THE STEAM ENGINE.
HERO’S ENGINE, AND OTHER EARLY STEAM ENGINES--WATT’S STEAM
ENGINE--THE CUT-OFF--GIFFARD INJECTOR--BOURDON’S STEAM GAUGE--FEED-
WATER HEATERS, SMOKE CONSUMERS, ETC.--ROTARY ENGINES--STEAM HAMMER--
STEAM FIRE ENGINE--COMPOUND ENGINES--SCHLICK AND TAYLOR SYSTEMS OF
BALANCING MOMENTUM OF MOVING PARTS--STATISTICS.
When the primeval man first turned upon himself the critical light of
introspection, and observed his own deficiencies, there were born within
him both the desire and the determination to supplement his weakness,
and become the ruling factor in the world’s destiny. The strength of his
arm unaided could not cope with that of the wild beast, he could not
travel so fast as the animal, nor soar so high as the bird, nor traverse
the waters of the sea like the fish. The magnificent power of the
elements first inspired him with awe, then was worshiped as a god, and
he trembled in his weakness. Then he began to invent, and seeing in
physical laws an escape from his fears, and a solution for his
ambitions, he trained these forces and made them subservient to his
will, and established his right to rule. Out of the maze of the
centuries a steam engine is born--not all at once, for that would be
inconsistent with the law of evolution--but gradually growing first into
practicability, then into efficiency, and finally into perfection, it
stands to-day a beautiful monument of man’s ingenuity, throbbing with
life and energy, and moving the world. What has not the steam engine
done for the Nineteenth Century? It speeds the locomotive across the
continent faster and farther than the birds can fly; no fish can equal
the mighty steamship on the sea; it grinds our grain; it weaves our
cloth; it prints our books; it forges our steel, and in every department
of life it is the ubiquitous, tireless, potent agency of civilization.
Does the ambitious young philosopher predict that electricity will
supersede steam? It is not yet a rational prophecy, for the direct
production of electricity from the combustion of coal is still an
unsolved problem, and behind the electric generator can always be found
the steam engine, modestly and quietly giving its full life’s work to
the dynamo, which it actuates, and caring nothing for the credit,
unmindful of the beautiful and striking manifestations of electricity
which astonish the world, but humbly doing its duty with a silent faith
that the law of correlation of force will always lead the way back to
the steam engine, and place it where it belongs, at the head of all
useful agencies of man.
The Nineteenth Century did not include in its discoveries the invention
of the steam engine. The great gift of James Watt was one of the
legacies which it received from the past, but the economical, efficient,
graceful, and mathematically perfect engine of to-day is the product of
this age.
[Illustration: FIG. 75.--HERO’S ENGINE, 150 B. C.]
The genesis of the steam engine belongs to ancient history, for in the
year 150 B. C. Hero made and exhibited in the Serapeum of Alexandria the
first steam engine. It was of the rotary type and was known as the
“aeolipile.” During the middle ages the spirit of invention seems to
have slept, for nearly eighteen centuries passed from the time of Hero’s
engine before any active revival of interest was manifested in this
field of invention. Giovanni Branca in 1629, the Marquis of Worcester in
1633, Dr. Papin in 1695, Savary in 1698, and Newcomen in 1705, were the
pioneers of Watt, and gave to him a good working basis. Strange as it
may appear, there was in 1894 and probably still is in existence in
England an old Newcomen steam engine (see Fig. 76), which for at least a
hundred years has stood exposed to the weather, slowly rusting and
crumbling away. It is to be found in Fairbottom Valley, half way between
Ashton-under-Lyne and Oldham, and is the property of the trustees of the
late Earl of Stamford and Warrington. It is erected on a solid masonry
pillar 14 by 7 feet at the base, which carries on its top, on trunnions,
an oak beam 20 feet long and 12 by 14 inches thick. This beam is braced
with iron, and has segmental ends with a piston at one end, and a
balance weight at the other. The piston and pump rods are attached by
chains. The cylinder is of cast iron, 27 inches in diameter, and about
six foot stroke, the steam entering at the bottom only. It was formerly
used for pumping a mine.
[Illustration: FIG. 76.--OLD NEWCOMEN ENGINE.]
The distinct and valuable legacy, however, which the Nineteenth Century
received from the past, was the double acting steam engine of James
Watt, disclosed in his British Pat. No. 1,321, of 1782. Prior to this
date steam engines had been almost exclusively confined to raising
water, but with the invention of Watt it extended into all fields of
industrial use. Watt’s double acting engine is shown in Fig. 77. It
comprised a cylinder A, with double acting piston and valve gear E F G
H; the parallel motion R for translating the reciprocating motion of the
piston into the curved oscillatory path of the walking beam; a condenser
chamber K, with spray I, for condensing the exhaust steam; a pump L J to
remove the water from the condenser, and also the air, which is drawn
out of the water by the vacuum; a water supply pump N; the automatic
ball governor D, and throttle valve B. Two pins on the pump rod L strike
the lever H and work the valve gear, and a collecting rod P and crank Q
convert the oscillations of the walking beam into the continuous
rotation of the fly wheel.
[Illustration: FIG. 77.--WATT’S DOUBLE ACTING STEAM ENGINE.]
Watt’s automatic ball governor is shown in Fig. 78 and its function is
as follows: When the working strain on an engine is relieved by the
throwing out of action of a part of the work being performed, the engine
would run too fast, or if more than a normal tax were placed on the
engine, it would “slow up.” To secure a regular and uniform motion in
the performance of his engine Watt invented the automatic or
self-regulating ball governor and throttle valve. A vertical shaft D is
rotated constantly by a band on pulley _d_. Any tendency in the engine
to run too fast throws the balls up by centrifugal action, and this
through toggle links _f h_, pulls down on a lever F G H, and partially
closes the throttle valve Z, reducing the flow of steam to the engine.
When the engine has a tendency to run too slow the balls drop down, and,
deflecting the lever in the opposite direction, open the throttle valve,
and increase the flow of steam to the engine. This double acting engine
of Watt marks the beginning of the great epoch of steam engineering, and
his patent expired just in time to give to the Nineteenth Century the
greatest of all natal gifts.
[Illustration: FIG. 78.--WATT’S AUTOMATIC GOVERNOR AND THROTTLE VALVE.]
Steam engines are divided into two principal classes, the low pressure
engine, using steam usually under 40 pounds to the square inch, and the
high pressure engine, using steam from 50 to 200 pounds. In the low
pressure engine there is the expansive pressure of the steam on one side
of the piston, aided by the suction of a vacuum on the opposite side of
the piston, which vacuum is created by the condensation of the
discharging, or exhaust steam, by cold water. As there are two factors
at work impelling the piston, only a relatively low pressure in the
boiler is required. In the high pressure engines there is no
condensation of the exhaust steam, but it is discharged directly into
the air, and this type was originally called “puffers.” Familiar
examples of the low pressure type are to be found in our side wheel
passenger steamers, and of the high pressure type in the steam
locomotive.
[Illustration: FIG. 79.--PRINCIPLE OF CUT-OFF.]
One of the most important steps in the development of the steam engine
was the addition of the cut-off. Prior to its adoption steam was
admitted to the cylinder during the whole time the piston was making
its stroke from one end of the cylinder to the other. In the cut-off
(see Fig. 79), when steam is being admitted through the port _p_, and
the piston is being driven in the direction of the arrow, it was found
that if the steam were cut off when the piston arrived at the position
1, the expansive action of the steam behind it in chamber _a_ would
continue to carry the piston with an effective force to the end of its
stroke, or to position 2. This of course effected a great saving in
steam. Various cut-offs have been devised. Perhaps that most easily
recognized by most persons is the one seen in the engine room of our
side wheel steamers, of which illustration is given in Fig. 80. This was
invented in 1841 by F. E. Sickels, and was the first successful drop
cut-off. It was covered by his patents, May 20, 1842, July 20, 1843,
October 19, 1844, No. 3,802, and September 19, 1845, No. 4,201. A rock
shaft _s_ is worked by an eccentric rod _e_ from the paddle wheel shaft.
The rock shaft has lifting arms _a_ that act upon and alternately raise
the feet _c_ on rods _b b_. One of these rods _b_ works the valves that
admit steam, and the other the valves that discharge steam. The valve
rod that admits steam has a quick drop, or fall, to cut off the live
steam before the piston reaches the end of its stroke. In Fig. 81 is
shown the celebrated Corliss cut-off and valve gear, in which a central
wrist plate and four radiating rods work the valves. This valve gear was
covered in Corliss patents, No. 6,162, March 10, 1849, and No. 8.253,
July 29, 1851.
[Illustration: FIG. 80.--SICKELS’ DROP CUT-OFF VALVE GEAR.]
[Illustration: FIG. 81.--CORLISS CUT-OFF AND VALVE GEAR.]
Among other important improvements in the steam engine are those for
replenishing the water in the boiler, and the Giffard Injector is the
simplest and most ingenious of all boiler feeds. It was invented in 1858
and covered by French patent No. 21,457, May 8, 1858, and U. S. patent
No. 27,979, April 24, 1860. Prior to the Giffard Injector, steam boilers
were supplied with water usually by steam pumps, which forced the water
into the boiler against the pressure of the steam. The Giffard Injector
takes a jet of steam from the boiler, and causes it to lift the water in
an external pipe, and blow it directly into the boiler against its own
pressure. So paradoxical and inoperative did this seem at first that it
was met with incredulity, and not until repeated demonstrations
established the fact was it accepted as an operative device. Its
construction is shown in Fig. 82. A is a steam pipe communicating with
the boiler, B another pipe receiving steam from A through small holes
and terminating in a cone. C is a screw rod, cone-shaped at its
extremity, turned by the crank M, and serving to regulate and even
intercept the passage of steam. D is a water suction pipe. The water
that is drawn up introduces itself around the steam pipe and tends to
make its exit through the annular space at the conical extremity of the
latter steam pipe. This annular space is increased at will by means of
the lever L, which acts upon a screw whose office is to cause the pipe B
and its attached parts to move backward or forward. E is a diverging
tube which receives the water injected by the jet of steam that
condenses at I, and imparts to the water a portion of its speed in
proportion to the pressure of the boiler. F is a box carrying a check
valve to keep the water from issuing from the boiler when the apparatus
is not at work. G is a pipe that leads the injected water to the boiler.
H is a purge or overflow pipe, K a sight hole which permits the
operation of the apparatus to be watched, the stream of water being
distinctly seen in the free interval. Fig. 83 shows the application of
the injector to locomotives, which are now almost universally supplied
with this device.
[Illustration: FIG. 82.--GIFFARD INJECTOR.]
[Illustration: FIG. 83.--INJECTOR ON LOCOMOTIVE.]
To keep the pressure in the boiler within the limit of safety, and
adjusted to the work being performed, is an important part of the
engineer’s duty, and this he could not do without the steam gauge. One
of the best known is the Bourdon gauge, shown in Fig. 84, constructed on
the principle of the barometer invented by Bourdon of Paris in 1849 and
patented in France June, 1849, and in the United States August 3, 1852,
No. 9,163. A screw threaded thimble B, with stop cock A, is screwed in
the shell of the boiler, and a coiled pipe C communicates at one end
with the thimble and is closed at the other end E and connected by a
link F, with an arm on an axle, carrying an index hand that moves over a
graduated scale. The coiled pipe C is in the nature of a flattened
tube, as shown in the enlarged cross section, and is enclosed in a case.
When the steam pressure varies in this flat tube its coil expands or
contracts, and in moving the index hand over the scale indicates the
degree of pressure.
[Illustration: FIG. 84.--BOURDON’S PRESSURE GAUGE.]
In line with the development of the steam engine must be considered the
efforts to economize fuel. These may be divided into the following
classes: Increased steam generating surface in boiler construction;
surface condensers for exhaust steam; devices for promoting the
combustion of fuel and burning the smoke, and feed water heaters. Even
before the Nineteenth Century Smeaton devised the cylindrical boiler
traversed by a flue, but the multitubular steam boiler of to-day
represents a very important Nineteenth Century adjunct to the steam
engine. Our locomotives, fire engines, and torpedo boat engines would be
of no value without it. Sectional steam boilers made in detachable
portions fastened together by packed or screw joints also represent an
important development. These permit of the removal and replacement of
any one section that may become defective, and are also capable of being
built up section by section to any size needed. For promoting the
combustion of fuel the draft is energized by blasts of air or steam, or
both, either through hollow grate bars, jet pipes in the fire box, or by
discharging the exhaust steam in the smoke pipe. Surface condensers pass
the exhaust steam over the great surface area of a multitubular
construction having cold water flowing through it. Feed water heaters
utilize the waste heat escaping in the smoke flue to heat the water that
is being fed to the boiler, so that it is warm when it is injected into
the boiler, and the furnace is relieved of that much work.
[Illustration: FIG. 85.--BRANCA’S STEAM TURBINE, 1629.]
[Illustration: FIG. 86.--SECTION OF PARSONS TURBINE OF 1891.]
In the reciprocating type of steam engine the inertia of the piston must
be overcome at the beginning of each stroke and its momentum must be
arrested at the end of each stroke, and this involves a great loss of
power. If the power of the steam could be applied so as to continuously
move the piston in the same direction this loss would be avoided. The
effort to do this has engaged the attention of many inventors, and the
devices are called rotary engines. The most successful engines of this
kind are those of the impact type, in which jets of steam impinge upon
buckets after the manner of water on a water wheel, and which are known
to-day as steam turbines. The earliest of these is Branca’s steam
turbine of 1629 (see Fig. 85) and the most important of this class in
use to-day are those of Mr. Parsons, of England, and De Laval, of
Sweden. The internal construction of the Parsons turbine is seen in Fig.
86 and is covered by British patent No. 10,940, of 1891, and United
States patent No. 553,658, January 28th, 1896. A series of turbines are
set one after the other on the same axis, so that each takes steam from
the preceding one, and passes it on to the next. Each consists of a ring
of fixed steam guides on the casing, and a ring of moving blades on the
shaft. The steam passes through the first set of guides, then through
the first set of moving blades, then through the second set of guides,
and then through the second set of moving blades, and so on.
[Illustration: FIG. 87.--PARSONS COMPOUND STEAM TURBINE, ON PLURALITY OF
PROPELLER SHAFTS.]
In the application of his turbine to marine propulsion Mr. Parsons
employs a plurality of propeller shafts and steam turbines, as seen in
Fig. 87, and covered under United States patent No. 608,969, August 9,
1898.
[Illustration: FIG. 88.--DE LAVAL’S STEAM TURBINE.]
[Illustration: FIG. 89.--DE LAVAL TURBINE GEARED TO DYNAMO.]
The De Laval turbine, as shown in Fig. 88, is of very simple
construction, consisting only of a steel wheel with a series of buckets
at its periphery enclosed by a circular rim, and a series of steam
nozzles on the side with diverging jet orifices directing steam jets
against the buckets. A speed of 30,000 revolutions a minute may be
attained by this construction. In Fig. 89 is shown a 300 horse-power
steam turbine of the De Laval type applied to a dynamo; to which this
type of engine is peculiarly adapted. The dynamo is seen on the extreme
right, the steam turbine on the extreme left, and the drum-shaped
casing between contains cog-gearing by which the high revolution of the
turbine wheel is reduced to a proper working speed for the dynamo.
Within the last few years application of the Parsons steam turbine has
been made to marine propulsion with very remarkable results as to speed.
The small steam craft, “The Turbinia,” built in 1897, and supplied with
three of Parsons’ compound steam turbines, developed a speed of 32¾
knots, and more recently the torpedo boat “Viper” has with steam
turbines attained the remarkable speed of 37.1 knots, or over 40 statute
miles an hour. About 2,000 United States patents have been granted on
various forms of rotary engines.
In the transportation building of the World’s Fair at Chicago in 1893
one of the most conspicuous objects of attention was the model of the
great Bethlehem Iron Co.’s steam hammer, standing with its feet apart
like some great “Colossus of Rhodes” and towering 91 feet high among the
models of the great ocean steamers and battleships which are so largely
dependent upon the work of this Titanic machine. Its hammer head, in the
working-machine, weighs 125 tons, and many of the seventeen inch thick
armor plates for our battleships have been forged by its tremendous
blows.
In 1838, during the construction of the “Great Britain,” the largest
steamship up to that time ever built, it was found that there was not a
forge hammer in England or Scotland powerful enough to forge a paddle
shaft for that vessel. The emergency was met by Mr. Nasmyth, of England,
who invented the steam hammer and covered it in British patent No.
9,382, of 1842 (U. S. Pat. No. 3,042, April 10, 1843). A modern example
of it is seen in Fig. 90. It consists of a steam cylinder at the top
whose piston is attached to a block of iron, forming the hammer head and
sliding vertically in guides between the two legs of the frame. Valve
gear is arranged to control the flow of steam to and from the opposite
sides of the piston, and so nicely adjusted is the valve gear of such a
modern steam hammer that it is said that an expert workman can
manipulate the great mass of metal with such accuracy and delicacy as to
crack an egg in a wineglass without touching the glass. To the steam
hammer we owe the first heavy armor plate for our battle ships and the
propeller shafts of our earlier steamships. In fact it was the steam
hammer which first rendered the large steamship possible. Mr. Nasmyth
not only invented the steam hammer, but the steam pile driver as well.
[Illustration: FIG. 90.--STEAM HAMMER.]
For quick action, nicely adjusted machinery, and showy finish the steam
fire engine is a familiar and conspicuous application of steam power. A
dude among engines when on dress parade, and a sprinter when on the run,
it gets to work with the vim and efficiency of a thoroughbred, and is a
most business-like and valuable custodian of life and property. The
first portable steam fire engine was built about 1830 by Mr. Brathwaite
and Capt. Ericsson in London. In 1841 Mr. Hodges produced a similar
engine in New York City. Cincinnati was the first city to adopt the
steamer as a part of its fire department apparatus. To-day all the
important cities and towns of the civilized world rely upon the steam
fire engines for their longevity and existence. Time economy in getting
into action is the great objective point of most improvements of the
fire-engine, and one of the most important is the keeping of the water
in the boiler hot when the engine is out of action at the engine house,
so that when the fire is built and the run is made to the scene of
action, the water will be hot to start with. This attachment was the
invention of William A. Brickill, and was patented by him August 18,
1868, No. 81,132. In the illustration, Fig. 91, the two pipes passing
from the engine through the trap door in the floor connect with a water
heater in the basement below, which heater maintains a constant
circulation of hot water in the steam boiler. Couplings in these pipes
serve to quickly disconnect the engine when the run to the fire is to be
made.
[Illustration: FIG. 91.--STEAM FIRE ENGINE WITH WATER HEATING
ATTACHMENT.]
Among other useful applications of the steam engine are the steam plow,
steam drill, steam dredge, steam press, and steam pump, of which latter
the Blake, Knowles, and Worthington are representative types.
[Illustration: FIG. 92.--THE SIX-CYLINDER QUADRUPLE EXPANSION ENGINES OF
THE “DEUTSCHLAND,” 35,640 HORSE POWER.]
The highest type of modern steam engines is to be found in the compound
multiple-expansion engine, in which three or more cylinders of different
diameters with corresponding pistons are so arranged that steam is made
to act first upon the piston in the smallest cylinder at high pressure,
and then discharging into the next larger cylinder, called the
intermediate, acts expansively upon its piston, and thence, passing into
the still larger low pressure cylinder, imparts its further expansive
effect upon its piston. The fundamental principle of the compound engine
dates back to the time of Watt, its first embodiment appearing in the
Hornblower compound engine, as described in British patent No. 1,298, of
1781, but modern improvements have differentiated it into almost a new
invention. A fine example is shown in Fig. 92, which represents the
quadruple expansion engines of the “Deutschland,” the new steamer of the
Hamburg-American Line. The two high pressure cylinders, however, do not
appear in the illustration, being too high for the shops. They stand
vertically, however, upon the two bed plates which appear at the top of
the two low pressure cylinders. In each set of six cylinders the two low
pressure cylinders are in the middle, the two high pressure cylinders
immediately above them or arranged tandem, while at the forward end is
the first intermediate cylinder, and at the after end is the second
intermediate. The low pressure cylinders are 106 inches in diameter, the
intermediate cylinders are 73.6 inches and 103.9 inches respectively,
and the two high pressure cylinders are 30.6 inches, and the steam
pressure is 225 pounds. Its improvements comprehend the systems of
Schlick, patented in the United States November 23, 1897, No. 594,288
and 594,289, and Taylor, patented November 22, 1898, No. 614,674, which
embody fine mathematical principles for balancing the momentum of the
great masses of moving parts, so that the engine may run up to high
speed without vibrations and damaging strains upon the hull.
Mulhall gives the steam horse power of the world in 1895, not including
war vessels, as follows:
Stationary. Railway. Steamboat. Total.
The World 11,340,000 32,235,000 12,005,000 55,580,000
United States 3,940,000 10,800,000 2,200,000 16,940,000
The increase in steam power in the United States has been from 3,500,000
horse power in 1860, to 16,940,000 horse power in 1895, or about five
fold within thirty-five years.
Prof. Thurston says that in 1890 the combined power of all the steam
engines of the world was not far from 100,000,000[2] horse power, of
which the United States had 15,000,000, Great Britain the same, and the
other countries smaller amounts. Taking the horse power as the
equivalent of the work of five men, the work of steam is equivalent to
that of a population of 500,000,000 working men. It is also said that
one man to-day, with the aid of a steam engine, performs the work of 120
men in the last century.
[2] Prof. Thurston’s estimate doubtless includes war vessels, which
Mulhall’s later estimate does not (see Mulhall’s “Industries and
Wealth of Nations,” 1896, pages 4 and 379).
The influence of the steam engine upon the history and destiny of the
world is an impressive subject, far beyond any intelligent computation
or estimate. It has been the greatest moving force of the Nineteenth
Century. The labor of 100,000 men for twenty years might build a great
pyramid in Egypt, and it remains as a monument of patience only, but the
genius of the modern inventor has organized a machine with muscles of
steel, far more patient and tireless than those of the Egyptian slave.
He gave it but a drink of water and making coal its black slave, and
himself the master of both, he has in the Nineteenth Century hitched his
chariot to a star and driven to unparalleled achievement.