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LIFE OF RICHARD TREVITHICK,
With an Account of His Inventions.
by
FRANCIS TREVITHICK, C.E.
Illustrated with Engravings on Wood by W. J. Welch.
VOLUME II.
London:
E. & F. N. Spon, 48, Charing Cross.
New York:
446, Broome Street.
1872.
London: Printed by William Clowes and Sons, Duke Street,
Stamford Street and Charing Cross.
CONTENTS OF VOLUME II.
CHAPTER XVII.
VARIOUS INVENTIONS.
Stone-crushing mill, 1804--Portable puffer, 1805--Staffordshire
potteries--Engine for South America--Diversity of steam
appliance--Numerous high-pressure engines--West India Dock
locomotive--Engines at Newcastle--Blacklead lubricator--Engines in
Wales--Mine engines on wheels, 1804--Engines in London--Engines to be
sold in market towns--Blast-furnaces--Aërated steam-boiler--St. Ives
Breakwater--Dolcoath blast copper furnace--Davies Gilbert's opinion of
the aërated steam-boiler--Trevithick's advice to a brewer--Agricultural
engines--West India engines--Thrashing engine--Horizontal
engines--Expansive steam--Cold surface condenser--Air-pump--Expansive
cam--Fire-bars--Comparison with Watt's engine--Stone-boring engine,
1813--Plymouth Breakwater, reduction in cost--Locomotive engine,
1813--Stone splitting--New method of stone boring, 1813--Screw bit,
1813--Falmouth Harbour--Exeter Bridge--Engine at Lima--Proposed train
from Buenos Ayres to Lima--West India portable engine Page 1-35
CHAPTER XVIII.
AGRICULTURAL ENGINES; LOSS OF PAPERS.
Sir Christopher Hawkins's thrashing machine, 1812--Report of three
wise men--Cost of horse and steam power--Wheal Liberty engine--Sir
John Sinclair and the Board of Agriculture--Cost of engine--Power of
engine--Welsh locomotive--Trevithick on steam agriculture--West Indies
engine--Horse-power--Trevithick on patents--Engines in charge of
labourers--Teapot--Detail of agricultural engine--Lord Dedunstanville's
thrashing machine--Plymouth Breakwater locomotive--Wheal Prosper
engine--Wheal Alfred engine--Steam-plough--Cultivation of
commons--Combined steam-tormentor, narrower, and shoveller--Mr.
Rendal's thrashing machine--Cost and work performed by thrashing
engines--Their durability--Bridgenorth engine--Trevithick's drawings
light the tires 36-68
CHAPTER XIX.
POLE STEAM-ENGINE.
Return to Cornwall, 1810--Wheal Prosper pole vacuum engine,
1811--Cylindrical boilers, 1811--Steam pressure, 100 lbs.--Duty
of engine, 40 millions--Expansive working, 1811--Herland
high-pressure pole puffer, 1815--Steam pressure, 150 lbs.--Boiler
making--Comparison with Watt's engine--Blue-fire--Steam--Patent
specification--Steam-ring stuffing box--Engines in Lima--A 33-inch
pole-puffer more powerful than a 72-inch Watt engine--Description
of pole engine and boilers--Trevithick's calculation--Trial of
Herland engines--Steam-cushion--Power of the pole-engine--Defective
workmanship--Sims examines the pole-engine--Opposition from
shareholders--Defective boilers--Challenge to Woolf--Davies
Giddy's opinion--First cost, and cost of working one-third of
the Watt engine--Meeting of opposing shareholders--Duty of the
high-pressure steam pole puffer-engine, 1816--Comparison with the Watt
engine--Combined high-pressure pole and cylinder for expansion--Wheal
Alfred Watt engine converted to high pressure--Wheal Chance combined
engine--Mr. Michael Williams's opinion--Woolf and Trevithick Page 69-113
CHAPTER XX.
THE WATT AND THE TREVITHICK ENGINES AT DOLCOATH.
Early steam-engines--Semicircular boiler, 1775, net power 7 lbs.
on the inch--Watt's statement in 1777--Engines in Dolcoath--Watt's
engine, 1778--Watt's engine at Herland, 1798--Trevithick's tubular
boiler, 1799--Reconstruction of the Carloose 45-inch, 1799--Gross and
net power of engines--Comparison of Newcomen, Watt, and Trevithick
engines--Boiler explosion, 1803--Strong rivalry with Watt--Locomotive
at Coalbrookdale, 1803--Watt's proposed locomotive--Competition in
Wales--Numerous high-pressure engines, 1803--Patent difficulty--Watt's
opposition, 1804--Government inquiry--Competitive trials in
Wales--Tramway locomotive, 1804--The bet--Opposition because of saving
of labour--Worcester engine--West India Docks engine--High-pressure
steam condensing engines--One or two cylinders for expansion--Sirhowey
boilers--Mr. Homfray's opinion of the Watt opposition--Mr.
Whitehead makes engines in Manchester--Cylindrical tubular boiler
in Wales for large engines, 1805--Watt contests at Dolcoath,
1805--Steam-blast--Superiority of high-pressure whim-engines--Proposed
boiler for the large pumping engine, 1806--Steam pressure--The Watt
boiler--Comparison of size of fire-place and coal used--Dredger
contract--Theory of steam--Trevithick's Dolcoath boiler when
applied to the Watt engine, with expansive gear, to save 300l.
monthly, 1806--Momentum of pumping engine--Continued tests of high
and low pressure whim-engines at Dolcoath--Watt engine put aside,
1806--High-pressure engines ordered, 1806--High-pressure pumping
engine for Wheal Abraham, 1806--Disputed patent right--Expansion
reduces heat--Boiler for the Watt 63-inch engine, 1806--Cost of
Trevithick's boiler--Advantage of small tubes in boilers--Trinity
Board--Watt's steam-cylinder unsuitable for high steam, 1806--Sims'
trial of engines--Little fight--Tubular boilers, 1806--High-pressure
steam pumping engines, 1818--Reporter of engines--Application to
Government, 1810--Dolcoath engines and boilers--High steam to the Watt
engine--Duty of engines, 1812--Watt's boiler thrown out--Expansive
valve--Dolcoath manager--Saving by boilers and expansive working,
1812--Lean's reports--Increased duty of the three old Dolcoath
engines, 1814--76-inch engine, 1816--80,000l. a year saved--Durability
of engine--Its removal--Cylindrical boilers--Hornblower and Watt
engines--Davies Gilbert's report, 1798--Lean's report, 1816--Watt's
views of expansive working--Watt's steam of 1 or 2 lbs. to the
inch--Pole's statement--Engine at Marazion, 1804--Woolf in
Cornwall--Rees' Cyclopædia--'Encyclopædia Britannica'--Application to
Parliament--Wheal Towan--Newcomen and Watt engines--Pompe-à-feu 'La
Belle Machine,' Dolcoath Page 114-194
CHAPTER XXI.
ENGINES FOR SOUTH AMERICA.
Engines for Lima, 1813--Uville's application to Watt--High-pressure
model--Cerro de Pasco mines--Uville's return in search of
Trevithick--Engines ordered--Pump-work--Modern pumping engines--Money
difficulty--Weight of pieces--'Sanspareil' of 1813--Expansive
working--Quartz crusher--Locomotive for South America, 1813--Sketch
of winding engine--Their simplicity of form--Power and cost of
engines--Trevarthen and Bull to accompany the engines--A third
man recommended--Boilers put together at Cerro de Pasco--Uville's
arrest--Trevithick a shareholder--Vivian's application--Departure of
machinery, 1814--Uville's agreement--Invoice of engines sent
Page 195-220
CHAPTER XXII.
PERU.
Agreement for working the Peruvian mines, 1812--Uville and
Watt, 1811--Uville and Trevithick, 1813--Uville's opinion of
Trevithick--Estimated value of the mines--Machinery reached Peru,
1815--Trevithick's departure from Penzance, 1816--Mr. Edmond's
statement--Cerro de Pasco mines in 1850--Report from the Viceroy of
Peru, 1816--Report from the Magisterial Deputation of Yauricocha,
1816--Despatch from the Governor of the Province of Tarma,
1816--Pumping engines at work--The Viceroy's reply--Report in the
'Lima Gazette,' 1816--Trevithick's reception at Lima--Trevithick's
report, 1817--Differences between Trevithick and Uville--Trevithick's
thoughtless acts--His visit to the nunnery--The Lord Warden proposed
to erect a statue in silver to Trevithick--Bust of Trevithick
in Cornwall--Quicksilver--Sunk ship--Chili--Copper and silver
mine--Departure from Lima--Cerro de Pasco mines Page 221-259
CHAPTER XXIII.
COSTA RICA.
Gerard at Punta de Arenas, in the Pacific, in 1822--Nicolas
Castro worked a gold mine, 1821--Alverado's ore-grinding machine,
1822--Climate of Costa Rica--Mines in the Cordillera--Canal
from the river Machuca to Quebrada-honda--Castro's mine--Padre
Arias, or the Priest's mine--Trevithick and Gerard's proposal
for iron railroads, &c., for the mines of Costa Rica, 1827--New
line of road from San Juan, on the Atlantic, to the Costa Rica
mines--Serapique River navigable--Trevithick's diary--A mule track
easily constructed--Comparative distance to the mines from the
head of the Serapique on the Atlantic, and Punta de Arenas on the
Pacific--Trevithick nearly drowned in the Serapique--Nearly starved
before reaching San Juan--Performs a surgical operation--Designed
the locomotive between breakfast and dinner--Robert Stephenson and
Trevithick at Carthagena--Nearly drowned in the Magdalena--Saved by Mr.
Bruce Napier Hall--Trevithick nursed Robert Stephenson Page 260-275
CHAPTER XXIV.
RETURN TO ENGLAND.
Bodmin School, 1827--Cube root--Trevithick's reception--Saving in
Cornish mines--Model gun--Gerard's return, 1827--His meeting Robert
Stephenson--His remarks on Costa Rica--Montelegre's search for a better
line of road--Mr. M. Williams's proposal--Change of Ministry, and the
gun-carriage--Model of iron packet-ship and engine--Robert Stephenson's
remarks on mining--Trevithick's rejection of purchase-money
Page 276-283
CHAPTER XXV.
GUN-CARRIAGE--IRON SHIPS--HYDRAULIC CRANE--ICE MAKING--DRAINAGE
OF HOLLAND--CHAIN-PUMP--OPEN-TOP CYLINDER--HAYLE HARBOUR--PATENT
RIGHTS--PETITION TO PARLIAMENT.
Trevithick's description of gun-carriage and iron ship--Select
committee--Glasgow iron-ship builders--Trevithick's comparison of
gunpowder and steam--Cranes worked by air or water--Artificial
cold--Liberality--Holland--Drainage--Dredging--Zuyder
Zee--Hydraulic crane--Dutch pumping engine--Chain-pump--Haarlem
Lake--Rhine--Windmills--Hayle Harbour--Disputed pole-engine
patent right--Petition to Parliament, 1828--Marine boilers--Steam
pressure--Engine duty--Lords of the Treasury refuse the
petition--Davies Gilbert's views--Marine compound engine of 1871
Page 284-314
CHAPTER XXVI.
TUBULAR BOILER--SUPERHEATING STEAM--SURFACE CONDENSER.
Binner Downs engine, 1828--Fires around cylinder and
steam-pipes--Saving of coal--Surface condensation at sea--Superheating
tubes--Used steam returned to the boiler, 1828--Holland pumping
engine--Woolf at the Consolidated Mines--Laws of steam--Power
of heat from 1 lb. of coal--Loss of heat--Experiments at Binner
Downs--Surface condensation--Partial surface condensation for ships
or railways--Effect of superheating--Watt's theory doubted--Wheal
Towan and other engines--Loss of heat--Injection-water--Surface
condensation and superheating--Partial condensation engine--Duty
of chain pumping engine--Surface condensation by cold water or
air--Results of the experiment--Hayle Harbour--Condenser of copper
tubes, 1829--Suitability for steam-ships--Proposal to erect at his own
expense a marine engine with surface condenser and screw-propeller
for the instruction of the Admiralty, 1830.--Sketch of tubular boiler
and surface-air condenser--Screw draught--Preservation of heat in
condensing by air--Comptroller of the Navy--Patent of 1831--Boiler
within the condenser--Surface condensation by air or water--Safety
boiler of concentric tubes--Blowing vessel for air condensation
and draught--Tubes for distilling water--Steam pressure--Expansive
working--Robert Stephenson's statement--'Echo' steamboat,
1831--Bottle-neck boiler--Admiralty--Steam Users' Association--Mr.
Alexander Crichton's boiler and surface condenser--Captain Dick and
Captain Andrew--Captain King and the 'Echo' Page 315-362
CHAPTER XXVII.
HEATING APPARATUS--MARINE STEAM-ENGINES--REFORM COLUMN.
Ill health, 1830--Hot-house boiler--Heating rooms--Discharging
coal-ships by steam--Hot-water stoves for France--Patent for heating
apparatus, 1831--Marine portable engines--Boat propeller--Wheal
Towan--Discharging coal by steam at Hayle--Proposal to the Common
Council of London--Every vessel to carry a steam-engine--Mr. George
Rennie--Proposal to the Admiralty--Surface condensation--Locomotives
supplying their own feed-water--Petition in Trevithick's
favour--Davies Gilbert's suggestion--His comparison of the Watt
and Trevithick engines--Maudslay on Trevithick's proposals--Patent
of 1832--Superheating steam--Cylinder placed in flue from
boiler--Expansive steam--Tubular boiler--Water propulsion--Superheating
and surface condensation for locomotives--Detail of engine--Proposal
to send steamboats to Buenos Ayres--Waterwitch Company--Messrs.
Hall and Sons--Hall's condenser--Rennie and the Admiralty--'Syria'
steamboat--Compound engines--Watt on high-pressure steam--Trevithick
on compound engines--Tubular boiler and variable blast-pipe--Refusal
of Trevithick's petition to Government--Ill health--Davies
Gilbert's statement to Spring Rice--Meeting on proposed Reform
Column--Trevithick's description--Means of ascent and descent--Placed
before the King--Death--Funeral--His last letter Page 363-396
ILLUSTRATIONS TO VOLUME II.
PAGE
AËRATED STEAM-BOILER 7
ROCK SPLITTING 25
STEAM THRASHING ENGINE 37
AGRICULTURAL MACHINE 58
WHEAL PROSPER HIGH-PRESSURE STEAM POLE-ENGINE 70
CYLINDRICAL HIGH-PRESSURE STEAM-BOILERS 71
EXPANSIVE STEAM POLE-ENGINE 81
CARN BREA CASTLE 147
TREVITHICK'S DOLCOATH ENGINE OF 1816 168
TREVITHICK'S DOLCOATH BOILERS OF 1811 169
STEAM DIAGRAM 185
'LA BELLE MACHINE' 190
CARRIAGE-WHEELS 207
WINDING ENGINES 208
PENZANCE IN OLDEN TIME 228
MARKET, JEW STREET, PENZANCE 243
MULE TRACK FROM LIMA TO CERRO DE PASCO 258
MAP OF COSTA RICA MINES 260
GUN-CARRIAGE 285
DUTCH PUMPING ENGINE 298
MOUNT'S BAY 318
PARTIAL CONDENSATION ENGINE 332
TUBULAR BOILER AND CONDENSER 339
BOTTLE-NECK BOILER 357
CAPTAIN DICK AND CAPTAIN ANDREW 361
HOT-WATER ROOM-WARMER 364
PATENT HEATING APPARATUS 366
DUCK'S-FOOT PADDLE 369
MARINE ENGINE AND BOILER 380
COMPOUND MARINE ENGINE 385
REFORM COLUMN IN DETAIL 391
GENERAL VIEW OF REFORM COLUMN 393
LIFE OF TREVITHICK.
CHAPTER XVII.
VARIOUS INVENTIONS.
"About 1804 Captain Trevithick put up in Dolcoath Mine a
stone-crushing mill, having large cast-iron rollers, for breaking into
small pieces the large stones of ore; it was spoken of as the first
ever used for such a purpose; the same form of crusher is still used
in the mines. It caused a great saving compared with breaking by a
hand hammer."[1]
"I saw at the Weith Mine in 1805 a portable high-pressure engine, made
by Captain Trevithick.
"It was called a puffer; the cylinder was in the boiler; the steam
about 30 lbs. on the inch above the atmosphere. A wooden shed
sheltered the engine and man.
"The facility of manufacture and cheapness of those engines caused
them to be much used in the mines, and also elsewhere."[2]
[Footnote 1: Recollections of the late Captain Charles Thomas, manager
of Dolcoath.]
[Footnote 2: Captain Samuel Grose's recollections.]
Mrs. Trevithick, about the time we are speaking of, accompanied
her husband through one of the Staffordshire china manufactories.
Trevithick said to the manufacturer, "You would grind your clay much
better by using my cast-iron rolls and high-pressure steam-engine." The
manufacturer begged him to accept a set of china. Mrs. Trevithick was
disappointed at hearing her husband say "No! I have only told you what
was passing in my mind."
Driving rolling-mills was among the early applications of the
high-pressure steam-engines; but pulverizing hard rock by the use
of iron rollers was a novelty: though his patent of 1802 shows the
proposed rolls driven by steam for crushing sugar-canes, yet no one had
dreamt, prior to 1804, of economy in crushing stone and clay by such a
means. The plan, however, remains in use to this day in many mines, and
is frequently spoken of under the name of quartz-crusher.
"MR. GIDDY, COALBROOKDALE, _September 23rd, 1804_.
"Sir,--Yours of the 13th this day came to hand. I left Wales about
eight weeks since, and put an engine to work in Worcester, of 10-horse
power, for driving a pair of grist-stones, and a leather-dressing
machine, and another in Staffordshire for winding coals; each of them
works exceedingly well.
"From Coalbrookdale I went to Liverpool, where a founder had made two
of them, which also worked exceedingly well; one other was nearly
finished, and three others begun. Some Spanish merchants there saw one
of them at work, and said that as soon as they returned to Spain they
would send an order for twelve engines, of 12-horse power, for South
America. In South America and the Spanish West Indies water is very
scarce; in several places there is scarcely water for the inhabitants
to drink, therefore there is no water for any engine. By making
inquiry, I found that ten mules would roll as much cane in an hour as
would produce 250 gallons of cane-juice, which they boil until the
water is evaporated, and the sugar produced.
"I told them that the engine-boiler might be fed with this juice,
and by a cock in the bottom of the boiler constantly turning, and by
taking a greater or smaller stream from it, they might make the juice
as rich as they liked. In this process the juice would be so far on
towards sugar, and the fire that worked the engine would cost nothing,
because it would have taken the same quantity of fuel under the
sugar-pans to evaporate the water, as it would in the engine-boiler.
"The steam from the engine might be turned around the outside of the
furnace for distilling rum, as the distilleries require but a slow
heat.
"I think the steam would answer a good purpose around the outside of
the pan.
"If this method answers, the cost of working the engine would be
nothing, and the engine would be then working, as it were, without
fire or water.
"The Spaniards told me that if this plan answers, they would take a
thousand engines for South America and the Spanish West Indies. I
shall be very much obliged to you for your opinion on this business.
These merchants make a trade of buying up sugar mills and pans, with
every other thing they want from England, and exchange them with the
Spaniards for sugar.
"At Manchester I found two engines had been made and put to work;
they worked very well: three more are in building. From there I went
to Derbyshire. The great pressure-engine I expect will be at work
before the middle of October. A foundry at Chesterfield is building a
steam-engine as a sample; two foundries in Manchester are at full work
on them, and one in Liverpool. There are six engines nearly finished
at Coalbrookdale, and seven in a foundry at Bridgenorth.
"I am making drawings for several other foundries. Any number of them
would sell. A vast number are now being erected, and no other engine
is erected where these are known. The engine for the West India Docks
was neglected during my absence from the Dale, but I expect it will be
ready to send off in ten days.
"In about three weeks I shall be in London to set it up. It will
please you very much, for it is a very neat and complete job, and I
have no doubt will answer every purpose exceedingly well. At Newcastle
I found four engines at work, and four more nearly ready; six of these
were for winding coal, one for lifting water, and one for grinding
corn.
"That grinding corn was an 11-inch cylinder, driving two pair of
5-feet stones 120 rounds per minute; ground 150 winchesters of wheat
in twelve hours with 12 cwt. of small coal. It worked exceedingly
well, and was a very complete engine, only the stroke was much too
short, not more than 2 feet 6 inches, which made very much against the
duty.
"The other engine that was lifting water had a 5-1/2-inch diameter
cylinder, with a 3-feet stroke, drawing 100-gallon barrels,
twenty-four every hour, 80 yards, burning 5 cwt. of coal in
twenty-four hours.
"This work it did with very great ease. I believe you will find this
an exceeding good duty for a 5-1/2-inch cylinder engine.
"Below I send a copy of Mr. Homfray's and Mr. Wood's letters to me:--
"Mr. Homfray's, of the 10th September.--'Our great engine goes on
extremely well here, nothing can go better; the piston gives no
trouble; it goes about three weeks, and we work it with blacklead and
water; the cylinder is as bright as a looking-glass; it uses about 2
lbs. of blacklead in a week; about once in twelve or fifteen hours we
put a small quantity of blacklead, mixed with a little water, through
the hole in the cylinder screw, and we never use any grease. We rolled
last week 140 tons of iron with it, and it will roll as fast with the
both pair of rolls, as they can bring to it.'
"Mr. Wood's letter, September 12th.--'We are going on, as it is likely
we always shall, in the old dog-trot way, puddling and rolling from
the beginning of the week till the end of it. Your engine is the
favourite engine with every man about the place, and Mr. Homfray says
it is the best in the kingdom.'
"I have not the smallest doubt but that I can make a piston without
any friction or any packing whatever, that needs not to have the
cylinder screw taken up once in seven years. It is a very simple plan,
and will be perfectly tight; it is by restoring an equilibrium on both
sides of the piston. I expect to see you in London soon, and then will
give you the plan for inspection before I put it in practice.
"I am very much obliged to you for recommending these engines in
Cornwall, but you have not stated in what manner they are to be
applied; whether to work pumps, or barrels, or both. They may be made
both winding and pumping engines at the same time, if so required.
"A rotative engine will cost more than an up-and-down-stroke, on
account of the expense of the fly-wheel and axle. An engine capable
of lifting 180 gallons of water per minute 20 fathoms would cost,
when complete and at work, patent right included, about 220_l._ If
it is a rotative engine, with a winding barrel, it will cost 270_l._
I expect that a 7-inch cylinder would be sufficient for winding at
Penberthy Crofts, which might have a Crank on the fly for lifting
water in pumps, and a winding barrel on its back. This would cost
about 170_l._; the erection of them, when on the spot, will cost
nothing. You do not say when you intend to be in town. I hope you will
be present when the dock-engine is set to work.
"The engines first sent to Cornwall, must be from Coalbrookdale; then
they will be well executed, but from Wales it would not be so.
"You may depend on having a real good engine sent down, with
sufficient openings given to the passages.
"The engineer from the Dale has been lately in London, and has just
returned; he gives a wonderful account of the engines working in
London. There are twelve now at work there. They have well established
their utility in different parts of the kingdom, and any number would
sell. The founders intend to make a great number, of different sizes,
and send them to different markets for sale, completely finished, as
they stand.
"You do not say anything about wheels to the engine for Penberthy
Crofts. There are several engines here nearly finished; if they suit
in size for Penberthy, one may be sent down in four or five weeks,
otherwise it may be two months.
"I am, Sir,
"Your very humble servant,
"RICHARD TREVITHICK.
"Direct for me at the Talbot Inn, Coalbrookdale."
Trevithick worked hard and successfully in making his steam-engines
useful, and firmly believed that he could and would make them universal
labourers. Even the Spanish merchants, unacquainted with steam,
talked of giving an order for several engines for South America; and
their glowing account of the wide field open to him may have been
instrumental to his going to that country by making his engines
known there. His proposal to make the sugar-cane convert itself into
sugar by the use of his patent high-pressure steam-engine may be more
theoretical than practical; but many more unlikely things have come to
pass.
At that time several of his engines were at work in Wales, Worcester,
Staffordshire, Coalbrookdale, Manchester, Derbyshire, Liverpool,
Cornwall, and Newcastle-upon-Tyne. Twelve were at work in London, and
so familiar were people with them, that founders intended to construct
them of different sizes, and send them for sale at the large market or
county towns; their cost complete, ready for work, to be 200_l._, more
or less, according to size, with a range of application unlimited. His
one letter, casually written sixty-seven years ago, mentions them as
grinding corn, dressing leather, winding coal, crushing sugar-cane,
prepared to boil sugar, and distil rum; pumping water, rolling iron,
railway locomotion, portable steam fire-engine, portable steam-crane,
mine engines on wheels; so that it may almost be said he was not too
sanguine in hoping to send in 1804 a thousand of his engines to South
America, for in those cursory remarks he draws attention to no less
than thirty-six high-pressure steam-puffers at work.
The Penberthy Croft Mine portable engine could be placed on wheels or
otherwise, according to the wish of the purchaser, as though steam
locomotion was an every day occurrence in 1804.
"CAMBORNE, _January 13th, 1811_.
"MR. GIDDY,
"Sir,--From calculating the quantity of blast given to a
blast-furnace, I find a considerable quantity more of coal consumed by
the same quantity of air in this way, than by the usual way in common
engine chimneys. Of course the more cold air admitted to pass through
the fire, the more heat carried to the top of the stack. Crenver
63-inch cylinder, double-power, 8-feet stroke, with but one boiler,
works five strokes per minute. This gives about 1600 square feet of
steam per minute, and burns about 8 tons of coals in twenty-four
hours. The stack for this boiler is 3-1/2 feet square, and the draught
rises 10 feet per second, and will set white paper in a flame at the
top of it in about a minute. Therefore, this chimney delivers 7200
square feet of air per minute, which is four and a half times the
quantity of heated air, at nearly four times the temperature of heat
that there is of steam produced from the same fire, and delivered to
the cylinder.
"A blast-furnace that burns 100 tons of coal per week is blown by a
5-feet diameter air-cylinder, 4-feet stroke, ten strokes per minute,
double-power, giving about 1600 square feet of air per minute, to
consume 100 tons of coal, besides giving a melting heat to 350 tons of
ore and limestone.
"Crenver engine has 7200 square feet of air to burn 56 tons of coal
per week, which is above eight times the quantity of air used by air
fire-places to what is used in a blast-furnace, and of course must
carry off a great proportion of the heat to the top of the stack, that
might be saved if the engine-fire was a blast instead of an air fire.
"But suppose the idea to be carried still further, by making an
apparatus to condense and take the whole of the heat into the cylinder
instead of its passing up the chimney. By having a very small boiler,
and a blast-cylinder to blow the whole of the blast into the bottom of
the boiler, under a cylinder full of small holes under the water, to
make the heated air give all its heat to the water.
[Illustration]
"The furnace must be made in a tight cast-iron cylinder. Both the
fire-door and the hole through which the blast enters must be quite
tight, as the pressure will be as strong in the fire-place as in the
boiler. The whole of the air driven into the fire-place, with all
the steam raised by its passage up through the water in the boiler,
must go into the cylinder. There will also be the advantage of the
expansion of the air by the heat over and above what it was when taken
cold into the blast-cylinder.
"From the great quantity of coal burnt in blast-furnaces you will find
that a very small blast-cylinder would work a 63-inch cylinder double.
If there is as much heat in a square foot of air as in steam of the
same temperature, the saving will be beyond all conception; but for my
own part I cannot calculate from theory what the advantages will be,
if any, and for that reason, before I drop or condemn the idea, I must
request you will have the goodness, when you have an hour to spare, to
turn your thoughts to this subject, and inform me of your sentiments
on it.
"Perhaps it is like many other wild fancies that fly through the
brain, but I did not like to let it go unnoticed without first getting
your opinion. I hope you will excuse me for so often troubling you.
"St. Ives plans will be delivered to them on Tuesday, when I expect
they will be forwarded to you.
"I hear there is a good course of ore in the adit end at Wheat
Providence Mine.
"A Mr. Sheffield, of Cumberland, writes to Mr. Gould that he has
turned idle his air-furnaces, and smelted his ores by a blast near a
year since.
"His furnace is but 10 feet high and 4 feet diameter, and it melts 28
tons of ore, of from 4 to 5 in the 100 per week, and makes a regel of
from 65 to 70 in the 100, and answers beyond what we calculated for
them.
"Suppose a furnace 20 feet high and 4 feet diameter, it would smelt
eight times the quantity of his, which would be near 900 tons per
month, or nearly double the quantity raised by any one mine in the
country. The expense of the ... would be very trifling.
"To-morrow Dolcoath account will be held, when I expect to have orders
to begin to erect a furnace on the spot.
"This trial of Mr. Sheffield's has put it out of my power to get a
patent, and now I do not know how to get paid.
"I should be content with 5 per cent. on the profits gained by this
plan, and would conduct the business for the mines without salary.
Should you chance to fall on the subject with his Lordship, be pleased
to mention something about the mode of my payment, as his Lordship is
by far the properest person to begin with about my pay, for after his
Lordship has agreed to the sum, and Dolcoath Mine the first to try
the experiment, I think all the county will give way to what he might
propose. But I wish something to be fixed on before all the agents in
the mines know how to be smelters themselves, after which I expect no
favour, unless first arranged.
"I remain, Sir,
"Your very humble servant,
"RICHARD TREVITHICK."
How great was the practical insight his genius gave him, and how
imperfectly his followers have acted on this advice given sixty years
ago!
The chimney that at its top would ignite paper, threw to waste four and
a half times more heated air than was requisite to supply the quantity
of heat which passed through the working cylinder in steam, and at
a temperature nearly four times greater than the temperature of the
steam. It needs only to observe the burnt appearance of a steamboat
funnel of the present day to know how wasteful we still are, or how
very ignorant of improved methods of economizing fuel.
To prevent this waste of heat up the chimney be proposed to do away
with the chimney altogether; the fire-place was to be a close one,
having a blast under the fire-bars of a strength sufficient to force
the air, heated by its passage through the fire, direct through a small
valve into the water in the boiler, by which means all the heat given
by ignition would pass into the steam, and his steam-puffer become an
aërated steam-engine.
From the following it appears that this plan of Trevithick's is now
coming into use as something quite new:--
"In your last impression, under the head of 'Air and Steam combined,
as a Motive Power,' you state 'the invention was described to be that
of Mr. Warsop, but we have recently heard that a few years back (1865)
the same invention had been protected in an earlier patent than Mr.
Warsop's, by Mr. Bell Galloway.'"[3]
Trevithick thought of patenting a plan for reducing copper ore by the
use of a blast, in preference to the usual air-furnace and chimney,
but something similar had been tried by Mr. Gould, and he therefore
proposed to erect a blast-furnace in Dolcoath Mine, receiving a portion
of the saving of fuel as his remuneration. Such a furnace worked there
for many years, until copper smelting was removed from Cornwall to
Wales. The plans for a breakwater at St. Ives were for an undertaking
that has since been in many hands, but without success, except perhaps
for the convenient making of members of Parliament. Some slight
progress has been made by engineers and contractors, but vessels are
not willingly taken to the port, and ratepayers grumble at unprofitable
harbour taxes.
"LONDON, _January 20th, 1811_.
"DEAR TREVITHICK,
"I have not lost any time in mentioning your wishes respecting a
compensation for the plan of smelting copper to Lord Dedunstanville,
who intends mentioning the affair in his next letter to Mr. Reynolds.
Lord Dedunstanville wishes you extremely well, but it is impossible
for him to settle anything apart from the adventurers.
[Footnote 3: See the 'Mechanics' Magazine,' June 3rd, 1870.]
"I am very sorry that anyone should have executed the plan of reducing
copper ore by a blast-furnace before you had put into practice the
idea suggested to me ten years ago. It ascertains, however, that the
contrivance will succeed, although you are certainly reduced to ask
moderate terms, and I know not what can be more moderate than those
you have asked, except that I would recommend some limit as to time.
"The plan you suggest for an engine on a new construction is, I fear,
very doubtful.
"According to the data furnished to me, the air in the blast would be
to that in a common fire-place as 6-1/4 to 1 very nearly, provided
their densities were the same; but you have measured one entering
the furnace at the common temperature, and the other going to the
stack so hot as to set on fire a piece of paper held at the top.
Thus the increase of temperature that augments the elasticity of a
fluid confined, would expand it in the same degree. It is therefore
uncertain from these statements which furnace consumes the greater
quantity of air. I apprehend the general principles of an engine
worked by hot air, through the medium of a blast, would be as
follows:--
"Let any quantity of air be driven into a furnace with the pressure
of an atmosphere, and let it be there expanded ten times. It should
then be taken off ten times as quick, but in that case no power
whatever would be produced, so the external atmosphere would balance
the internal. Now, let the blast be two atmospheres strong, and let
them be expanded ten times, and be taken off ten times as fast, each
stroke will be opposed by one, equal in all to ten; subtract two for
the blast, there remain eight.
"But air so hot would burn every vegetable or animal substance, and
such a furnace I suppose could scarcely be kept air-*tight. If the
heated air is made to act on water, then it becomes a mere question
of how much absolute heat is given out by the fuel, and whether that
excess is more than sufficient to compensate the burden of the blast;
for the water will absorb an immense quantity of heat in changing
itself into steam, and thus reduce the force of the air as to make it
almost impossible for that addition to add so much power as the blast
takes away.
"I have, therefore, no hesitation in saying that this plan will
certainly not do. Write to me by all means whenever anything strikes
you, and you may always depend on having my best advice.
"I am, dear Sir,
"Ever most truly yours,
"DAVIES GIDDY."
Trevithick saw without apparent reasoning, while his friend's
reasonings failed to make plain the full bearing of the questions, and
so cramped the position as to make a change of front difficult--an
operation in which Trevithick excelled. We learn, however, that in 1801
he suggested a blast in copper-ore furnaces, and in 1811 was on the
verge of a discovery that has since revolutionized the iron-smelter's
art by the use of hot blast. Wasted heat from a blast-furnace 10 feet
high led him to the conclusion that by doubling the height of the
furnace, enabling the cold mineral thrown in at the top to take up the
heat wasted through the top of the low furnace, seven-eighths of the
coal would be saved. His idea of sending blast through the furnace of
his steam-boiler to economize heat could have been readily applied to
the iron furnace, and we should have had the modern hot-blast iron
furnaces.
[Rough draft.]
"CAMBORNE, _March 5th, 1812_.
"GENTLEMEN,
"Your favour of the 15th February, with a sketch of your brewery, I
have received; and from which I find the head of water is 30 feet
above the brewery, which makes it difficult to erect the chain and
buckets so as to take advantage of the whole height of water; and as
the stream is so very small, it will not admit of losing any part of
the power.
"To erect a machine so high, to engage the whole fall, would be,
I fear, more expense than the power you would get would warrant;
therefore I would recommend it to be made use of in a cylinder, in the
same way as we use falls of water of 200 feet in our Cornish copper
mines. We allow one-third loss for friction and leakage in those
machines; but your machine being so very small, the loss will exceed
that proportion; therefore I cannot promise you above one-half of the
real weight and fall to be performed on your machinery, and that must
be by a well-executed machine, for a small defect would destroy the
value of so trifling a power.
"As there is no expansion in water, it will be somewhat difficult to
make the machine turn the centres with a fly-wheel, for if the valve
shuts a little too early or too late for the turn of the crank over
the centre, the fly-wheel's velocity must break something by confining
the water between the piston and the bottom of the cylinder, which,
after the valve is shut, cannot make its escape, and not having an
elastic principle, the piston will strike as dead on the water as on a
piece of iron, because, unless the valve is shut by the engine before
the stroke is finished, it cannot shut at all.
"I know persons who have attempted to put fly-wheels on
pressure-engines of this kind, but never yet has one been made to work
rotative. I do not see much difficulty in making an engine of this
kind to work a crank and fly-wheel, by connecting an air-vessel with
the cylinder to receive the pressure and contract and expand and shut
the valves, the same as in steam-engines.
"A machine on this plan ought to be placed as near the low level
as possible. If I furnish you with drawings and directions for the
executing of the work yourselves, I shall charge you fifteen guineas
for them. If I send the machine finished, the charge will be 50_l._
"Your objections respecting steam-engines I do not doubt are correct,
when executed by persons who do not understand the construction of
them. In England some persons privately erected my engine to evade
the patent premium, but have severely paid for their saving knowledge
by accidents and defects in their engineering ability. I have erected
above 100 steam-engines on this principle, but never met with one
accident or complaint against them. To prevent mischief from bad
castings, or from the fire injuring the surface of cast iron, I make
the boilers of wrought iron, and always prove them with a pressure of
water, forced in equal to four times the strength of steam intended to
be worked with.
"Some persons have worked those engines under a pressure above 100
lbs. on the square inch, but in general practice I do not exceed 20
lbs., finding under this pressure the piston will stand six or eight
weeks, and the joints remain perfect, and no risk of bursting the
boiler, it being made of wrought iron, and proved by pressure before
sent off; but cast-iron boilers may, by defects not discernible, and
are very apt to break by the water being left low in the boiler,
and if heated red hot, exploding without the smallest notice; but
wrought-iron boilers, when defective, give way only partially, without
injury to anyone. With respect to the erecting and management of the
engine, you need not have an engineer, for any common tradesman can do
this from the drawings and directions sent with the engine; for, as I
before informed you, farmers and their labourers set up and keep in
order the thrashing-machine engines without my going on the spot or
sending any person to assist them. I never saw a steam-engine rolling
malt, therefore cannot judge the quantity the engine would roll, only
by a comparison with horse labour, against the consumption of coal,
which will be in some cases as about 42 lbs. to one horse; but where
great speed is required in the machine, the coal will be less, as
steam-engines make more revolutions in a minute than horse mills,
therefore the work is done with less friction.
"I have several times applied the steam, after it has worked the
engine, to boil water and other purposes, with as good effect as if
the engine had not been there, therefore the work of the engine will
be a clear profit.
"You say about a 1-horse engine. The boiler would be so small that it
would not be worth applying that steam to any other purpose, as any
large quantity of water would be but slowly heated.
"I find that it does not answer either the purpose of the vendor
or the user of an engine, to make less than a 2-horse power, as
the expense on a very small engine is nearly as much as one of the
power I use for thrashing, those being only 80_l._, and a 2-horse is
60_l._ Respecting the mashing with steam, I never before heard of it,
but from the theory of the plan I think it cannot fail to answer a
far better purpose than any other that can possibly be applied for
extracting the essence of the malt. However, should it not answer your
purpose, it is only the loss of the expense of a few yards of 1-inch
lead pipe.
"In an engine of the size used for thrashing, if the fire is kept
brisk, it will boil, by the steam sent into a separate vessel, near
300 gallons of water per hour.
"The room required to work in is about 7 feet diameter, and 12 feet
high. It would be useless to put you to the expense of drawings, until
you have made up your minds on what you intend to have done.
"I remain, Gentlemen,
"Your most obedient humble servant,
"RICHARD TREVITHICK.
"To ROBINSON AND BUCHANAN, Brewers,
"_Londonderry, Ireland_."
Engineers of the present day do not volunteer such general information
without charge, or give such a variety of practical mechanism
slightly but clearly described, and principles reduced to practice.
An endless chain with buckets is a form of water-wheel not then in
use. A water-pressure engine for so small a quantity of water, with
a fall of about 30 feet, would cause a loss of 50 per cent. from
friction and small defects. The non-elastic character of water made it
unsuitable for a machine requiring a fly-wheel. Air-vessels should be
used to lessen the rigidity of water. Cast-iron boilers dangerous.
Wrought-iron boilers to be tested with a water pressure four times as
great as the proposed working steam pressure. A steam pressure of 20
lbs. to the inch most suitable for engines in charge of inexperienced
persons. The brewers' mash tub to be heated by the waste or surplus
steam.
[Rough draft.]
"CAMBORNE, _December 5th_, 1812.
"GENTLEMEN,
"I have yours of the 20th November. The letter you directed for
Truro never came to hand. I find by your letter that you have been
trying to put into practice the hints I gave you about the chain and
buckets, and that you expect it will answer if properly executed.
You are not the first that has picked up my hints, and stuck fast in
their execution. I make it a rule never to send a drawing until I
have received my fee, and when you remit to me fifteen guineas I will
furnish you with proper drawings and directions to enable you to make
and erect the machine.
"I remain, Gentlemen,
"Your very humble servant,
"RICHARD TREVITHICK.
"ROBINSON AND BUCHANAN, Brewers,
"_Londonderry_."
What a pocket encyclopædia of inventions! from which, as by stealth,
Robinson and Buchanan selected the least applicable, declining a
suitable steam-engine at a very small cost, rather than pay an engineer
for his opinion.
[Rough draft.]
"CAMBORNE, _April 26th_, 1812.
"SIR CHARLES HAWKINS, Bart.,
"Sir,--I have received yours of the 7th, respecting the small
breakwater at St. Ives. As far as I can judge from a rough
calculation, I think it an undertaking likely to pay well; but as
you wished me not to mention anything about your intentions, and not
receiving your orders to make a minute inquiry and estimate, I cannot
answer your letter so fully as I should wish, fearing that giving a
random and imperfect statement might be apt to lead you into errors,
and also make me look simple. If an engineer were employed to survey
and estimate after me, every information in my power is at your
service; therefore be pleased to state particularly what information
you wish, and I will attend to the business and answer your questions
as early as possible.
"I have received a letter from Sir John Sinclair requesting correct
drawings and statements of the thrashing engine to be forwarded to the
President of the Board of Agriculture, which I shall attend to. He
also says that he has sent my letter to the Navy Board, in hopes that
the experiment of propelling vessels by steam may be tried under its
sanction and expense.
"Perhaps it might be proper to wait the answer of the Navy Board
before writing to Mr. Praed about propelling the canal boats. I am
very much obliged to you for writing to Captain Gundry, about the
Wheal Friendship engine. I expect to have a portable steam-whim and
stamps at work at my own expense in a few days, which will prove for
itself its utility; that being the only way to introduce new things. I
would be very much obliged to you to say if Mr. Halse is to pay me for
my past attendance at St. Ives about the breakwater. Enclosed you have
a letter to Sir John Sinclair, unsealed for your inspection, which, if
you approve of, please to forward.
"I remain, Sir,
"Your very humble servant,
"RICHARD TREVITHICK."
Trevithick's skill did not prevent his being reasonably modest,
or cause him to be envious of others; neither did his dear-bought
experience, that one's own pocket must pay for making public one's own
inventions, prevent his again soliciting the assistance of persons of
influence, though it does not seem that Mr. Praed helped forward the
screw-propeller, or that Sir John Sinclair gave direct help, though
he probably made known the high-pressure steam-engine to the marine
experimenters on the Clyde.
[Rough draft.]
"MR. RASTRICK,
"CAMBORNE, _December 7th, 1812_.
"Sir,--I have been waiting your answer to my last, and especially that
part respecting the West India engine, as I have not nor could not
answer their letter to me without first hearing from you; therefore
must beg you will be so good as to answer me by return of post on that
subject. If they get impatient about the time, and refuse to take the
engine, I have no doubt the Plymouth people will take it and several
others; but I very much wish to send one to the West Indies, as there
is a large field open there for engines of this kind. I have received
an order for a thrashing engine for Lord de Dunstanville, of Tehidy;
and as I wish those thrashing engines to be known through the country,
I intend to take one of the engines ordered for Padstow and send it
to Tehidy. One of the Padstow farmers can wait until you make another
for him. Therefore I would thank you to send the first finished by
ship from Bristol for Portreath or Hayle. Send a drum with everything
complete, of which you are a better judge than I. Probably about 3
feet in diameter and 3-1/2 feet long will be sufficient.
"There must be a fly-wheel with a notch to carry the rope, and also a
small notch-wheel on the drum-axle. I think 6-1/2 feet diameter for
the fly, and 9-1/2 inches diameter for the small wheel, will give
speed enough to the drum. Mind to cast a lump, or screw on a balance,
of about 1 cwt., on one side of the fly-wheel. There must be two
stands on the boiler, and a crank-axle, or otherwise a crank-pin, in
the fly-wheel, whichever you please; with a shaft 3 feet long with a
carriage.
"The engine is to stand in a room under the barn, about 7-1/2 feet
high, 7 feet wide, and 14 feet long. The fly-wheel will stand across
the narrow way of the room. The rope will go up through the floor, and
the drum be shifted by a screw, horizontally, on the barn floor, so
as to tighten the rope. I shall put down the top of the boiler level
with the surface, with an arched way to the fire and ash-pit under
ground, to prevent the chance of fire, which the farmers are very much
afraid of. I send you a sketch showing how it is to stand.
"I do not bind you to the size of the drum or wheels, only the room
that the fly-wheel works in is but 7 feet wide.
"Now to Mr. Richards' mill.
"Query 1st.--The length of the piston, and the small variation that
the beam will give it, is so trifling that it will not be felt.
"The cylinders that have been working on their sides for seven years
past, are now working as well as any engine with upright cylinders,
which is a proof that the little rubbing is of no consequence.
"Query 2nd.--The passage in the cock is equal to the passage we
make in our large engines, which is only one-fortieth part of the
piston; and as we shall work with high steam, we do not mind the
pressing through the steam-passage; and as the steam will be very
much expanded, it will not be felt in the passage to the condenser. I
know where we have removed cylinders and put larger ones on the same
nozzles and condensing work, and the engines did good duty.
"Query 3rd.--I find by experience that if you give double the quantity
of injection to an engine one stroke, and none the other, that the
quicksilver in the gauge will stand nearly the same; the cold sides of
the condenser are sufficient to work an engine a great many strokes
without any injection.
"Query 4th.--You may put a hanging to the air-pump bucket, and
foot-valve; either that or a rising one will do very well, but I think
the rising cover and wood face on the top, best.
"Query 5th.--The air-pump bucket is large enough. At Wheal Alfred they
have a 64-inch cylinder; the air-pump is 20 inches, and the stroke
is half that of the engine. They were afraid that it was too small;
they then put another of 14 inches by the side of the first, the same
stroke. The quicksilver tube stands as high with the one 20-inch
bucket as with the two buckets; the engine works best with the one
bucket. I have found by experience that size to be sufficient, and
(especially in an engine that works quickly) make the cistern high
enough to cover the condensing work well with water.
"Query 6th.--My reason for making the forcing pump with duck-valves
is, because they do not bum like the others, and we find them seldom
out of repair; but make it whichever way you think best, and work it
in any way you like.
"Query 7th.--I mean by 3/4 expansive, that the steam is to be shut off
from the cylinder when the piston has moved up from the bottom one
quarter of its stroke. Make the cam to your own mind.
"Query 8th.--I do not think the engine will require a heavier
fly-wheel, as the stones will act as a fly, and the power, though so
very irregular, will be so sudden in its changes, that the speed of
the machinery will not let it be felt. If you make a crank, you may
make the fly-wheel 3 or 4 feet more in diameter. But if with a pin in
the fly-wheel, the beam would come down on the top of it; therefore, I
think it will be better to put a crank, and put the fly-wheel in the
middle of the shaft.
"Query 9th.--The steam will be raised to 25 lbs. to the inch above the
atmosphere, or 40 lbs. to the inch on a vacuum; but I think you need
not calculate for much more strength on that account. It is not the
power that breaks the machinery, but bangs, and not the uniform weight
that this will give.
"Query 10th.--Twenty strokes per minute I propose, which I think a
fair speed.
"Query 11th.--The fire-bars must be of wrought iron; we find them
answer much better than cast iron. Let them be 5/8ths of an inch from
bar to bar, 1 inch thick at the top, 3/8ths of an inch at the bottom,
2 inches deep, 4 feet long, with bits on them at the ends, to prevent
their getting too close together. I find the nearer the fire is to the
door, the better and handier it is to work. All the large engines are
in this way, and we do not find the door or front plate get hot, as
they are lined with brick. Cast the door with a rib to hold a brick on
its edge. Tube, 2 feet 9 inches by 1 foot 11 inches; manhole, 15 by 10
inches.
"Query 12th.--A governor will be required; perhaps as good a place
as any for it, out of the way, will be on the cast iron that carries
the beam; you may turn the fly-wheel whichever way you please. If
this engine is worked with steam of 25 lbs. to the inch above the
atmosphere, and the steam shut off at one-twentieth part of the
ascending stroke of the piston, the power will be as three is to two
of Boulton and Watt's single engines.
"Only two pairs of stones for the present, but calculate those stones
to stand in such a way that another pair may be placed, on a future
day, if wanted. I have not seen Mr. Richards lately. I wish you to
write a form of an order, in your next, such as you wish, and I will
get him to write to you accordingly. Put the engine and drum for Lord
de Dunstanville out of hand neat and well, as it will be well paid
for; and make the stands, &c., in your own way.
"RD. TREVITHICK."
Mr. Richards' flour-mill engine may claim to be the first practical
smoke-burner: keeping the fire much thinner at the inner end of the
grate-bars than at the fire-door end of the grate, allowed of the
freer passage of air through the thinner layer of coal, near the
fire-*bridge, causing the combustion of the passing gas. This idea has,
since the date of Trevithick's letter, led to several smoke-burning
patents. The boiler fire-tube was oval, 2 feet 9 inches by 1 foot 11
inches. The open-topped cylinder was supplied with a heavy and deep
piston serving as a counterweight, and also as a guide in the cylinder
for correcting the angle of the connecting rod. Experience had taught
him that the cold sides of the condenser were sufficient to work an
engine a great many strokes without a supply of injection; and he had
already used high-pressure steam of 25 lbs. to the inch above the
atmosphere, cut off from the cylinder when the piston had performed
one quarter of its course: thus both these things were as first steps
leading to the modern expansive steam-engine and surface condensation.
The simplicity of the engine is remarkable--a high-pressure, expansive,
condensing engine, worked by a single four-way cock, without
cylinder-cover, or parallel motion.
The low first cost, and non-liability to derangement, were always
kept in view; and his confirmed experience in the satisfactory
working of horizontal cylinders prior to 1812 illustrates their
extended application; for at that time scarcely any other engineer had
constructed other than upright cylinder engines. No detail escaped his
observant gaze. The fire-bars were to be 2 inches deep, 1 inch thick at
the top edge, tapered to 3/4ths of an inch at the bottom, giving the
required strength, with free room for air, which in its passage cooled
the bar, carrying the heat into the fire. Years before and after that
period the fire-bar in common use by thoughtless people was a square
iron bar that was always burning and bending.
The letter is descriptive of the high-pressure steam-engine in the
sixteenth year of its age; and its expansive steam, made practical
by Trevithick's high-pressure boilers. This engine only took steam
during the first quarter of its stroke, the remaining three-quarters
were by the expansion. Had it taken steam only during one-twentieth of
its stroke, it would have been more powerful than Boulton and Watt's
low-pressure steam vacuum engine of the same size.
[Rough draft.]
"SIR,
"CAMBORNE, _November 8th, 1812_.
"I have your favour of the 3rd inst., informing me that Messrs. Fox
and Williams have engaged to quarry the stone for e breakwater at
Plymouth, but does not say whether you hold any share with them in
the contract or not. Therefore I cannot understand from your letter
whether you wish to see an engine fitted to the purpose of the
breakwater, or for pumping the water from the foundations of the
Exeter Bridge. Please to inform me which of the two purposes you wish
to see the engine calculated for, and about what time you think you
shall want it, and I will get one finished suitable to the purpose you
intend it for.
"Yours, &c.,
"R. T.
"JAS. GREEN, ESQ., _St. David's Hill, Exeter_.
"N.B.--To what extent have Messrs. Fox engaged, and what parts of the
work do they perform? I think more good might be done by loading,
carrying, and discharging, than by quarrying only."
Trevithick was equally ready with the application of steam-power either
for pumping of water or for boring and removing rock. The use of
chisels and rock-breakers in the Thames in 1803[4] had prepared the way
for the more perfect engine for boring, lifting, and carrying rock from
the quarries to its destination at the Plymouth Breakwater in 1812.[5]
[Footnote 4: See Stonebreaker of 1803, vol. i., p. 239.]
[Footnote 5: See Steam-crane, vol. i., pp. 162, 274.]
"SIR,
"106, HOLBORN HILL, _November 26th, 1812_.
"I am in receipt of yours of the 22nd inst. Mr. Giddy informs me that
Mr. Fox and Mr. Williams are to have 2_s._ 6_d._ per ton for making
the breakwater at Plymouth, and he considers that they can do it for
2_s._, which he thought would give them 50,000_l._ profit. If you meet
those gentlemen, I have to caution you not to LEARN THEM
anything until you make a bargain, as I know Mr. Williams will
endeavour to learn all he can and then you may go whistle.
"If 6_d._ per ton will give 50,000_l._ profit, a halfpenny per ton
would give upwards of 4000_l._ Would they agree to give you that for
your labour only? However, this will depend in a great measure on
the time it will take in doing. If it takes eight years it would be
500_l._ a year for you (according to Mr. Giddy's calculation).
"Your well-wisher,
"HENRY HARVEY.
"MR. RD. TREVITHICK, _Camborne_."
Mr. Harvey knew Trevithick's weakness in money matters. Rennie had been
employed to report on the proposed Plymouth Breakwater, and in 1811 was
desired by Lord Melville, the head of the Admiralty, to proceed with
the work. "The price paid in 1812 for taking and depositing rubble in
the breakwater was 2_s._ 9_d._ per ton; it was afterwards reduced to
1_s._ per ton. A piece of ground was purchased from the Duke of Bedford
at Oreston, up the Catwater, containing 25 acres of limestone, well
adapted for the purposes of the work; and steps were taken to open out
the quarry, to lay down railways to the wharves, to erect cranes."[6]
The idea of the plan to be followed in conveying stone with greater
economy and dispatch than was contemplated by Rennie, originated with
Trevithick, while the former received the credit and the pay, as he
before had done with the steam-dredger.
[Footnote 6: 'Lives of the Engineers,' by Smiles, vol. ii., p. 260.]
[Rough draft.]
"MR. FOX Jun.,
"CAMBORNE, _January 29th, 1813_.
"Sir,--Since I was at Roskrow I have been making trial on boring
lumps of Plymouth limestone at Hayle Foundry, and find that I can
bore holes five times as fast with a borer turned round than by a
blow or jumping-down in the usual way, and the edge of the boring bit
was scarcely worn or injured by grinding against the stone, as might
have been expected. I think the engine that is preparing for this
purpose will bore ten holes of 2-1/2 inches in diameter 4 feet deep
per hour. Now suppose the engine to stand on the top of the cliff, or
on any level surface, and a row of holes bored, 4 feet in from the
edge of the cliff, 4 feet deep, and about 12 inches from hole to hole
for the width of the piece to be brought down at one time, and wedges
driven into the holes to split the rock in the same way as they cleave
moorstone, only instead of holes 4 inches deep, which will cleave a
moorstone rock 10 feet deep when the holes are 14 or 15 inches apart,
the holes in limestone must go as deep as you intend to cleave out
each stope, otherwise the rock will cleave in an oblique direction,
because detached moorstone rocks have nothing to hold them at the
bottom, and split down the whole depth of the rock. In carrying down a
large piece of solid ground the bottom will always be fast, therefore
unless it is wedged hard at the bottom of the hole the stope cannot
be carried down square. In a hole 2-1/2 inches diameter and 4 feet
deep put in two pieces of iron, one on each side of the hole, having a
rounded back, then put a wedge between the two pieces, which might be
made thus, if required to wedge tighter at the bottom of the hole than
at the top.
[Illustration]
"If this plan answers, the whole of the stones would be fit for
service, even for building, and would all be nearly of the same size
and figure. Each piece would be easily removed from the spot by an
engine on a carriage working a crane, which would place them into the
ship's hold at once. It would all stand on a plain surface, and might
be had in one, two, three, or four tons in a stone, as might best
suit the purpose, which would make the work from beginning to end one
uniform piece. Steam machinery would accomplish more than nine-tenths
of all the work, besides saving the expense of all the powder. I find
that limestone will split much easier than moorstone, and I think that
a very great saving in expense and time may be made if the plan is
adopted.
"Please to think of these hints and write me when and where I may
see you to consult on the best method of making the tools for this
purpose before I set the workmen to make them. Any day will suit me,
except Monday, the 8th of February. The sooner the better, as I cannot
set to work to make the tools until we have arranged the plan.
"I am, Sir,
"Your humble servant,
"RD. T."
The successful completion of the Mont Cenis Tunnel in 1871 was mainly
due to an ingenious application of combined mechanical force to boring
tools, before limited to man's strength; but the applied principle
existed sixty years ago, and though not so perfect in detail, yet more
comprehensive. Trevithick's high-pressure steam boring engine enabled
him to penetrate the rock five times as fast as the quarryman's power.
Ten holes, 2-1/2 inches in diameter, 4 feet deep, could be bored in an
hour, and he sagaciously suggested that in quarrying the limestone for
the breakwater, a row of holes should be bored by his engine 4 feet
in from the face of the rock, 2-1/2 inches in diameter, 4 feet deep,
and 12 inches apart; and by dropping into each hole two half-round
pieces of iron, to be driven asunder by a steel wedge, large blocks
would be forced off without the use of gunpowder. The high-pressure
steam-puffer having bored the stone, moved itself toward the broken
mass, lifted it into waggons, and again changing its powers from
steam-crane to steam-locomotive, conveyed it to the port, and lifted
it into the ship's hold. The whole operation was thus aptly described
by the inventor, who then counted on contracting for the breakwater
work:--"Steam machinery will accomplish more than nine-tenths of all
the work, besides saving the expense of all the gunpowder."
[Rough draft.]
"MR. ROBERT FOX, Jun.,
"CAMBORNE, _February 4th, 1813_.
"Sir,--Since I was with you at Falmouth I have made a trial of boring
limestone, and find that the men will bore a hole 1-1/2 inch in
diameter 1 inch deep in every minute, with a weight of 500 lbs. on the
bit. I had no lump more than 12 inches deep; but to that depth I found
that having a flat stem to the bit of the same width as the diameter
of the hole, twisted like a screw, completely discharged the powdered
limestone from the bottom of the hole without the least inconvenience.
"From the time the two men were employed boring a hole 12 inches deep,
I am convinced to a certainty that the engine at Hayle will bore as
many holes in one day as will be sufficient to split above 100 tons of
limestone, and would draw that 100 tons of stone from the spot and put
them into the ship's hold in one other day. The engine would burn in
two days 15 bushels of coal, four men would be sufficient to attend on
the engine, cleave the stone, and put it into the ship's hold. I think
it would not amount to above 9_d._ per ton, every expense included,
but say 1s., which I am certain it will not amount to. Perhaps it may
not be amiss to withhold the method of executing this work until the
partners have more fully arranged with me the agreement as to what I
was to receive for carrying the plan into execution. I do not wish
that anyone but your father should be made acquainted with the plan,
and have no doubt he will have sufficient confidence in the scheme to
adopt it. I shall be glad to hear from you soon, as I intend to go to
Padstow in a few days and shall not return under a fortnight.
"Your humble servant,
"RD. TREVITHICK.
"N.B.--I this day received a letter from Mr. Gould, requesting to know
what the expense of an engine and apparatus would be for clearing
Falmouth Harbour, which I have sent by the post."[7]
[Footnote 7: See letter, 4th February, 1813, vol. i., p. 248.]
It had been and still is the custom to bore rock either with a long
and heavy jumper-chisel, lifted a foot or two, and falling by its own
weight, pounding to powder a portion of the rock, or by the use of a
much smaller chisel called a borer, struck by a hammer. Trevithick
having made his steam-engine perform those jumper and borer movements,
turned his attention to the improvement of the borer, and found that
a revolving bit was more suitable for drilling limestone than the
borer-chisel. The powdered stone was removed from the hole by giving
a screw form to the stem of the bit. Many years afterwards precisely
similar bits for boring wood were patented as new things, and are
still used. Within five months of his first communication with the
contractors for the Plymouth Breakwater he had designed and made an
engine to bore, lift, and convey to the ship's hold 50 tons of stone
daily at less than half the cost Rennie was then paying for it.
[Rough draft.]
"SIR,
"CAMBORNE, _February 4th, 1813_.
"I have your letter of the 31st January requesting to know the time
in which the engine will be ready for the bridge at Exeter, and also
about giving an additional power to it.
"The engine shall be ready in six weeks from the end of January,
and shall be capable of lifting the 10-inch bucket you have ordered
instead of the 9-inch before proposed, which was to have delivered 500
gallons of water 12 feet high per minute; but now the engine shall
be made to lift in the same proportion as a 9-inch is to a 10-inch
bucket, which will be 617 gallons of water per minute instead of 500
gallons, as was before agreed on, and I shall charge you accordingly.
I observe that you have ordered the pump, and from the description
you give of it, I think it will answer very well. If you wish a
perpendicular cylinder instead of a horizontal, I can construct it in
that way, but it will not be so convenient for a portable engine. I
have now engines with horizontal cylinders at work above ten years,
and find them answer equally as well as a perpendicular cylinder.
"I remain, Sir,
"Your very humble servant,
"RICHD. TREVITHICK.
"JAS. GREEN, Esq., _Exeter_."
Engineers nowaday are not in the habit of designing and constructing a
steam-engine in six weeks, or willing to alter the agreed form from the
horizontal to the vertical without charge.
[Rough draft.]
"Mr. Robert Fox, jun., informed me the other day that you had the sole
direction of the work at Plymouth. Had I known it at the time you
were at Scorier I should have communicated to you my ideas relating
to the application of machinery there; but until a few days since I
had an idea that the young Mr. Fox was about to take an active part
in the management, which I now find was never his intention, only he
very much wishes to have an experiment tried to see to what extent
an engine was capable of performing as against men. An engine is now
preparing for that purpose."
"SIR,
"CAMBORNE, _February 24th, 1813_.
"On my return from Padstow this evening, where I have been for the
last fortnight, I found your letter of the 11th inst. respecting the
getting an apparatus ready for the Plymouth undertaking. Before I set
about it I wish to see you and Mr. Fox, and will call any day you may
appoint. Waiting your reply,
"I remain, Sir,
"Your very humble servant,
"R. TREVITHICK.
"MR. ROBERT FOX, Jun., _Falmouth_"
After three months of experimental scheming, without a thought of
keeping his inventions secret, Trevithick for a moment became worldly
wise, and asked for a written agreement before sending his locomotive
boring engine to the breakwater.
[Rough draft.]
"MR. FOX,
"CAMBORNE, _14th March, 1814_.
"Sir,--I expect to be called to London immediately after the end of
this month. The engine with the boring apparatus for Plymouth remains
at Redruth. I very much wish to see you on that business before I
leave home, and would be much obliged by your dropping me a note by
post, saying what day it would be convenient for me to wait on you.
"R. T."
The rock-boring machine was completed, and reached the breakwater two
months after his interview with the Foxes, who were prominent in the
quarrying work. "The engine for Plymouth will be put to break the
ground as soon as I can find time to go up there."[8] It was impossible
for any one man, single-handed, to make perfect such numerous practical
inventions as were undertaken by Trevithick at that time. His letter
of a few months before[9] reveals the facility with which he moulded
the steam-engine to his requirements. "The ploughing engine that I sent
you a drawing for, after being used for that purpose, was to have been
sent to Exeter for pumping water. I have been obliged to take the small
portable engine from Wheal Alfred Mine, and have a new apparatus fitted
to it for Plymouth Breakwater. A small engine which I had at work at a
mine I have been obliged to send to the farmers for thrashing." Messrs.
Fox would probably require many engines for the Plymouth Breakwater,
having engaged with Government to deliver three million tons of stone;
and to prevent delay, the boring apparatus was applied to an engine
made for another purpose, while drawings for a new and more suitable
engine for boring stone were sent to Mr. Rastrick.
[Footnote 8: Trevithick's letter, May 20, 1813, chap. xxi.]
[Footnote 9: See letter to Mr. Rastrick, January 26, 1813, chap. xviii.]
He engaged that an engine should bore holes to split 100 tons of
limestone a day; and that on the following day it should, as a
locomotive and steam-crane, load that quantity in waggons, convey it
from the quarry to the port of shipment, and then by steam-crane place
it in the hold of a vessel. The whole of the work to be done by 11
cwt. of coal and four men. The gross cost would be 1_s._ per ton for
breaking and removing, though at that time Mr. Rennie was paying 2_s._
9_d._ a ton, which in after years was reduced to 1_s._, just what
Trevithick said was a fair price.
While this ready application of the high-pressure steam-engine was
going on in England, it had also extended to, and was coining money in
the Mint at Lima, where Trevithick contemplated going to look after
it, intending to land at Buenos Ayres, and make his way across the
continent of South America and the mountains of the Cordilleras as best
he could, leaving the home field he had made so fertile to be reaped by
others, and the stone-boring locomotive to be forgotten for many years.
[Rough draft.]
"SIRS,
"PENZANCE, _December 9th, 1815_.
"Your very great neglect in not writing.... Herland engine will
work, I expect, in about fifteen days. It is a plunger of 33 inches
diameter, 10-feet stroke, with a double packing around the top of the
plunger-pole, in the same way as the steam is turned into the stuffing
box of a double engine to exclude the air, only there is a small tube
from the bottom of the boiler to the middle of the stuffing box to
prevent the escape of steam.
"I am sorry to find by Mr. Uville's letter that the Mint engine
does not go well. I wish you had put the fire under the boiler and
through the tube, as I desired you to do, in the usual way of the long
boilers; then you might have made your fire-place as large as you
pleased, which would have answered the purpose and worked with wood
just as well as with coal. I always told you that the fire-place in
the boiler was large enough for coal, but not for wood; also if you
found that the cock did not open and shut in proper time, to make the
gear to it work the same as the Dolcoath puffer whim-engine instead
of the circular gear. The boiler is strong enough and large enough to
work this engine with 30 lbs. to the inch, thirty strokes per minute.
I hope to leave Cornwall for Lima about the end of this month, and go
by way of Buenos Ayres, and cross over the continent of South America,
because I cannot get any other passage. None of the South Sea whalers
will engage to take me to Lima, as they say they may touch at Lima or
they may not. Unless I give them an immense sum they will not engage
to drop me there. To be brought back to England after a two years'
voyage without seeing Lima would be a very foolish trip. To make a
certainty I shall take the first ship for Buenos Ayres, preparations
for which I have already made."
This unfinished rough draft was intended for one of the men who had
gone to Lima, less fruitful in emergency than Trevithick, who, without
a moment's hesitation, would have constructed a fire-place outside the
boiler, when the internal tube fire-place was found to be too small for
a wood fire. Trevithick's proposing sixty years ago to make his way
over the almost unknown track from Buenos Ayres, on the Atlantic, to
Lima, on the Pacific, was perhaps characteristic of his daring spirit,
that turned all things to good account; but he dreamed not that his
grandson and namesake would at this time be conducting the steam-horse
on the same line of march on the Central Argentine Railway from
Rosario to Cordoba, in the Argentine Republic.
[Rough draft.]
"GENTLEMEN,
"CAMBORNE, _August 19th, 1813_.
"I received yours at Bridgenorth of the 19th July, ordering a
steam-engine for rolling sugar-cane. I immediately set the founders to
work on one for you, which is to be ready by my return to Bridgenorth
about the end of September. I intend to ship it for Bristol, and will
call on you on my journey down to Cornwall, as I intend to set it to
work at Bristol for your inspection before it is put on board ship.
The price I cannot accurately say at present, as the engine now making
is on a new principle; and as it will be more simple in construction,
I hope to be able to render it within the price before stated to you.
As it is on a new plan I cannot fix the price until I know the cost of
making. All I can say at present is that it shall not exceed what I
stated to you in my former letter.
"I remain, Sirs,
"Your humble servant,
"RD. TREVITHICK.
"MESSRS. PINNEYS AND AMES, _Bristol_."
The engine for the sugar plantations in Jamaica, on an improved plan,
was to be constructed in the short space of six weeks, and if a saving
in cost was effected, the inventor would hand the whole of it to the
purchaser.
[Rough draft.]
"SIR,
"PENZANCE, CORNWALL, _March 8th, 1816_.
"I received your favour of the 25th January, but did not answer it in
due course, because I was then erecting a very large engine, which is
the first on a new plan. This engine, which has been at work about
a month, performs exceedingly well. The cost of erection and the
consumption of coal are not above one-third of a Boulton and Watt's,
to perform the same work. An engine of 4-horse power will not require
a space of more than 5 feet high, 5 feet long, and 3 feet 6 inches
wide. In some instances I employ a balanced wheel 5 feet in diameter.
The water required will be a pint and a half per minute. The coal,
one quarter of a bushel or 21 lbs. per hour. The price of a machine,
finished and set to work, 100 guineas. It does not require either wood
or mason work, but stands independent of every fixture, and may be set
to work in half an hour after being brought on your premises.
"Your obedient servant,
"RICHD. TREVITHICK.
"DR. MOORE, M.D., _Exeter_."
A 4-horse-power portable high-pressure steam-puffer engine cost
105_l._, with internal fire-tube and machinery attached to the boiler,
ready for work in half an hour after lighting the fire, consumed 21
lbs. of coal and 11 gallons of water for each hour's work, at a cost of
threepence.
The reader's attention has been very imperfectly drawn to the numerous
subjects touched on in these remnants of Trevithick's correspondence
between the years 1804 and 1816; among them may be traced the portable
high-pressure steam-engine, the tubular cylindrical boiler of wrought
iron, the economy of expansive working with steam of 100 lbs. on the
inch, but limiting it to 20 lbs. when not in the charge of experienced
workmen, and testing boilers by water pressure to four times the
intended working pressure.
The economy of heat in smelting furnaces and in the aërated
steam-engine were bold means to large results. The cheap 100l.
steam-engine of 1812, with open-top cylinder and rigid simplicity
of gear, resembling Newcomen's first atmospheric engine, was really
a high-pressure steam expansive engine, with the germ of surface
condensation, as ready to convey itself from mine to mine or from farm
to farm, and to join in performing labourer's work, even to boring and
conveying rock by land or sea, as the most perfect of modern engines;
and yet this unadorned engine, as seen in the agricultural engine
of the following chapter, followed the excellent mechanism of the
double-acting Kensington model of 1798, and the still more beautiful
engine of the 1802 patent and London locomotive.