam-power.
And yet we have only begun--we are but on the threshold of this
epoch.... What is it but the setting of the great distinctive seal
upon the nineteenth century?--an advertisement of the fact that
society has risen to occupy a higher platform than ever before?--a
proclamation from the high places, announcing honor, honor immortal,
to the workmen who fill this world with beauty, comfort, and
power--honor to be forever embalmed in history, to be perpetuated in
monuments, to be written in the hearts of this and succeeding
generations!--KENNEDY.
SECTION I.--JAMES WATT AND HIS INVENTIONS.
The success of the Newcomen engine naturally attracted the attention
of mechanics, and of scientific men as well, to the possibility of
making other applications of steam-power.
The best men of the time gave much attention to the subject, but,
until James Watt began the work that has made him famous, nothing more
was done than to improve the proportions and slightly alter the
details of the Newcomen and Calley engine, even by such skillful
engineers as Brindley and Smeaton. Of the personal history of the
earlier inventors and improvers of the steam-engine, very little is
ascertained; but that of Watt has become well known.
[Illustration: James Watt.]
JAMES WATT was of an humble lineage, and was born at Greenock, then a
little Scotch fishing village, but now a considerable and a busy town,
which annually launches upon the waters of the Clyde a fleet of
steamships whose engines are probably, in the aggregate, far more
powerful than were all the engines in the world at the date of Watt's
birth, January 19, 1736. His grandfather, Thomas Watt, of
Crawfordsdyke, near Greenock, was a well-known mathematician about the
year 1700, and was for many years a schoolmaster at that place. His
father was a prominent citizen of Greenock, and was at various times
chief magistrate and treasurer of the town. James Watt was a bright
boy, but exceedingly delicate in health, and quite unable to attend
school regularly, or to apply himself closely to either study or play.
His early education was given by his parents, who were respectable and
intelligent people, and the tools borrowed from his father's
carpenter-bench served at once to amuse him and to give him a
dexterity and familiarity with their use that must undoubtedly have
been of inestimable value to him in after-life.
M. Arago, the eminent French philosopher, who wrote one of the
earliest and most interesting biographies of Watt, relates anecdotes
of him which, if correct, illustrate well his thoughtfulness and his
intelligence, as well as the mechanical bent of the boy's mind. He is
said, at the age of six years, to have occupied himself during leisure
hours with the solution of geometrical problems; and Arago discovers,
in a story in which he is described as experimenting with the
tea-kettle,[35] his earliest investigations of the nature and
properties of steam.
[35] The same story is told of Savery and of Worcester.
When finally sent to the village school, his ill health prevented his
making rapid progress; and it was only when thirteen or fourteen years
of age that he began to show that he was capable of taking the lead in
his class, and to exhibit his ability in the study, particularly, of
mathematics. His spare time was principally spent in sketching with
his pencil, in carving, and in working at the bench, both in wood and
metal. He made many ingenious pieces of mechanism, and some beautiful
models. His favorite work seemed to be the repairing of nautical
instruments. Among other pieces of apparatus made by the boy was a
very fine barrel-organ. In boyhood, as in after-life, he was a
diligent reader, and seemed to find something to interest him in every
book that came into his hands.
At the age of eighteen, Watt was sent to Glasgow, there to
reside with his mother's relatives, and to learn the trade of a
mathematical-instrument maker. The mechanic with whom he was placed
was soon found too indolent, or was otherwise incapable of giving
much aid in the project, and Dr. Dick, of the University of Glasgow,
with whom Watt became acquainted, advised him to go to London.
Accordingly, he set out in June, 1755, for the metropolis, where, on
his arrival, he arranged with Mr. John Morgan, in Cornhill, to work a
year at his chosen business, receiving as compensation 20 guineas. At
the end of the year he was compelled, by serious ill-health, to return
home.
Having become restored to health, he went again to Glasgow in 1756,
with the intention of pursuing his calling there. But, not being the
son of a burgess, and not having served his apprenticeship in the
town, he was forbidden by the guilds, or trades-unions, to open a shop
in Glasgow. Dr. Dick came to his aid, and employed him to repair some
apparatus which had been bequeathed to the college. He was finally
allowed the use of three rooms in the University building, its
authorities not being under the municipal rule. He remained here until
1760, when, the trades no longer objecting, he took a shop in the
city; and in 1761 moved again, into a shop on the north side of the
Trongate, where he earned a scanty living without molestation, and
still kept up his connection with the college. He did some work as a
civil engineer in the neighborhood of Glasgow, but soon gave up all
other employment, and devoted himself entirely to mechanics.
He spent much of his leisure time--of which he had, at first, more
than was desirable--in making philosophical experiments and in the
manufacture of musical instruments, in making himself familiar with
the sciences, and in devising improvements in the construction of
organs. In order to pursue his researches more satisfactorily, he
studied German and Italian, and read Smith's "Harmonics," that he
might become familiar with the principles of construction of musical
instruments. His reading was still very desultory; but the
introduction of the Newcomen engine in the neighborhood of Glasgow,
and the presence of a model in the college collections, which was
placed in his hands, in 1763, for repair, led him to study the history
of the steam-engine, and to conduct for himself an experimental
research into the properties of steam, with a set of improvised
apparatus.
Dr. Robison, then a student of the University, who found Watt's shop a
pleasant place in which to spend his leisure, and whose tastes
affiliated so strongly with those of Watt that they became friends
immediately upon making acquaintance, called the attention of the
instrument-maker to the steam-engine as early as 1759, and suggested
that it might be applied to the propulsion of carriages. Watt was at
once interested, and went to work on a little model, having tin
steam-cylinders and pistons connected to the driving-wheels by an
intermediate system of gearing. The scheme was afterwards given up,
and was not revived by Watt for a quarter of a century.
Watt studied chemistry, and was assisted by the advice and instruction
of Dr. Black, who was then making the researches which resulted in the
discovery of "latent heat." His proposal to repair the model Newcomen
engine in the college collections led to his study of Desaguliers's
treatise, and of the works of Switzer and others. He thus learned what
had been done by Savery and by Newcomen, and by those who had improved
the engine of the latter.
In his own experiments he used, at first, apothecaries' phials and
hollow canes for steam reservoirs and pipes, and later a Papin's
digester and a common syringe. The latter combination made a
non-condensing engine, in which he used steam at a pressure of 15
pounds per square inch. The valve was worked by hand, and Watt saw
that an automatic valve-gear only was needed to make a working
machine. This experiment, however, led to no practical result. He
finally took hold of the Newcomen model, which had been obtained from
London, where it had been sent for repairs, and, putting it in good
working order, commenced experiments with that.
The Newcomen model, as it happened, had a boiler which, although made
to a scale from engines in actual use, was quite incapable of
furnishing steam enough to work the engine. It was about nine inches
in diameter; the steam-cylinder was two inches in diameter, and of six
inches stroke of piston, arranged as in Fig. 24, which is a picture of
the model as it now appears. It is retained among the most
carefully-preserved treasures of the University of Glasgow.
[Illustration: FIG. 24.--The Newcomen Model.]
Watt made a new boiler for the experimental investigation on which he
was about to enter, and arranged it in such a manner that he could
measure the quantity of water evaporated and of steam used at every
stroke of the engine.
He soon discovered that it required but a very small quantity of steam
to heat a very large quantity of water, and immediately attempted to
determine with precision the relative weights of steam and water in
the steam-cylinder when condensation took place at the down-stroke of
the engine, and thus independently proved the existence of that
"latent heat," the discovery of which constitutes, also, one of the
greatest of Dr. Black's claims to distinction. Watt at once went to
Dr. Black and related the remarkable fact which he had thus detected,
and was, in turn, taught by Black the character of the phenomenon as
it had been explained to his classes by the latter some little time
previously. Watt found that, at the boiling-point, his steam,
condensing, was capable of heating six times its weight of water such
as was used for producing condensation.
Perceiving that steam, weight for weight even, was a vastly greater
absorbent and reservoir of heat than water, Watt saw plainly the
importance of taking greater care to economize it than had previously
been customary. He first attempted to economize in the boiler, and
made boilers with wooden "shells," in order to prevent losses by
conduction and radiation, and used a larger number of flues to secure
more complete absorption of the heat from the furnace-gases. He also
covered his steam-pipes with non-conducting materials, and took every
precaution that his ingenuity could devise to secure complete
utilization of the heat of combustion. He soon found, however, that he
was not working at the most important point, and that the great source
of loss was to be found in defects which he noted in the action of the
steam in the cylinder. He soon concluded that the sources of loss of
heat in the Newcomen engine--which would be greatly exaggerated in a
small model--were:
First, the dissipation of heat by the cylinder itself, which was of
brass, and was both a good conductor and a good radiator.
Secondly, the loss of heat consequent upon the necessity of cooling
down the cylinder at every stroke, in producing the vacuum.
Thirdly, the loss of power due to the pressure of vapor beneath the
piston, which was a consequence of the imperfect method of
condensation.
He first made a cylinder of non-conducting material--wood soaked in
oil and then baked--and obtained a decided advantage in economy of
steam. He then conducted a series of very accurate experiments upon
the temperature and pressure of steam at such points on the scale as
he could readily reach, and, constructing a curve with his results,
the abscesses representing temperatures and the pressures being
represented by the ordinates, he ran the curve backward until he had
obtained closely-approximate measures of temperatures less than 212 deg.,
and pressures less than atmospheric. He thus found that, with the
amount of injection-water used in the Newcomen engine, bringing the
temperature of the interior, as he found, down to from 140 deg. to 175 deg.
Fahr., a very considerable back-pressure would be met with.
Continuing his examination still further, he measured the amount of
steam used at each stroke, and, comparing it with the quantity that
would just fill the cylinder, he found that at least _three-fourths
was wasted_. The quantity of cold water necessary to produce the
condensation of a given weight of steam was next determined; and he
found that one pound of steam contained enough heat to raise about six
pounds of cold water, as used for condensation, from the temperature
of 52 deg. to the boiling-point; and, going still further, he found that
he was compelled to use, at each stroke of the Newcomen engine, _four
times as much injection-water as should suffice to condense a cylinder
full of steam_. This confirmed his previous conclusion that
three-fourths of the heat supplied to the engine was wasted.
Watt had now, therefore, determined by his own researches, as he
himself enumerates them,[36] the following facts:
[36] Robison's "Mechanical Philosophy," edited by Brewster.
"1. The capacities for heat of iron, copper, and of some sorts of
wood, as compared with water.
"2. The bulk of steam compared with that of water.
"3. The quantity of water evaporated in a certain boiler by a pound of
coal.
"4. The elasticities of steam at various temperatures greater than
that of boiling water, and an approximation to the law which it
follows at other temperatures.
"5. How much water in the form of steam was required every stroke by a
small Newcomen engine, with a wooden cylinder 6 inches in diameter and
12 inches stroke.
"6. The quantity of cold water required in every stroke to condense
the steam in that cylinder, so as to give it a working-power of about
7 pounds on the square inch."
After these well-devised and truly scientific investigations, Watt was
enabled to enter upon his work of improving the steam-engine with an
intelligent understanding of its existing defects, and with a
knowledge of their cause. Watt soon saw that, in order to reduce the
losses in the working of the steam in the steam-cylinder, it would be
necessary to find some means, as he said, to keep the cylinder "always
as hot as the steam that entered it," notwithstanding the great
fluctuations of temperature and pressure of the steam during the up
and the down strokes. He has told us how, finally, the happy thought
occurred to him which relieved him of all difficulty, and led to the
series of modifications which at last gave to the world the modern
type of steam-engine.
He says:[37] "I had gone to take a walk on a fine Sabbath afternoon. I
had entered the Green by the gate at the foot of Charlotte street, and
had passed the old washing-house. I was thinking upon the engine at
the time, and had gone as far as the herd's house, when the idea came
into my mind that, as steam was an elastic body, it would rush into a
vacuum, and, if a communication were made between the cylinder and an
exhausted vessel, it would rush into it, and might be there condensed
without cooling the cylinder. I then saw that I must get rid of the
condensed steam and injection-water if I used a jet, as in Newcomen's
engine. Two ways of doing this occurred to me: First, the water might
be run off by a descending pipe, if an offlet could be got at the
depth of 35 or 36 feet, and any air might be extracted by a small
pump. The second was, to make the pump large enough to extract both
water and air." "I had not walked farther than the Golf-house, when
the whole thing was arranged in my mind."
[37] "Reminiscences of James Watt," Robert Hart; "Transactions of
the Glasgow Archaeological Society," 1859.
Referring to this invention, Watt said to Prof. Jardine:[38] "When
analyzed, the invention would not appear so great as it seemed to be.
In the state in which I found the steam-engine, it was no great effort
of mind to observe that the quantity of fuel necessary to make it work
would forever prevent its extensive utility. The next step in my
progress was equally easy--to inquire what was the cause of the great
consumption of fuel. This, too, was readily suggested, viz., the waste
of fuel which was necessary to bring the whole cylinder, piston, and
adjacent parts from the coldness of water to the heat of steam, no
fewer than from 15 to 20 times in a minute." It was by pursuing this
train of thought that he was led to devise the separate condenser.
[38] "Lives of Boulton and Watt," Smiles.
On Monday morning Watt proceeded to make an experimental test of his
new invention, using for his steam-cylinder and piston a large brass
surgeon's-syringe, 1-3/4-inch diameter and 10 inches long. At each end
was a pipe leading steam from the boiler, and fitted with a cock to
act as a steam-valve. A pipe led also from the top of the cylinder to
the condenser, the syringe being inverted and the piston-rod hanging
downward for convenience. The condenser was made of two pipes of thin
tin plate, 10 or 12 inches long, and about one-sixth of an inch in
diameter, standing vertically, and having a connection at the top
with a horizontal pipe of larger size, and fitted with a
"snifting-valve." Another vertical pipe, about an inch in diameter,
was connected to the condenser, and was fitted with a piston, with a
view to using it as an "air-pump." The whole was set in a cistern of
cold water. The piston-rod of the little steam-cylinder was drilled
from end to end to permit the water to be removed from the cylinder.
This little model (Fig. 25) worked very satisfactorily, and the
perfection of the vacuum was such that the machine lifted a weight of
18 pounds hung upon the piston-rod, as in the sketch. A larger model
was immediately afterward constructed, and the result of its test
confirmed fully the anticipations which had been awakened by the first
experiment.
[Illustration: FIG. 25.--Watt's Experiment.]
Having taken this first step and made such a radical improvement, the
success of this invention was no sooner determined than others
followed in rapid succession, as consequences of the exigencies
arising from the first change in the old Newcomen engine. But in the
working out of the forms and proportions of the details of the new
engine, even Watt's powerful mind, stored as it was with
happily-combined scientific and practical information, was occupied
for years. In attaching the separate condenser, he first attempted
surface-condensation; but this not succeeding well, he substituted the
jet. Some provision became at once necessary for preventing the
filling of the condenser with water.
Watt at first intended adopting the expedient which had worked
satisfactorily with the less effective condensation of Newcomen's
engine--i. e., leading a pipe from the condenser to a depth greater
than the height of a column of water which could be counterbalanced by
the pressure of the atmosphere; but he subsequently employed the
air-pump, which relieves the condenser not only of the water, but of
the air which also usually collects in considerable volume in the
condenser, and vitiates the vacuum. He next substituted oil and tallow
for water in the lubrication of the piston and keeping it steam-tight,
in order to avoid the cooling of the cylinder incident to the use of
the latter. Another cause of refrigeration of the cylinder, and
consequent waste of power in its operation, was seen to be the
entrance of the atmosphere, which followed the piston down the
cylinder at each stroke, cooling its interior by its contact. This the
inventor concluded to prevent by covering the top of the cylinder,
allowing the piston-rod to play through a "stuffing-box"--which device
had long been known to mechanics.
He accordingly not only covered the top, but surrounded the whole
cylinder with an external casing, or "steam-jacket," and allowed the
steam from the boiler to pass around the steam-cylinder and to press
upon the upper surface of the piston, where its pressure was variable
at pleasure, and therefore more manageable than that of the
atmosphere. It also, besides keeping the cylinder hot, could do
comparatively little harm should it leak by the piston, as it could be
condensed, and thus readily disposed of.
When he had concluded to build the larger experimental engine, Watt
determined to give his whole time and attention to the work, and hired
a room in an old deserted pottery near the Broomielaw. Here he worked
with a mechanic--John Gardiner, whom he had taken into his
employ--uninterruptedly for many weeks. Meantime, through his friend
Dr. Black, probably, he had made the acquaintance of Dr. Roebuck, a
wealthy physician, who had, with other Scotch capitalists, just
founded the celebrated Carron Iron-Works, and had opened a
correspondence with him, in which he kept that gentleman informed of
the progress of his work on the new engine.
This engine had a steam-cylinder, Watt tells us, of "five or six"
inches diameter, and of two feet stroke. It was of copper,
smooth-hammered, but not bored out, and "not very true." This was
encased in another cylinder of wood. In August, 1765, he tried the
small engine, and wrote Dr. Roebuck that he had had "good success,"
although the machine was very imperfect. "On turning the
exhausting-cock, the piston, when not loaded, ascended as quick as the
blow of a hammer, and as quick when loaded with 18 pounds (being 7
pounds on the inch) as it would have done if it had had an injection
as usual." He then tells his correspondent that he was about to make
the larger model. In October, 1765, he finished the latter. The
engine, when ready for trial, was still very imperfect. It
nevertheless did good work for so rude a machine.
Watt was now reduced to poverty, and, after borrowing considerable
sums from friends, he was finally compelled to give up his scheme for
the time, and to seek employment in order to provide for his family.
During an interval of about two years he supported himself by
surveying, and by the work of exploring coal-fields in the
neighborhood of Glasgow for the magistrates of the city. He did not,
however, entirely give up his invention.
In 1767, Dr. Roebuck assumed Watt's liabilities to the amount of
L1,000, and agreed to provide capital for the prosecution of his
experiments and to introduce his invention; and, on the other hand,
Watt agreed to surrender to Dr. Roebuck two-thirds of the patent.
Another engine was next built, having a steam-cylinder seven or eight
inches in diameter, which was finished in 1768. This worked
sufficiently well to induce the partners to ask for a patent, and the
specifications and drawings were completed and presented in 1769.
Watt also built and set up several Newcomen engines, partly, perhaps,
to make himself thus thoroughly familiar with the practical details of
engine-building. Meantime, also, he prepared the plans for, and
finally had built, a moderately large engine of his own new type. Its
steam-cylinder was 18 inches in diameter, and the stroke of piston was
5 feet. This engine was built at Kinneil, and was finished in
September, 1769. It was not all satisfactory in either its
construction or its operation. The condenser was a surface-condenser
composed of pipes somewhat like that used in his first little model,
and did not prove to be satisfactorily tight. The steam-piston leaked
seriously, and repeated trials only served to make more evident its
imperfections. He was assisted in this time of need by both Dr. Black
and Dr. Roebuck; but he felt strongly the risks which he ran of
involving his friends in serious losses, and became very despondent.
Writing to Dr. Black, he says: "Of all things in life, there is
nothing more foolish than inventing;" and probably the majority of
inventors have been led to the same opinion by their own experiences.
"Misfortunes never come singly;" and Watt was borne down by the
greatest of all misfortunes--the loss of a faithful and affectionate
wife--while still unable to see a successful issue of his schemes.
Only less disheartening than this was the loss of fortune of his
steadfast friend, Dr. Roebuck, and the consequent loss of his aid. It
was at about this time, in the year 1769, that negotiations were
commenced which resulted in the transfer of the capitalized interest
in Watt's engine to the wealthy manufacturer whose name, coupled with
that of Watt, afterward became known throughout the civilized world,
as the steam-engine in its new form was pushed into use by his energy
and business tact.
Watt met Mr. Boulton, who next became his partner, in 1768, on his
journey to London to procure his patent, and the latter had then
examined Watt's designs, and, at once perceiving their value, proposed
to purchase an interest. Watt was then unable to reply definitely to
Boulton's proposition, pending his business arrangements with Dr.
Roebuck; but, with Roebuck's consent, afterwards proposed that Boulton
should take a one-third interest with himself and partner, paying
Roebuck therefor one-half of all expenses previously incurred, and
whatever he should choose to add to compensate "for the risk he had
run." Subsequently, Dr. Roebuck proposed to transfer to Boulton and to
Dr. Small, who was desirous of taking interest with Boulton, one-half
of his proprietorship in Watt's inventions, on receiving "a sum not
less than one thousand pounds," which should, after the experiments on
the engine were completed, be deemed "just and reasonable." Twelve
months were allowed for the adjustment of the account. This proposal
was accepted in November, 1769.
[Illustration: Matthew Boulton.]
MATTHEW BOULTON, who now became a partner with James Watt, was the son
of a Birmingham silver stamper and piecer, and succeeded to his
father's business, building up a great establishment, which, as well
as its proprietor, was well known in Watt's time. Watt, writing to Dr.
Roebuck before the final arrangement had been made, urged him to close
with Boulton for "the following considerations:
"1st. From Mr. Boulton's own character as an ingenious, honest, and
rich man. 2dly. From the difficulty and expense there would be of
procuring accurate and honest workmen and providing them with proper
utensils, and getting a proper overseer or overseers. If, to avoid
this inconvenience, you were to contract for the work to be done by a
master-workman, you must give up a great share of the profit. 3dly.
The success of the engine is far from being verified. If Mr. Boulton
takes his chance of success from the account I shall write Dr. Small,
and pays you any adequate share of the money laid out, it lessens your
risk, and in a greater proportion than I think it will lessen your
profits. 4thly. The assistance of Mr. Boulton's and Dr. Small's
ingenuity (if the latter engage in it) in improving and perfecting the
machine may be very considerable, and may enable us to get the better
of the difficulties that might otherwise damn it. Lastly, consider my
uncertain health, my irresolute and inactive disposition, my inability
to bargain and struggle for my own with mankind: all which disqualify
me for any great undertaking. On our side, consider the first outlay
and interest, the patent, the present engine, about L200 (though there
would not be much loss in making it into a common engine), two years
of my time, and the expense of models."
Watt's estimate of the value of Boulton's ingenuity and talent was
well-founded. Boulton had shown himself a good scholar, and had
acquired considerable knowledge of the languages and of the sciences,
particularly of mathematics, after leaving the school from which he
graduated into the shop when still a boy. In the shop he soon
introduced a number of valuable improvements, and he was always on the
lookout for improvements made by others, with a view to their
introduction in his business. He was a man of the modern style, and
never permitted competitors to excel him in any respect, without the
strongest efforts to retain his leading position. He always aimed to
earn a reputation for good work, as well as to make money. His
father's workshop was at Birmingham; but Boulton, after a time, found
that his rapidly-increasing business would compel him to find room for
the erection of a more extensive establishment, and he secured land at
Soho, two miles distant from Birmingham, and there erected his new
manufactory, about 1762.
The business was, at first, the manufacture of ornamental metal-ware,
such as metal buttons, buckles, watch-chains, and light filigree and
inlaid work. The manufacture of gold and silver plated-ware was soon
added, and this branch of business gradually developed into a very
extensive manufacture of works of art. Boulton copied fine work
wherever he could find it, and often borrowed vases, statuettes, and
bronzes of all kinds from the nobility of England, and even from the
queen, from which to make copies. The manufacture of inexpensive
clocks, such as are now well known throughout the world as an article
of American trade, was begun by Boulton. He made some fine
astronomical and valuable ornamental clocks, which were better
appreciated on the Continent than in England. The business of the Soho
manufactory in a few years became so extensive, that its goods were
known to every civilized nation, and its growth, under the management
of the enterprising, conscientious, and ingenious Boulton, more than
kept pace with the accumulation of capital; and the proprietor found
himself, by his very prosperity, often driven to the most careful
manipulation of his assets, and to making free use of his credit.
Boulton had a remarkable talent for making valuable acquaintances, and
for making the most of advantages accruing thereby. In 1758 he made
the acquaintance of Benjamin Franklin, who then visited Soho; and in
1766 these distinguished men, who were then unaware of the existence
of James Watt, were corresponding, and, in their letters, discussing
the applicability of steam-power to various useful purposes. Between
the two a new steam-engine was designed, and a model was constructed
by Boulton, which was sent to Franklin and exhibited by him in London.
Dr. Darwin seems to have had something to do with this scheme, and the
enthusiasm awakened by the promise of success given by this model may
have been the origin of the now celebrated prophetic rhymes so often
quoted from the works of that eccentric physician and poet. Franklin
contributed, as his share in the plan, an idea of so arranging the
grate as to prevent the production of smoke. He says: "All that is
necessary is to make the smoke of fresh coals pass descending through
those that are already ignited." His idea has been, by more recent
schemers, repeatedly brought forward as new. Nothing resulted from
these experiments of Boulton, Franklin, and Darwin, and the plan of
Watt soon superseded all less well-developed plans.
In 1767, Watt visited Soho and carefully inspected Boulton's
establishment. He was very favorably impressed by the admirable
arrangement of the workshops and the completeness of their outfit, as
well as by the perfection of the organization and administration of
the business. In the following year he again visited Soho, and this
time met Boulton, who had been absent at the previous visit. The two
great mechanics were mutually gratified by the meeting, and each at
once acquired for the other the greatest respect and esteem. They
discussed Watt's plans, and Boulton then definitely decided not to
continue his own experiments, although he had actually commenced the
construction of a pumping-engine. With Dr. Small, who was also at
Soho, Watt discussed the possibility of applying his engine to the
propulsion of carriages, and to other purposes. On his return home,
Watt continued his desultory labors on his engines, as already
described; and the final completion of the arrangement with Boulton,
which immediately followed the failure of Dr. Roebuck, took place some
time later.
Before Watt could leave Scotland to join his partner at Soho, it was
necessary that he should finish the work which he had in hand,
including the surveys of the Caledonian canal, and other smaller
works, which he had had in progress some months. He reached Birmingham
in the spring of 1774, and was at once domiciled at Soho, where he set
at work upon the partly-made engines which had been sent from Scotland
some time previously. They had laid, unused and exposed to the
weather, at Kinneil three years, and were not in as good order as
might have been desired. The _block-tin_ steam-cylinder was probably
in good condition, but the iron parts were, as Watt said, "perishing,"
while he had been engaged in his civil engineering work. At leisure
moments, during this period, Watt had not entirely neglected his plans
for the utilization of steam. He had given much thought, and had
expended some time, in experiments upon the plan of using it in a
rotary or "wheel" engine. He did not succeed in contriving any plan
which seemed to promise success.
It was in November, 1774, that Watt finally announced to his old
partner, Dr. Roebuck, the successful trial of the Kinneil engine. He
did not write with the usual enthusiasm and extravagance of the
inventor, for his frequent disappointments and prolonged suspense had
very thoroughly extinguished his vivacity. He simply wrote: "The
fire-engine I have invented is now going, and answers much better than
any other that has yet been made; and I expect that the invention will
be very beneficial to me."
The change of the "atmospheric engine" of Newcomen into the modern
steam-engine was now completed in its essential details. The first
engine which was erected at Kinneil, near Boroughstoness, had a
steam-cylinder 18 inches in diameter. It is seen in the accompanying
sketch.
[Illustration: FIG. 26.--Watt's Engine, 1774.]
In Fig. 26, the steam passes from the boiler through the pipe _d_ and
the valve _c_ to the cylinder-casing or steam-jacket, _Y Y_, and above
the piston, _b_, which it follows in its descent in the cylinder,
_a_, the valve _f_ being at this time open, to allow the exhaust into
the condenser, _h_.
The piston now being at the lower end of the cylinder, and the
pump-rods at the opposite end of the beam, _y_, being thus raised and
the pumps filled with water, the valves _c_ and _f_ close, while _e_
opens, allowing the steam which remains above the piston to flow
beneath it, until, the pressures becoming equal above and below, the
weight of the pump-rods overbalancing that of the piston, the latter
is rapidly drawn to the top of the cylinder, while the steam is
displaced above, passing to the under-side of the piston.
The valve _e_ is next closed, and _c_ and _f_ are again opened; the
down-stroke is repeated. The water and air entering the condenser are
removed at each stroke by the air-pump, _i_, which communicates with
the condenser by the passage _s_. The pump _q_ supplies
condensing-water, and the pump _A_ takes away a part of the water of
condensation, which is thrown by the air-pump into the "hot-well,"
_k_, and from it the feed-pump supplies the boiler. The valves are
moved by valve-gear very similar to Beighton's and Smeaton's, by the
pins, _m m_, in the "plug-frame" or "tappet-rod," _n n_.
The engine is mounted upon a substantial foundation, _B B_. _F_ is an
opening out of which, before starting the engine, the air is driven
from the cylinder and condenser.
The inventions covered by the patent of 1769 were described as
follows:
"My method of lessening the consumption of steam, and consequently
fuel, in fire-engines, consists in the following principles:
"1st. That the vessel in which the powers of steam are to be employed
to work the engine--which is called 'the cylinder' in common
fire-engines, and which I call 'the steam-vessel'--must, during the
whole time that the engine is at work, be kept as hot as the steam
which enters it; first, by inclosing it in a case of wood, or any
other materials that transmit heat slowly; secondly, by surrounding
it with steam or other heated bodies; and thirdly, by suffering
neither water nor other substances colder than the steam to enter or
touch it during that time.
"2dly. In engines that are to be worked, wholly or partially, by
condensation of steam, the steam is to be condensed in vessels
distinct from the steam-vessel or cylinder, though occasionally
communicating with them. These vessels I call condensers; and while
the engines are working, these _condensers_ ought at least to be kept
as cold as the air in the neighborhood of the engines, by application
of water or other cold bodies.
"3dly. Whatever air or other elastic vapor is not condensed by the
cold of the condenser, and may impede the working of the engine, is to
be drawn out of the steam-vessels or condensers by means of pumps,
wrought by the engines themselves, or otherwise.
"4thly. I intend in many cases to employ the expansive force of steam
to press on the pistons, or whatever may be used instead of them, in
the same manner as the pressure of the atmosphere is now employed in
common fire-engines. In cases where cold water cannot be had in
plenty, the engines may be wrought by this force of steam only, by
discharging the steam into the open air after it has done its office.
"5thly. Where motions round an axis are required, I make the
steam-vessels in form of hollow rings or circular channels, with
proper inlets and outlets for the steam, mounted on horizontal axles
like the wheels of a water-mill. Within them are placed a number of
valves that suffer any body to go round the channel in one direction
only. In these steam-vessels are placed weights, so fitted to them as
to fill up a part or portion of their channels, yet rendered capable
of moving freely in them by the means hereinafter mentioned or
specified. When the steam is admitted in these engines between these
weights and the valves, it acts equally on both, so as to raise the
weight on one side of the wheel, and, by the reaction of the valves
successively, to give a circular motion to the wheel, the valves
opening in the direction in which the weights are pressed, but not in
the contrary. As the vessel moves round, it is supplied with steam
from the boiler, and that which has performed its office may either be
discharged by means of condensers, or into the open air.
"6thly. I intend in some cases to apply a degree of cold not capable
of reducing the steam to water, but of contracting it considerably, so
that the engines shall be worked by the alternate expansion and
contraction of the steam.
"Lastly, instead of using water to render the piston or other parts of
the engine air or steam-tight, I employ oils, wax, resinous bodies,
fat of animals, quicksilver, and other metals, in their fluid state."
In the construction and erection of his engines, Watt still had great
difficulty in finding skillful workmen to make the parts with
accuracy, to fit them with care, and to erect them properly when once
finished. And the fact that both Newcomen and Watt met with such
serious trouble, indicates that, even had the engine been designed
earlier, it is quite unlikely that the world would have seen the
steam-engine a success until this time, when mechanics were just
acquiring the skill requisite for its construction. But, on the other
hand, it is not at all improbable that, had the mechanics of an
earlier period been as skillful and as well-educated in the manual
niceties of their business, the steam-engine might have been much
earlier brought into use.
In the time of the Marquis of Worcester it would have probably been
found impossible to obtain workmen to construct the steam-engine of
Watt, had it been then invented. Indeed, Watt, upon one occasion,
congratulated himself that one of his steam-cylinders only lacked
_three-eighths_ of an inch of being truly cylindrical.
The history of the steam-engine is from this time a history of the
work of the firm of Boulton & Watt. Newcomen engines continued to be
built for years after Watt went to Soho, and by many builders. A host
of inventors still worked on the most attractive of all mechanical
combinations, seeking to effect further improvements. Some inventions
were made by contemporaries of Watt, as will be seen hereafter, which
were important as being the germs of later growths; but these were
nearly all too far in advance of the time, and nearly every successful
and important invention which marked the history of steam-power for
many years originated in the fertile brain of James Watt.
The defects of the Newcomen engine were so serious, that it was no
sooner known that Boulton of Soho had become interested in a new
machine for raising water by steam-power, than inquiries came to him
from all sides, from mine-owners who were on the point of being
drowned out, and from proprietors whose profits were absorbed by the
expense of pumping, and who were glad to pay the L5 per horse-power
per year finally settled upon as royalty. The London municipal
water-works authorities were also ready to negotiate for
pumping-engines for raising water to supply the metropolis. The firm
was therefore at once driven to make preparations for a large
business.
The first and most important matter, however, was to secure an
extension of the patent, which was soon to expire. If not renewed, the
15 years of study and toil, of poverty and anxiety, through which Watt
had toiled, would prove profitless to the inventor, and the fruits of
his genius would have become the unearned property of others. Watt
saw, at one time, little hope of securing the necessary act of
Parliament, and was greatly tempted to accept a position tendered him
by the Russian Government, upon the solicitation of his old friend,
Dr. Robison, then a Professor of Mathematics at the Naval School at
Cronstadt. The salary was L1,000--a princely income for a man in
Watt's circumstances, and a peculiar temptation to the needy
mechanic.
Watt, however, went to London, and, with the help of his own and of
Boulton's influential friends, succeeded in getting his bill through.
His patent was extended 24 years, and Boulton & Watt set about the
work of introducing their engines with the industry and enterprise
which characterized their every act.
In the new firm, Boulton took charge of the general business, and Watt
superintended the design, construction, and erection of their engines.
Boulton's business capacity, with Watt's wonderful mechanical
ability--Boulton's physical health, and his vigor and courage,
offsetting Watt's feeble health and depression of spirits--and, more
than all, Boulton's pecuniary resources, both in his own purse and in
those of his friends, enabled the firm to conquer all difficulties,
whether in finance, in litigation, or in engineering.
It was only after the successful erection and operation of several
engines that Boulton and Watt became legally partners. The understood
terms were explicitly stated by Watt to include an assignment to
Boulton of two-thirds the patent-right; Boulton paying all expenses,
advancing stock in trade at an appraised valuation, on which it was to
draw interest; Watt making all drawings and designs, and drawing
one-third net profits.
As soon as Watt was relieved of the uncertainties regarding his
business connections, he married a second wife, who, as Arago says, by
"her various talent, soundness of judgment, and strength of
character," made a worthy companion to the large-hearted and
large-brained engineer. Thenceforward his cares were only such as
every business-man expects to be compelled to sustain, and the next
ten years were the most prolific in inventions of any period in Watt's
life.
From 1775 to 1785 the partners acquired five patents, covering a large
number of valuable improvements upon the steam-engine, and several
independent inventions. The first of these patents covered the now
familiar and universally-used copying-press for letters, and a
machine for drying cloth by passing it between copper rollers filled
with steam of sufficiently high temperature to rapidly evaporate the
moisture. This patent was issued February 14, 1780.
[Illustration: FIG. 27.--Watt's Engine, 1781.]
In the following year, October 25, 1781, Watt patented five devices by
which he obtained the rotary motion of the engine-shaft without the
use of a crank. One of these was the arrangement shown in Fig. 27, and
known as the "sun-and-planet" wheels. The crank-shaft carries a
gear-wheel, which is engaged by another securely fixed upon the end of
the connecting-rod. As the latter is compelled to revolve about the
axis of the shaft by a tie which confines the connecting-rod end at a
fixed distance from the shaft, the shaft-gear is compelled to revolve,
and the shaft with it. Any desired velocity-ratio was secured by
giving the two gears the necessary relative diameters. A fly-wheel was
used to regulate the motion of the shaft.[39] Boulton & Watt used the
sun-and-planet device on many engines, but finally adopted the crank,
when the expiration of the patent held by Matthew Wasborough, and
which had earlier date than Watt's patent of 1781, permitted them.
Watt had proposed the use of a crank, it is said, as early as 1771,
but Wasborough anticipated him in securing the patent. Watt had made a
model of an engine with a crank and fly-wheel, and he has stated that
one of his workmen, who had seen the model, described it to
Wasborough, thus enabling the latter to deprive Watt of his own
property. The proceeding excited great indignation on the part of
Watt; but no legal action was taken by Boulton & Watt, as the
overthrow of the patent was thought likely to do them injury by
permitting its use by more active competitors and more ingenious men.
[39] For the privilege of using the fly-wheel to regulate the motion
of the engine, Boulton & Watt paid a royalty to Matthew Wasborough,
who had patented it, and who held also the patent for its
combination with a crank, as invented by Pickard and Steed.
The next patent issued to Watt was an exceedingly important one, and
of especial interest in a history of the development of the economical
application of steam. This patent included:
1. The expansion of steam, and six methods of applying the principle
and of equalizing the expansive power.
2. The double-acting steam-engine, in which the steam acts on each
side of the piston alternately, the opposite side being in
communication with the condenser.
3. The double or coupled steam-engine--two engines capable of working
together, or independently, as may be desired.
4. The use of a rack on the piston-rod, working into a sector on the
end of the beam, thus securing a perfect rectilinear motion of the
rod.
5. A rotary engine, or "steam-wheel."
The efficiency to be secured by the expansion of steam had long been
known to Watt, and he had conceived the idea of economizing some of
that power, the waste of which was so plainly indicated by the violent
rushing of the exhaust-steam into the condenser, as early as 1769.
This was described in a letter to Dr. Small, of Birmingham, in May of
that year. When experimenting at Kinneil, he had tried to determine
the real value of the principle by trial on his small engine.
Boulton had also recognized the importance of this improved method of
working steam, and their earlier Soho engines were, as Watt said, made
with cylinders "double the size wanted, and cut off the steam at
half-stroke." But, though "this was a great saving of steam, so long
as the valves remained as at first," the builders were so constantly
annoyed by alterations of the valves by proprietors and their
engineers, that they finally gave up that method of working, hoping
ultimately to be able to resume it when workmen of greater
intelligence and reliability could be found. The patent was issued
July 17, 1782.
Watt specified a cut-off at one-quarter stroke as usually best.
Watt's explanation of the method of economizing by expansive working,
as given to Dr. Small,[40] is worthy of reproduction. He says: "I
mentioned to you a method of still doubling the effect of steam, and
that tolerably easy, by using the power of steam rushing into a
vacuum, at present lost. This would do a little more than double the
effect, but it would too much enlarge the vessels to use it all. It is
peculiarly applicable to wheel-engines, and may supply the want of a
condenser where force of steam is only used; for, open one of the
steam-valves and admit steam, until one-fourth of the distance between
it and the next valve is filled with steam, shut the valve, and the
steam will continue to expand and to pass round the wheel with a
diminishing power, ending in one-fourth its first exertion. The sum of
this series you will find greater than one-half, though only
one-fourth steam was used. The power will indeed be unequal, but this
can be remedied by a fly, or in several other ways."
[40] "Lives of Boulton and Watt," Smiles.
It will be noticed that Watt suggests, above, the now well-known
non-condensing engine. He had already, as has been seen, described it
in his patent of 1769, as also the rotary engine.
Watt illustrates and explains his idea very neatly, by a sketch
similar to that here given (Fig. 28).
Steam, entering the cylinder at _a_, is admitted until one-fourth the
stroke has been made, when the steam-valve is closed, and the
remainder of the stroke is performed without further addition of
steam. The variation of steam-pressure is approximately inversely
proportional to the variation of its volume. Thus, at half-stroke, the
pressure becomes one-half that at which the steam was supplied to the
cylinder. At the end of the stroke it has fallen to one-fourth the
initial pressure. The pressure is always nearly equal to the product
of the initial pressure and volume divided by the volume at the given
instant. In symbols,
_PV_
_P'_ = ----.
_V'_
It is true that the condensation of steam doing work changes this law
in a marked manner; but the condensation and reevaporation of steam,
due to the transfer of heat to and from the metal of the cylinder,
tends to compensate the first variation by a reverse change of
pressure with change of volume.
[Illustration: FIG. 28.--Expansion of Steam.]
The sketch shows this progressive variation of pressure as expansion
proceeds. It is seen that the work done per unit of volume of steam as
taken from the boiler is much greater than when working without
expansion. The product of the mean pressure by the volume of the
cylinder is less, but the quotient obtained by dividing this quantity
by the volume or weight of steam taken from the boiler, is much
greater with than without expansion. For the case assumed and
illustrated, the work done during expansion is one and two-fifths
times that done previous to cutting off the steam, and the work done
per pound of steam is 2.4 times that done without expansion.
Were there no losses to be met with and to be exaggerated by the use
of steam expansively, the gain would become very great with moderate
expansion, amounting to twice the work done when "following" full
stroke, when the steam is cut off at one-seventh. The estimated gain
is, however, never realized. Losses by friction, by conduction and
radiation of heat, and by condensation and reevaporation in the
cylinder--of which losses the latter are most serious--after passing a
point which is variable, and which is determined by the special
conditions in each case, augment with greater rapidity than the gain
by expansion.
In actual practice, it is rarely found, except where special
precautions are taken to reduce these losses, that economy follows
expansion to a greater number of volumes than about one-half the
square root of the steam-pressure; i. e., about twice for 15 or 20
pounds pressure, three times for about 30 pounds, and four and five
times for 60 or 65 and for 100 to 125 pounds respectively. Watt very
soon learned this general principle; but neither he, nor even many
modern engineers, seem to have learned that too great expansion often
gives greatly-reduced economy.
The inequality of pressure due to expansion, to which he refers, was a
source of much perplexity to Watt, as he was for a long time convinced
that he must find some method of "equalizing" the consequent irregular
effort of the steam upon the piston. The several methods of
"equalizing the expansive power" which are referred to in the patent
were attempts to secure this result. By one method, he shifted the
centre as the beam vibrated, thus changing the lengths of the arms of
that great lever, to compensate the change of moment consequent upon
the change of pressure. He finally concluded that a fly-wheel, as
first proposed by Fitzgerald, who advised its use on Papin's engine,
would be the best device on engines driving a crank, and trusted to
the inertia of a balance-weight in his pumping-engines, or to the
weight of the pump-rods, and permitted the piston to take its own
speed so far as it was not thus controlled.
The double-acting engine was a modification of the single-acting
engine, and was very soon determined upon after the successful working
of the latter had become assured.
Watt had covered in the top of his single-acting engine, to prevent
cooling the interior of the cylinder by contact with the comparatively
cold atmosphere. When this had been done, there was but a single step
required to convert the machine into the double-acting engine. This
alteration, by which the steam was permitted to act upon the upper and
the lower sides of the piston alternately, had been proposed by Watt
as early as 1767, and a drawing of the engine was laid before a
committee of the House of Commons in 1774-'75. By this simple change
Watt doubled the power of his engine. Although invented much earlier,
the plan was not patented until he was, as he states, driven to take
out the patent by the "plagiarists and pirates" who were always ready
to profit by his ingenuity. This form of engine is now almost
universally used. The single-acting pumping-engine remains in use in
Cornwall, and in a few other localities, and now and then an engine is
built for other purposes, in which steam acts only on one side of the
piston; but these are rare exceptions to the general rule.
The subject of his next invention was not less interesting. The
double-cylinder or "compound" engine has now, after the lapse of
nearly a century, become an important and usual type of engine. It is
impossible to determine precisely to whom to award the credit of its
first conception. Dr. Falk, in 1779, had proposed a double-acting
engine, in which there were two single-acting cylinders, acting in
opposite directions and alternately on opposite sides of a wheel, with
which a rack on the piston-rod of each geared.
Watt claimed that Hornblower, the patentee of the "compound engine,"
was an infringer upon his patents; and, holding the patent on the
separate condenser, he was able to prevent the engine of his
competitor taking such form as to be successfully introduced. The
Hornblower engine was soon given up.
Watt stated that this form of engine had been invented by him as early
as 1767, and that he had explained its peculiarities to Smeaton and
others several years before Hornblower attempted to use it. He wrote
to Boulton: "It is no less than our double-cylinder engine, worked
upon our principle of expansion." He never made use of the plan,
however; and the principal object sought, apparently, in patenting
this, as well as many other devices, was to secure himself against
competition.
The rack and sector patented at this time was soon superseded by the
parallel-motion; and the last claim, the "steam-wheel" or rotary
engine, although one was built of considerable size, was not
introduced.
After the patent of 1782 had been secured, Watt turned his attention,
when not too hard-pressed by business, to other schemes, and to
experimenting with still other modifications and applications of his
engine. He had, as early as 1777, proposed to make a steam-hammer for
Wilkinson's forge; but he was too closely engaged with more important
matters to take hold of the project with much earnestness until late
in the year 1782, when, after some preliminary trials, he reported,
December 13th: "We have tried our little tilting-forge hammer at Soho
with success. The following are some of the particulars: Cylinder, 15
inches in diameter; 4 feet stroke; strokes per minute, 20. The
hammer-head, 120 pounds weight, rises 8 inches, and strikes 240 blows
per minute. The machine goes quite regularly, and can be managed as
easily as a water-mill. It requires a very small quantity of
steam--not above half the contents of the cylinder per stroke. The
power employed is not more than one-fourth of what would be required
to raise the quantity of water which would enable a water-wheel to
work the same hammer with the same velocity."
He immediately set about making a much heavier hammer, and on April
26, 1783, he wrote that he had done "a thing never done
before"--making his hammer strike 300 blows a minute. This hammer
weighed 7-1/2 hundredweight, and had a drop of 2 feet. The
steam-cylinder had a diameter of 42 inches and 6 feet stroke of
piston, and was calculated to have sufficient power to drive four
hammers weighing 7 hundredweight each. The engine made 20 strokes per
minute, the hammer giving 90 blows in the same time.
This new application of steam-power proving successful, Watt next
began to develop a series of minor inventions, which were finally
secured by his patent of April 27, 1784, together with the steam
tilt-hammer, and a steam-carriage, or "locomotive engine."
The contrivance previously used for guiding the head of the
piston-rod--the sectors and chains, or rack--had never given
satisfaction. The rudeness of design of the contrivance was only
equalled by its insecurity. Watt therefore contrived a number of
methods of accomplishing the purpose, the most beautiful and
widely-known of which is the "parallel-motion," although it has now
been generally superseded by one of the other devices patented at the
same time--the cross-head and guides. As originally proposed, a rod
was attached to the head of the piston-rod, standing vertically when
the latter was at quarter-stroke. The upper end of this rod was
pivoted to the end of the beam, and the lower end to the extremity of
a horizontal rod having a length equal to one-half the length of the
beam. The other end of the horizontal rod was coupled to the frame of
the engine. As the piston rose and fell, the upper and lower ends of
the vertical rod were swayed in opposite directions, and to an equal
extent, by the beam and the lower horizontal rod, the middle point at
which the piston-rod was attached preserving its position in the
vertical line. This form was objectionable, as the whole effort of the
engine was transmitted through the parallel-motion rods. Another form
is shown in the sketch given of the double-acting engine in Fig. 31,
which was free from this defect. The head of the piston-rod, _g_, was
guided by rods connecting it with the frame at _c_, and forming a
"parallelogram," _g d e b_, with the beam. Many varieties of
"parallel-motion" have been devised since Watt's invention was
attached to his engines at Soho. They usually are more or less
imperfect, guiding the piston-rod in a line only approximately
straight.
The cross-head and guides are now generally used, very much as
described by Watt in this patent as his "second principle." This
device will be seen in the engravings given hereafter of more modern
engines. The head of the piston-rod is fitted into a transverse bar,
or cross-head, which carries properly-shaped pieces at its
extremities, to which are bolted "gibs," so made as to fit upon guides
secured to the engine-frame. These guides are adjusted to precise
parallelism with the centre line of the cylinder. The cross-head,
sliding in or on these guides, moves in a perfectly straight line,
and, compelling the piston-rod to move with it, the latter is even
more perfectly guided than by a parallel-motion. This arrangement,
where properly proportioned, is not necessarily subject to great
friction, and is much more easily adjusted and kept in line than the
parallel-motion when wear occurs or maladjustment takes place.
By the same patent, Watt secured the now common "puppet-valve" with
beveled seat, and the application of the steam-engine to driving
rolling-mills and hammers for forges, and to "wheel-carriages for
removing persons or goods, or other matters, from place to place." For
the latter purpose he proposes to use boilers "of wood, or of thin
metal, strongly secured by hoops or otherwise," and containing
"internal fire-boxes." He proposed to use a condenser cooled by
currents of air.
It would require too much space to follow Watt in all his schemes for
the improvement and for the application of the steam-engine. A few of
the more important and more ingenious only can be described. Many of
the contracts of Boulton & Watt gave them, as compensation for their
engines, a fraction--usually one-third--of the value of the fuel saved
by the use of the Watt engine in place of the engine of Newcomen, the
amount due being paid annually or semiannually, with an option of
redemption on the part of the purchaser at ten years' purchase. This
form of agreement compelled a careful determination, often, of the
work done and fuel consumed by both the engine taken out and that put
in its place. It was impossible to rely upon any determination by
personal observation of the number of strokes made by the engine. Watt
therefore made a "counter," like that now familiar to every one as
used on gas-meters. It consists of a train of wheels moving pointers
on several dials, the first dial showing tens, the second hundreds,
the third thousands, etc., strokes or revolutions. Motion was
communicated to the train by means of a pendulum, the whole being
mounted on the beam of the engine, where every vibration produced a
swing of the pendulum. Eight dials were sometimes used, the counter
being set and locked, and only opened once a year, when the time
arrived for determining the work done during the preceding
twelve-month.
The application of his engine to purposes for which careful adjustment
of speed was requisite, or where the load was subject to considerable
variation, led to the use of a controlling-valve in the steam-pipe,
called the "throttle-valve," which was adjustable by hand, and
permitted the supply of steam to the engine to be adjusted at any
instant and altered to any desired extent. It is now given many forms,
but it still is most usually made just as originally designed by Watt.
It consists of a circular disk, which just closes up the steam-pipe
when set directly across it, or of an elliptical disk, which closes
the pipe when standing at an angle of somewhat less than 90 deg. with the
line of the pipe. This disk is carried on a spindle extending through
the pipe at one side, and carrying on its outer end an arm by means
of which it may be turned into any position. When placed with its face
in line with the pipe, it offers very little resistance to the flow of
steam to the engine. When set in the other position, it shuts off
steam entirely and stops the engine. It is placed in such position at
any time, that the speed of the engine is just that required at the
time. In the engraving of the double-acting engine with fly-wheel
(Fig. 31), it is shown at _T_, as controlled by the governor.
[Illustration: FIG. 29.--The Governor.]
The governor, or "fly-ball governor," as it is often distinctively
called, was another of Watt's minor but very essential inventions. Two
heavy iron or brass balls, _B B'_, were suspended from pins, _C C'_,
in a little cross-piece carried on the head of a vertical spindle, _A
A'_, driven by the engine. The speed of the engine varying, that of
the spindle changed correspondingly, and the faster the balls were
swung the farther they separated. When the engine's speed decreased,
the period of revolution of the balls was increased, and they fell
back toward the spindle. Whenever the velocity of the engine was
uniform, the balls preserved their distance from the spindle and
remained at the same height, their altitude being determined by the
relation existing between the force of gravity and centrifugal force
in the temporary position of equilibrium. The distance from the point
of suspension down to the level of the balls is always equal to 9.78
inches divided by the square of the number of revolutions per
second--i. e., _h_ = 9.78 (1/_N_^2) = 0.248 (1/_N_^2) meters.
The arms carrying the balls, or the balls themselves, are pinned to
rods, _M M'_, which are connected to a piece, _N N'_, sliding loosely
on the spindle. A score, _T_, cut in this piece engages a lever, _V_,
and, as the balls rise and fall, a rod, _W_, is moved, closing and
opening the throttle-valve, and thus adjusting the supply of steam in
such a way as to preserve a nearly fixed speed of engine. The
connection with the throttle-valve and with the cut-off valve-gear is
seen not only in the engraving of the double-acting Watt engine, but
also in those of the Greene and the Corliss engines. This contrivance
had previously been used in regulating water-wheels and windmills.
Watt's invention consisted in its application to the regulation of the
steam-engine.
Still another useful invention of Watt's was his "mercury
steam-gauge"--a barometer in which the height of the mercury was
determined by the pressure of the steam instead of that of the
atmosphere. This simple instrument consisted merely of a bent tube
containing a portion of mercury. One leg, _B D_, of this U-tube was
connected with the steam-pipe, or with the boiler by a small
steam-pipe; the other end, _C_, was open to the atmosphere. The
pressure of the steam on the mercury in _B D_ caused it to rise in the
other "leg" to a height exactly proportioned to the pressure, and
causing very nearly two inches difference of level to the pound, or
one inch to the pound actual rise in the outer leg. The rude sketch
from Farey, here given (Fig. 30), indicates sufficiently well the form
of this gauge. It is still considered by engineers the most reliable
of all forms of steam-gauge. Unfortunately, it is not conveniently
applicable at high pressure. The scale, _A_, is marked with numbers
indicating the pressure, which numbers are indicated by the head of a
rod floating up with the mercury.
A similar gauge was used to determine the degree of perfection of
vacuum attained in the condenser, the mercury falling in the outer leg
as the vacuum became more complete. A perfect vacuum would cause a
depression of level in that leg to 30 inches below the level of the
mercury in the leg connected with the condenser. In a more usual form,
it consisted of a simple glass tube having its lower end immersed in a
cistern of mercury, as in the ordinary barometer, the top of the tube
being connected with a pipe leading to the condenser. With a perfect
vacuum in the condenser, the mercury would rise in the tube very
nearly 30 inches. Ordinarily, the vacuum is not nearly perfect, and, a
back pressure remaining in the condenser of one or two pounds per
square inch, the atmospheric pressure remaining unbalanced is only
sufficient to raise the mercury 26 or 28 inches above the level of the
liquid metal in the cistern.
[Illustration: FIG. 30. Mercury Steam Gauge. Glass Water Gauge.]
To determine the height of water in his boiler, Watt added to the
gauge-cocks already long in use the "glass water-gauge," which is
still seen in nearly every well-arranged boiler. This was a glass
tube, _a a'_ (Fig. 30), mounted on a standard attached to the front of
the boiler, and at such a height that its middle point was very little
below the proposed water-level. It was connected by a small pipe, _r_,
at the top to the steam-space, and another little pipe, _r'_, led into
the boiler from its lower end below the water-line. As the water rose
and fell within the boiler, its level changed correspondingly in the
glass. This little instrument is especially liked, because the
position of the water is at all times shown to the eye of the
attendant. If carefully protected against sudden changes of
temperature, it answers perfectly well with even very high pressures.
The engines built by Boulton & Watt were finally fitted with the crank
and fly-wheel for application to the driving of mills and machinery.
The accompanying engraving (Fig. 31) shows the engine as thus made,
combining all of the essential improvements designed by its inventor.
In the engraving, _C_ is the steam-cylinder, _P_ the piston, connected
to the beam by the link, _g_, and guided by the parallel-motion, _g d
c_. At the opposite end of the beam a connecting-rod, _O_, connects
with the crank and fly-wheel shaft. _R_ is the rod of the air-pump, by
means of which the condenser is kept from being flooded by the water
used for condensation, which water-supply is regulated by an
"injection-handle," _E_. A pump-rod, _N_, leads down from the beam to
the cold-water pump, by which water is raised from the well or other
source to supply the needed injection-water. The air-pump rod also
serves as a "plug-rod," to work the valves, the pins at _m_ and _R_
striking the lever, _m_, at either end of the stroke. When the piston
reaches the top of the cylinder, the lever, _m_, is raised, opening
the steam-valve, _B_, at the top, and the exhaust-valve, _E_, at the
bottom, and at the same time closing the exhaust at the top and the
steam at the bottom. When the entrance of steam at the top and the
removal of steam-pressure below the piston has driven the piston to
the bottom, the pin, _R_, strikes the lever, _m_, opening the steam
and closing the exhaust valve at the bottom, and similarly reversing
the position of the valves at the top. The position of the valves is
changed in this manner with every reversal of the motion of the piston
as the crank "turns over the centre."
[Illustration: FIG. 31.--Boulton & Watt's Double-Acting Engine, 1784.]
The earliest engines of the double-acting kind, and of any
considerable size, which were built to turn a shaft, were those which
were set up in the Albion Mills, near Blackfriars' Bridge, London, in
1786, and destroyed when the mills burned down in 1791. There were a
pair of these engines (shown in Fig. 27), of 50 horse-power each, and
geared to drive 20 pairs of stones, making fine flour and meal.
Previous to the erection of this mill the power in all such
establishments had been derived from windmills and water-wheels. This
mill was erected by Boulton & Watt, and capitalists working with
them, not only to secure the profit anticipated from locating a
flour-mill in the city of London, but also with a view to exhibiting
the capacity of the new double-acting "rotating" engine. The plan was
proposed in 1783, and work was commenced in 1784; but the mill was not
set in operation until the spring of 1786. The capacity of the mill
was, in ordinary work, 16,000 bushels of wheat ground into fine flour
per week. On one occasion, the mill turned out 3,000 bushels in 24
hours. In the construction of the machinery of the mill, many
improvements upon the then standard practice were introduced,
including cast-iron gearing with carefully-formed teeth and iron
framing. It was here that John Rennie commenced his work, after
passing through his apprenticeship in Scotland, sending his chief
assistant, Ewart, to superintend the erection of the milling
machinery. The mill was a success as a piece of engineering, but a
serious loss was incurred by the capitalists engaged in the
enterprise, as it was set on fire a few years afterward and entirely
destroyed. Boulton and Watt were the principal losers, the former
losing L6,000, and the latter L3,000.
The valve-gear of this engine, a view of which is given in Fig. 27,
was quite similar to that used on the Watt pumping-engine. The
accompanying illustration (Fig. 32) represents this valve-motion as
attached to the Albion Mills engine.
[Illustration: FIG. 32.--Valve-Gear of the Albion Mills Engine.]
The steam-pipe, _a b d d e_, leads the steam from the boiler to the
chambers, _b_ and _e_. The exhaust-pipe, _g g_, leads from _h_ and _i_
to the condenser. In the sketch, the upper steam and the lower exhaust
valves, _b_ and _f_, are opened, and the steam-valve, _e_, and
exhaust-valve, _c_, are closed, the piston being near the upper end of
the cylinder and descending. _l_ represents the plug-frame, which
carries tappets, 2 and 3, which engage the lever, _s_, at either end
of its throw, and turn the shaft, _u_, thus opening and closing _c_
and _e_ simultaneously by means of the connecting-links, 13 and 14. A
similar pair of tappets on the opposite side of the plug-rod move the
valves, _b_ and _f_, by means of the rods, 10 and 11, the arm, _r_,
when struck by those tappets, turning the shaft, _t_, and thus moving
the arms to which those rods are attached. Counterbalance-weights,
carried on the ends of the arms, 4 and 15, retain the valves on their
seats when closed by the action of the tappets. When the piston nearly
reaches the lower end of the cylinder, the tappet, 1, engages the arm,
_r_, closing the steam-valve, _b_, and the next instant shutting the
exhaust-valve, _f_. At the same time, the tappet, 3, by moving the
arm, _s_, downward, opens the steam-valve, _e_, and the exhaust-valve,
_c_. Steam now no longer issues from the steam-pipe into the space,
_c_, and thence into the engine-cylinder (not shown in the sketch);
but it now enters the engine through the valve, _e_, forcing the
piston upwards. The exhaust is simultaneously made to occur at the
upper end, the rejected steam passing from the engine into the space,
_c_, and thence through _c_ and the pipe, _g_, into the condenser.
This kind of valve-gear was subsequently greatly improved by Murdoch,
Watt's ingenious and efficient foreman, but it is now entirely
superseded on engines of this class by the eccentric, and the various
forms of valve-gear driven by it.
[Illustration: FIG. 33.--Watt's Half-Trunk Engine, 1784.]
The "trunk-engine" was still another of the almost innumerable
inventions of Watt. A half-trunk engine is described in his patent of
1784, as shown in the accompanying sketch (Fig. 33), in which _A_ is
the cylinder, _B_ the piston, and _C_ its rod, encased in the
half-trunk, _D_. The plug-rod, _G_, moves the single pair of valves by
striking the catches, _E_ and _F_, as was usual with Watt's earlier
engines.
Watt's steam-hammer was patented at the same time. It is seen in Fig.
34, in which _A_ is the steam-cylinder and _B_ its rod, the engine
being evidently of the form just described. It works a beam, _C C_,
which in turn, by the rod, _M_, works the hammer-helve, _L J_, and the
hammer, _L_. The beam, _F G_, is a spring, and the block, _N_, the
anvil.
[Illustration: FIG. 34.--The Watt Hammer, 1784.]
Watt found it impossible to determine the duty of his engines at all
times by measurement of the work itself, and endeavored to find a way
of ascertaining the power produced, by ascertaining the pressure of
steam within the cylinder. This pressure was so variable, and subject
to such rapid as well as extreme fluctuations, that he found it
impossible to make use of the steam-gauge constructed for use on the
boiler. He was thus driven to invent a special instrument for this
work, which he called the "steam-engine indicator." This consisted of
a little steam-cylinder containing a nicely-fitting piston, which
moved without noticeable friction through a range which was limited by
the compression of a helical spring, by means of which the piston was
secured to the top of its cylinder. The distance through which the
piston rose was proportional to the pressure exerted upon it, and a
pointer attached to its rod traversed a scale upon which the pressure
per square inch could be read. The lower end of the instrument being
connected with the steam-cylinder of the engine by a small pipe
fitted with a cock, the opening of the latter permitted steam from the
engine-cylinder to fill the indicator-cylinder, and the pressure of
steam was always the same in both cylinders. The indicator-pointer
therefore traversed the pressure-scale, always exhibiting the pressure
existing at the instant in the cylinder of the engine. When the engine
was at rest and steam off, the indicator-piston stood at the same
level as when detached from the engine, and the pointer stood at 0 on
the scale. When steam entered, the piston rose and fell with the
fluctuations of pressure; and when the exhaust-valve opened,
discharging the steam and producing a vacuum in the steam-cylinder,
the pointer of the indicator dropped below 0, showing the degree of
exhaustion. Mr. Southern, one of Watt's assistants, fitted the
instrument with a sliding board, moved horizontally backward and
forward by a cord or link-work connecting directly or indirectly with
the engine-beam, and thus giving it a motion coincident with that of
the piston. This board carried a piece of paper, upon which a pencil
attached to the indicator piston-rod drew a curve. The vertical height
of any point on this curve above the base-line measured the pressure
in the cylinder at the moment when it was made, and the horizontal
distance of the point from either end of the diagram determined the
position, at the same moment, of the engine-piston. The curve thus
inscribed, called the "indicator card," or indicator diagram,
exhibiting every minute change in the pressure of steam in the engine,
not only enabled the mean pressure and the power of the engine to be
determined by its measurement, but, to the eye of the expert engineer,
it was a perfectly legible statement of the position of the valves of
the engine, and revealed almost every defect in the action of the
engine which could not readily be detected by external examination. It
has justly been called the "engineers' stethoscope," opening the
otherwise inaccessible parts of the steam-engine to the inspection of
the engineer even more satisfactorily than the stethoscope of the
physician gives him a knowledge of the condition and working of organs
contained within the human body. This indispensable and now familiar
engineers' instrument has since been modified and greatly improved in
detail.
The Watt engine had, by the construction of the improvements described
in the patents of 1782-'85, been given its distinctive form, and the
great inventor subsequently did little more than improve it by
altering the forms and proportions of its details. As thus practically
completed, it embodied nearly all the essential features of the modern
engine; and, as we have seen, the marked features of our latest
practice--the use of the double cylinder for expansion, the cut-off
valve-gear, and surface-condensation--had all been proposed, and to a
limited extent introduced. The growth of the steam-engine has here
ceased to be rapid, and the changes which followed the completion of
the work of James Watt have been minor improvements, and rarely, if
ever, real developments.
Watt's mind lost none of its activity, however, for many years. He
devised and patented a "smoke-consuming furnace," in which he led the
gases produced on the introduction of fresh fuel over the already
incandescent coal, and thus burned them completely. He used two fires,
which were coaled alternately. Even when busiest, also, he found time
to pursue more purely scientific studies. With Boulton, he induced a
number of well-known scientific men living near Birmingham to join in
the formation of a "Lunar Society," to meet monthly at the houses of
its members, "at the full of the moon." The time was thus fixed in
order that those members who came from a distance should be able to
drive home, after the meetings, by moonlight. Many such societies were
then in existence in England; but that at Birmingham was one of the
largest and most distinguished of them all. Boulton, Watt, Drs. Small,
Darwin, and Priestley, were the leaders, and among their occasional
visitors were Herschel, Smeaton, and Banks. Watt called these meetings
"Philosophers' meetings." It was during the period of most active
discussion at the "philosophers' meetings" that Cavendish and
Priestley were experimenting with mixtures of oxygen and hydrogen, to
determine the nature of their combustion. Watt took much interest in
the subject, and, when informed by Priestley that he and Cavendish had
both noticed a deposit of moisture invariably succeeding the explosion
of the mixed gases, when contained in a cold vessel, and that the
weight of this water was approximately equal to the weight of the
mixed gases, he at once came to the conclusion that the union of
hydrogen with oxygen produced water, the latter being a chemical
compound, of which the former were constituents. He communicated this
reasoning, and the conclusions to which it had led him, to Boulton, in
a letter written in December, 1782, and addressed a letter some time
afterward to Priestley, which was to have been read before the Royal
Society in April, 1783. The letter was not read, however, until a year
later, and, three months after, a paper by Cavendish, making the same
announcement, had been laid before the Society. Watt stated that both
Cavendish and Lavoisier, to whom also the discovery is ascribed,
received the idea from him.
The action of chlorine in bleaching organic coloring-matters, by (as
since shown) decomposing them and combining with their hydrogen, was
made known to Watt by M. Berthollet, the distinguished French chemist,
and the former immediately introduced its use into Great Britain, by
inducing his father-in-law, Mr. Macgregor, to make a trial of it.
The copartnership of Boulton & Watt terminated by limitation, and with
the expiration of the patents under which they had been working, in
the first year of the present century; and both partners, now old and
feeble, withdrew from active business, leaving their sons to renew the
agreement and to carry on the business under the same firm-style.
Boulton, however, still interested himself in some branches of
manufacture, especially in his mint, where he had coined many years
and for several nations.
Watt retired, a little later, to Heathfield, where he passed the
remainder of his life in peaceful enjoyment of the society of his
friends, in studies of all current matters of interest in science, as
well as in engineering. One by one his old friends died--Black in
1799, Priestley, an exile to America, in 1803, and Robison a little
later. Boulton died, at the age of eighty-one, August 17, 1809, and
even the loss of this nearest and dearest of his friends outside the
family was a less severe blow than that of his son Gregory, who died
in 1804.
Yet the great engineer and inventor was not depressed by the
loneliness which was gradually coming upon him. He wrote: "I know that
all men must die, and I submit to the decrees of Nature, I hope, with
due reverence to the Disposer of events;" and neglected no opportunity
to secure amusement or instruction, and kept body and mind constantly
occupied. He still attended the weekly meetings of the club, meeting
Rennie and Telford, and other distinguished men of his own and the
succeeding generation. He lost nothing of his fondness for invention,
and spent many months in devising a machine for copying statuary,
which he had not perfected to his own satisfaction at the time of his
death, ten years later. This machine was a kind of pentagraph, which
could be worked in any plane, and in which the marking-pencil gave
place to a cutting-tool. The tracing-point followed the surface of the
pattern, while the cutting-point, following its motion precisely,
formed a fac-simile in the material operated upon.
In the year 1800 he invented the water-main which was laid down by the
Glasgow Water-Works Company across the Clyde. The joints were
spherical and articulated, like those of the lobster's tail.
His workshop, of which a sketch is hereafter given, as drawn by the
artist Skelton, was in the garret of his house, and was well supplied
with tools and all kinds of laboratory material. His lathe and his
copying-machine were placed before the window, and his writing-desk in
the corner. Here he spent the greater part of his leisure time, often
even taking his meals in the little shop, rather than go to the table
for them. Even when very old, he occasionally made a journey to London
or Glasgow, calling on his old friends and studying the latest
engineering devices and inspecting public works, and was everywhere
welcomed by young and old as the greatest living engineer, or as the
kind and wise friend of earlier days.
He died August 19, 1819, in the eighty-third year of his age, and was
buried in Handsworth Church. The sculptor Chantrey was employed to
place a fitting monument above his grave, and the nation erected a
statue of the great man in Westminster Abbey.
This sketch of the greatest of all the inventors of the steam-engine
has been given no greater length than its subject justifies. Whether
we consider Watt as the inventor of the standard steam-engine of the
nineteenth century, as the scientific investigator of the physical
principles upon which the invention is based, or as the builder and
introducer of the most powerful known instrument by which the "great
sources of power in Nature are converted, adapted, and applied for the
use and convenience of man," he is fully entitled to preeminence. His
character as a man was no less admirable than as an engineer.
Smiles, Watt's most conscientious and indefatigable biographer,
writes:[41]
[41] "Life of Watt," p. 512.
[Illustration: FIG. 35.--James Watt's Workshop. (From Smiles's "Lives
of Boulton and Watt.")]
"Some months since, we visited the little garret at Heathfield in
which Watt pursued the investigations of his later years. The room had
been carefully locked up since his death, and had only once been swept
out. Everything lay very much as he left it. The piece of iron which
he was last employed in turning, lay on the lathe. The ashes of the
last fire were in the grate; the last bit of coal was in the scuttle.
The Dutch oven was in its place over the stove, and the frying-pan in
which he cooked his meals was hanging on its accustomed nail. Many
objects lay about or in the drawers, indicating the pursuits which had
been interrupted by death--busts, medallions, and figures, waiting to
be copied by the copying-machine--many medallion-moulds, a store of
plaster-of-Paris, and a box of plaster casts from London, the contents
of which do not seem to have been disturbed. Here are Watt's ladles
for melting lead, his foot-rule, his glue-pot, his hammer. Reflecting
mirrors, an extemporized camera with the lenses mounted on pasteboard,
and many camera-glasses laid about, indicate interrupted experiments
in optics. There are quadrant-glasses, compasses, scales, weights, and
sundry boxes of mathematical instruments, once doubtless highly
prized. In one place a model of the governor, in another of the
parallel-motion, and in a little box, fitted with wooden cylinders
mounted with paper and covered with figures, is what we suppose to be
a model of his calculating-machine. On the shelves are minerals and
chemicals in pots and jars, on which the dust of nearly half a century
has settled. The moist substances have long since dried up; the putty
has been turned to stone, and the paste to dust. On one shelf we come
upon a dish in which lies a withered bunch of grapes. On the floor, in
a corner, near to where Watt sat and worked, is a hair-trunk--a
touching memorial of a long-past love and a long-dead sorrow. It
contains all poor Gregory's school-books, his first attempts at
writing, his boy's drawings of battles, his first school-exercises
down to his college-themes, his delectuses, his grammars, his
dictionaries, and his class-books--brought into this retired room,
where the father's eye could rest upon them. Near at hand is the
sculpture-machine, on which he continued working to the last. Its
wooden frame is worm-eaten, and dropping into dust, like the hands
that made it. But though the great workman is gone to rest, with all
his griefs and cares, and his handiwork is fast crumbling to decay,
the spirit of his work, the thought which he put into his inventions,
still survives, and will probably continue to influence the destinies
of his race for all time to come."
The visitor to Westminster Abbey will find neither monarch, nor
warrior, nor statesman, nor poet, honored with a nobler epitaph than
that which is inscribed on the pedestal of Chantrey's monument to
Watt:
NOT TO PERPETUATE A NAME,
WHICH MUST ENDURE WHILE THE PEACEFUL ARTS FLOURISH,
BUT TO SHOW
THAT MANKIND HAVE LEARNT TO HONOR THOSE WHO BEST DESERVE THEIR
GRATITUDE,
THE KING,
HIS MINISTERS, AND MANY OF THE NOBLES AND COMMONERS OF THE REALM,
RAISED THIS MONUMENT TO
JAMES WATT,
WHO, DIRECTING THE FORCE OF AN ORIGINAL GENIUS,
EARLY EXERCISED IN PHILOSOPHIC RESEARCH,
TO THE IMPROVEMENT OF
THE STEAM-ENGINE,
ENLARGED THE RESOURCES OF HIS COUNTRY, INCREASED THE POWER OF MAN,
AND ROSE TO AN EMINENT PLACE
AMONG THE MOST ILLUSTRIOUS FOLLOWERS OF SCIENCE AND THE REAL
BENEFACTORS OF THE WORLD.
BORN AT GREENOCK, MDCCXXXVI.
DIED AT HEATHFIELD, IN STAFFORDSHIRE, MDCCCXIX.
[Illustration: Tomb of James Watt.]