"Penydarran Place,December 26th, 1804."Dear Sir,"I have been favoured with your letter, and in answer, respecting Mr. Mitchell, I am at a loss to know from your letter what kind of iron he may likely want. If you will direct him to write to me, and explain himself, I will immediately reply to him and do what I can to assist and serve him. I believe there are vessels going over frequently from Cardiff to Cornwall with coals, that he might have part in cargo and the remainder in coals. I am happy to give you the most satisfactory account of our 'Trevithick's engine' going on well. It has now been at work many months, and is by far the best engine we have. We have for weeks weighed the coal, and knowing the work itdoes, can speak with confidence. Its 18 inches diameter steam-cylinder consumes as near as can be 3 tons of coal in twenty-four hours, or 18 tons per week; and in this time it rolls with ease 130 tons long weight of iron from the puddling furnaces, at the same heat, into bars of 3 inches by about half an inch thick. Now, one on Messrs. Boulton and Watt's plan, of '24 inches' steam-cylinder, at our neighbouring works at Dowlais, employed in doing exactly the same kind of work, consumesfullas much coal, and rolls only 90 tons in the week. These being facts, open for any person daily to see, must convince any dispassionate man of the superiority of 'Trevithick's engines,' and that the saving of fuel is nearly one-third, besides the other advantages of saving water and grease, which is no little. The packing of the piston now gives us little or no trouble, it goes from a fortnight to a month, opening the top now and then to screw it down, as it gets slack, which should be attended to. We use no grease or oil in packing the piston or working the engine, having found blacklead mixed with water, and poured 'a little now and then' through a hole on the top into the steam-cylinder, suits the packing of the piston much better, and is cheaper than anything else. About 1s.worth of blacklead will last our engine a week. We are now so thoroughly convinced of the superiority of these engines that I have just begun another of larger size. The boiler is to be 24 or 26 feet long, 7 feet diameter, fire-tube at wide end 4 feet 4 inches, and at narrow end, where it takes the chimney, 21 inches, steam-cylinder 23 inches diameter. This boiler, on account of the length of its tube withinside, will, I have no doubt, get steam in proportion, and work the engine with much less coals than our present one. Trevithick is at Coalbrookdale, Manchester, &c., &c., very busy, a great number of engines being in hand in that part of the world; and I think by perseverance the prejudice is wearing away very fast, and in spite of all Messrs. Boulton and Watt's opposition, they must and will take the lead of theirs. Any person now wanting engines, must be next kin to an idiot to erect one of Boulton's in preference to Trevithick's. I find there is a small one making near you by Mr. Vivian. I hope they have corresponded with Trevithickabout the proportions of it; if they have not, I shall be particularly obliged to you to desire them to do so, for by his experience of what he has done they may be benefited, for it would be a shocking thing to have a bad engine put up for the first time in his native county."Mrs. Homfray unites with me in best compliments, and wishing you many happy returns of the season."I remain,dear Sir,"Your most obedient servant,"Samuel Homfray."To Mr. Davies Giddy."
"Penydarran Place,December 26th, 1804.
"Dear Sir,
"I have been favoured with your letter, and in answer, respecting Mr. Mitchell, I am at a loss to know from your letter what kind of iron he may likely want. If you will direct him to write to me, and explain himself, I will immediately reply to him and do what I can to assist and serve him. I believe there are vessels going over frequently from Cardiff to Cornwall with coals, that he might have part in cargo and the remainder in coals. I am happy to give you the most satisfactory account of our 'Trevithick's engine' going on well. It has now been at work many months, and is by far the best engine we have. We have for weeks weighed the coal, and knowing the work itdoes, can speak with confidence. Its 18 inches diameter steam-cylinder consumes as near as can be 3 tons of coal in twenty-four hours, or 18 tons per week; and in this time it rolls with ease 130 tons long weight of iron from the puddling furnaces, at the same heat, into bars of 3 inches by about half an inch thick. Now, one on Messrs. Boulton and Watt's plan, of '24 inches' steam-cylinder, at our neighbouring works at Dowlais, employed in doing exactly the same kind of work, consumesfullas much coal, and rolls only 90 tons in the week. These being facts, open for any person daily to see, must convince any dispassionate man of the superiority of 'Trevithick's engines,' and that the saving of fuel is nearly one-third, besides the other advantages of saving water and grease, which is no little. The packing of the piston now gives us little or no trouble, it goes from a fortnight to a month, opening the top now and then to screw it down, as it gets slack, which should be attended to. We use no grease or oil in packing the piston or working the engine, having found blacklead mixed with water, and poured 'a little now and then' through a hole on the top into the steam-cylinder, suits the packing of the piston much better, and is cheaper than anything else. About 1s.worth of blacklead will last our engine a week. We are now so thoroughly convinced of the superiority of these engines that I have just begun another of larger size. The boiler is to be 24 or 26 feet long, 7 feet diameter, fire-tube at wide end 4 feet 4 inches, and at narrow end, where it takes the chimney, 21 inches, steam-cylinder 23 inches diameter. This boiler, on account of the length of its tube withinside, will, I have no doubt, get steam in proportion, and work the engine with much less coals than our present one. Trevithick is at Coalbrookdale, Manchester, &c., &c., very busy, a great number of engines being in hand in that part of the world; and I think by perseverance the prejudice is wearing away very fast, and in spite of all Messrs. Boulton and Watt's opposition, they must and will take the lead of theirs. Any person now wanting engines, must be next kin to an idiot to erect one of Boulton's in preference to Trevithick's. I find there is a small one making near you by Mr. Vivian. I hope they have corresponded with Trevithickabout the proportions of it; if they have not, I shall be particularly obliged to you to desire them to do so, for by his experience of what he has done they may be benefited, for it would be a shocking thing to have a bad engine put up for the first time in his native county.
"Mrs. Homfray unites with me in best compliments, and wishing you many happy returns of the season.
"I remain,dear Sir,"Your most obedient servant,"Samuel Homfray.
"To Mr. Davies Giddy."
The evidence in this contest between the Watt low-pressure steam vacuum engine and the Trevithick high-pressure steam-puffer engine is in favour of the new principle; for the steam-engine with an 18-inch cylinder did fifty per cent. more work than the vacuum engine with a 24-inch cylinder with an equal quantity of coal, though the latter was seventy-five per cent. larger than the former; and a still greater economy was expected from the larger boiler to be built, 26 feet long, 7 feet in diameter, with internal fire-tube 4 feet 4 inches diameter at the fire end, tapering to 21 inches at the chimney end.
Thus in 1804 the cylindrical boiler in Wales had nearly reached its present form, and Homfray thought that none but idiots would prefer the Watt engine; forgetting that Trevithick's near friends and neighbours were carrying on a similar contest at Dolcoath Mine.
"Penydarran Place,January 2nd, 1805."Mr. Davies Giddy,"Dear Sir,—I have duly received your favour enclosing a letter for Mr. Trevithick, and which I, according to your desire, forwarded to him at Manchester, where he now is; and aletter directed to him, to the care of Mr. Whitehead, Soho Foundry, Manchester, will find him, as he will stay a little time there, being very busy. I had lately the pleasure of writing to you, and gave you the account of our engine working, and the satisfaction it gives; I have nothing more to add on the subject, but that it is now at work, going on as usual, and I should be happy for you to have a sight of it."We are beginning another of a larger size, and I have no doubt but by making the cylindrical boiler larger, so as to take a longer tube withinside it, by which means the fire will spend itself before it leaves the tube to go up the chimney, that we shall work to much better advantage in point of fuel than we do at this present one, as this boiler is so short that a great deal of the flame of the fire goes up the chimney. We are now better acquainted with the different proportions than we at first were, for which reason I am anxious that one now making by Mr. Vivian should be made according to the directions of Mr. Trevithick."I beg leave to offer you the compliments of the season, and many happy returns, and"Remain, respectfully, dear Sir,"Your most obedient servant,"Samuel Homfray."
"Penydarran Place,January 2nd, 1805.
"Mr. Davies Giddy,
"Dear Sir,—I have duly received your favour enclosing a letter for Mr. Trevithick, and which I, according to your desire, forwarded to him at Manchester, where he now is; and aletter directed to him, to the care of Mr. Whitehead, Soho Foundry, Manchester, will find him, as he will stay a little time there, being very busy. I had lately the pleasure of writing to you, and gave you the account of our engine working, and the satisfaction it gives; I have nothing more to add on the subject, but that it is now at work, going on as usual, and I should be happy for you to have a sight of it.
"We are beginning another of a larger size, and I have no doubt but by making the cylindrical boiler larger, so as to take a longer tube withinside it, by which means the fire will spend itself before it leaves the tube to go up the chimney, that we shall work to much better advantage in point of fuel than we do at this present one, as this boiler is so short that a great deal of the flame of the fire goes up the chimney. We are now better acquainted with the different proportions than we at first were, for which reason I am anxious that one now making by Mr. Vivian should be made according to the directions of Mr. Trevithick.
"I beg leave to offer you the compliments of the season, and many happy returns, and
"Remain, respectfully, dear Sir,"Your most obedient servant,"Samuel Homfray."
Trevithick, always busy, was just now doing the work of a host, for everybody had to be taught how to make high-pressure steam-engines; and the Newcastle locomotive, the Thames steam-dredging, and other special applications of steam-power required his presence, especially the fight with Watt at Dolcoath Mine, where Andrew Vivian, as mine manager, was erecting a high-pressure steam-puffer whim-engine to compete with a Watt low-pressure steam vacuum whim-engine.
"The adventurers grumbled because Captain Trevithick was so often away from the mine. Glanville, the mine carpenter,the head man over the engines, made a trial between Trevithick's high-pressure puffer whim and Watt's low-pressure condenser. When Captain Trevithick heard of it, he wrote down from London that he would bet Glanville 50l.that his high-pressure puffer should beat Watt's low-pressure condenser. Then he came down from London and found that the piston of his engine was half an inch smaller in diameter than the cylinder. When a new piston was put in, she beat Boulton and Watt all to nothing. Persons were chosen to make a three or four weeks' trial, and when it was over, 'a little pit was found with coal buried in it, that Glanville meant to use in the Watt engine.'"[66]
"The adventurers grumbled because Captain Trevithick was so often away from the mine. Glanville, the mine carpenter,the head man over the engines, made a trial between Trevithick's high-pressure puffer whim and Watt's low-pressure condenser. When Captain Trevithick heard of it, he wrote down from London that he would bet Glanville 50l.that his high-pressure puffer should beat Watt's low-pressure condenser. Then he came down from London and found that the piston of his engine was half an inch smaller in diameter than the cylinder. When a new piston was put in, she beat Boulton and Watt all to nothing. Persons were chosen to make a three or four weeks' trial, and when it was over, 'a little pit was found with coal buried in it, that Glanville meant to use in the Watt engine.'"[66]
Pooly, Smith, and others, say that Trevithick's Dolcoath puffer had the outer case of the boiler of cast iron, the fire-tube of wrought iron, the cylinder horizontal, and fixed in the boiler. Captain Joseph Vivian saw Trevithick's whim in Stray Park Mine about 1800 or 1801, and a similar one was erected in Dolcoath, and after a year or two a Boulton and Watt low-pressure whim was put up to beat it. The trial was in favour of the Watt engine, but everybody said the agents were told beforehand which way the report ought to go; so the engine thatpuffed the steam up the chimneywas beaten.
Trevithick, who was busily engaged in Manchester at that time, the early part of 1805, when informed of what was going on in Cornwall, wrote:—
"I fear that engine at Dolcoath will be a bad one. I never knew anything about its being built until you wrote to me about Penberthy Crofts engine, when you mentioned it. I then requested Captain A. Vivian to inform me the particulars about it, and I find that it will not be a good job. I wish it never was begun."[67]
"I fear that engine at Dolcoath will be a bad one. I never knew anything about its being built until you wrote to me about Penberthy Crofts engine, when you mentioned it. I then requested Captain A. Vivian to inform me the particulars about it, and I find that it will not be a good job. I wish it never was begun."[67]
"Camborne,February 18th, 1806."Mr. Giddy,"Sir,—On my return from town I altered the pressure of the steam-engine at the bottom of the hill, Dolcoath. Before I returned there was a trial between mine and one of Boulton's; both engines in the same mine and drawing ores from the same depth. The result was, Boulton's beat the pressure-engine as 120 to 55. Since it was altered there have been three other trials; the result was 147 to 35 in favour of the pressure of the steam-engine. They are now on trial for another month, and at the next accountthey intend to order a new boiler for the great engine, and work with high-pressure steam and condenser, provided this engine continues to do the same duty as was done in the former trials. This engine is now drawing from a perpendicular shaft, and Boulton and Watt's from an underlay shaft; but to convince Captain Jos. Vivian, we put it to draw out of the worst shaft in the mine, and then we beat more than three to one; we lifted in forty-seven hours, 233 tons of stuff 100 fathoms with 47 bushels of coal. The engine was on trial sixty-six hours, but nineteen hours were hindered by the shaft and ropes, &c., which made the consumption of coals about ¾ths of a bushel per hour. The fire-tube is 2 feet 3 inches diameter, and the fire-bars were only 14 inches long. The fire-place was but 2 feet 3 inches wide by 14 inches long, and the fire about 4 or 5 inches thick; it raised steam in plenty; it was as bright as a star. The engine is now doing the work of two steam-whims; the other steam-whim in the Valley is turned idle, and both shafts will not more than half supply it. 233 tons are equal to nearly 2000 kibbals, which were drawn in forty-seven hours."Mr. Harris has a 12-inch cylinder making at Hayle, for Crenver, and Mr. Daniel has a 14-inch for Perran-sand, and a great number are waiting for the trial of this month,before altering their boilers to the great engines."The steam-whim that is now turned idle at the Valley was 13½-inch cylinder, 4-feet stroke; it turned the whim one revolution to one stroke, and lifted the kibbal the same height at a stroke as my engine did, and I think took the same number of gallons of steam to lift a kibbal as mine did. Their steam wasnot above 4 lbs. to the inch;mine was near 40 lbs. to the inch; yet I raised my steam of near 40 lbs. with a third of the coals by which they got theirs of 4 lbs. to the inch. This is what I cannot account for, unless it is by getting the fire very small and extremely hot. Another advantage I have is, that there is no smoke that goes off from my fire to clog the fire sides of the boiler, while the common boilers get soot half an inch thick, and the mud falls on the bottom of the boiler, where the fire ought to act; but in these new boilers the mud falls to the bottom, where there is no fire, and both the inside and outside of the tube are clean and exposed both to fire and water. This fire-place of 14 inches was 5 feet long when I came down, and then the coal did not do above one-seventh of the duty that it now does."I would be very much obliged to you for your opinion on what I have stated, and whatadvantage you think the great engine is likely to get from working with steam about 25 lbs. to the inch, and shut off early in the stroke, so as to have the steam about 4 lbs. to the inch when the piston is at the bottom. I think this, with the advantage of the fire-place, will make a great saving."The present fire-place is 22 feet from fire-door to fire-door, 9 feet wide, and 7 feet thick in fire. There is not one-tenth of the coals that are in the fire-place on fire at the same time; it will hold 30 tons of coals at one time, and I think that a great deal of coal is destroyed by a partial heat before it takes fire. A boiler on the new plan will not cost more than two-thirds of the old way, and will last double the time, and can be cleaned in three hours. It requires twenty-four hours in the old way, and we need to clean the boilers only one-fourth the number of times."Though these trials have shown so fairly that it is a great advantage, my old acquaintances are still striving with all their might to destroy the use of it; but facts will soon silence them."I am about to enter into a contract with the Trinity Board for lifting up the ballast out of the bottom of the Thames for all the shipping. The first quantity stated was 300,000 tons peryear, but now they state 500,000 tons per year. I am to do nothing but wind up the chain for 6d.per ton, which is now done by men. They never lift it above 25 feet high. A man will now get up 10 tons for 7s.My engine at Dolcoath has lifted above 100 tons that height with 1 bushel of coals. I have two engines already finished for this purpose, and shall be in town in about fifteen days to set them at work. They propose to engage with me for twenty-one years. The outlines of the contract they have sent me down, which I think is on very fair terms. I would thank you for your answer before I leave this county."I am, Sir,"Your very humble servant,"R. Trevithick.
"Camborne,February 18th, 1806.
"Mr. Giddy,
"Sir,—On my return from town I altered the pressure of the steam-engine at the bottom of the hill, Dolcoath. Before I returned there was a trial between mine and one of Boulton's; both engines in the same mine and drawing ores from the same depth. The result was, Boulton's beat the pressure-engine as 120 to 55. Since it was altered there have been three other trials; the result was 147 to 35 in favour of the pressure of the steam-engine. They are now on trial for another month, and at the next accountthey intend to order a new boiler for the great engine, and work with high-pressure steam and condenser, provided this engine continues to do the same duty as was done in the former trials. This engine is now drawing from a perpendicular shaft, and Boulton and Watt's from an underlay shaft; but to convince Captain Jos. Vivian, we put it to draw out of the worst shaft in the mine, and then we beat more than three to one; we lifted in forty-seven hours, 233 tons of stuff 100 fathoms with 47 bushels of coal. The engine was on trial sixty-six hours, but nineteen hours were hindered by the shaft and ropes, &c., which made the consumption of coals about ¾ths of a bushel per hour. The fire-tube is 2 feet 3 inches diameter, and the fire-bars were only 14 inches long. The fire-place was but 2 feet 3 inches wide by 14 inches long, and the fire about 4 or 5 inches thick; it raised steam in plenty; it was as bright as a star. The engine is now doing the work of two steam-whims; the other steam-whim in the Valley is turned idle, and both shafts will not more than half supply it. 233 tons are equal to nearly 2000 kibbals, which were drawn in forty-seven hours.
"Mr. Harris has a 12-inch cylinder making at Hayle, for Crenver, and Mr. Daniel has a 14-inch for Perran-sand, and a great number are waiting for the trial of this month,before altering their boilers to the great engines.
"The steam-whim that is now turned idle at the Valley was 13½-inch cylinder, 4-feet stroke; it turned the whim one revolution to one stroke, and lifted the kibbal the same height at a stroke as my engine did, and I think took the same number of gallons of steam to lift a kibbal as mine did. Their steam wasnot above 4 lbs. to the inch;mine was near 40 lbs. to the inch; yet I raised my steam of near 40 lbs. with a third of the coals by which they got theirs of 4 lbs. to the inch. This is what I cannot account for, unless it is by getting the fire very small and extremely hot. Another advantage I have is, that there is no smoke that goes off from my fire to clog the fire sides of the boiler, while the common boilers get soot half an inch thick, and the mud falls on the bottom of the boiler, where the fire ought to act; but in these new boilers the mud falls to the bottom, where there is no fire, and both the inside and outside of the tube are clean and exposed both to fire and water. This fire-place of 14 inches was 5 feet long when I came down, and then the coal did not do above one-seventh of the duty that it now does.
"I would be very much obliged to you for your opinion on what I have stated, and whatadvantage you think the great engine is likely to get from working with steam about 25 lbs. to the inch, and shut off early in the stroke, so as to have the steam about 4 lbs. to the inch when the piston is at the bottom. I think this, with the advantage of the fire-place, will make a great saving.
"The present fire-place is 22 feet from fire-door to fire-door, 9 feet wide, and 7 feet thick in fire. There is not one-tenth of the coals that are in the fire-place on fire at the same time; it will hold 30 tons of coals at one time, and I think that a great deal of coal is destroyed by a partial heat before it takes fire. A boiler on the new plan will not cost more than two-thirds of the old way, and will last double the time, and can be cleaned in three hours. It requires twenty-four hours in the old way, and we need to clean the boilers only one-fourth the number of times.
"Though these trials have shown so fairly that it is a great advantage, my old acquaintances are still striving with all their might to destroy the use of it; but facts will soon silence them.
"I am about to enter into a contract with the Trinity Board for lifting up the ballast out of the bottom of the Thames for all the shipping. The first quantity stated was 300,000 tons peryear, but now they state 500,000 tons per year. I am to do nothing but wind up the chain for 6d.per ton, which is now done by men. They never lift it above 25 feet high. A man will now get up 10 tons for 7s.My engine at Dolcoath has lifted above 100 tons that height with 1 bushel of coals. I have two engines already finished for this purpose, and shall be in town in about fifteen days to set them at work. They propose to engage with me for twenty-one years. The outlines of the contract they have sent me down, which I think is on very fair terms. I would thank you for your answer before I leave this county.
"I am, Sir,"Your very humble servant,"R. Trevithick.
In the trial at Dolcoath during his absence the high-pressure steam-puffer whim was beaten by Watt's low-pressure steam vacuum whim-engine as 55 to 120; but having corrected some oversight in the puffer-engine, it then beat Watt as 147 to 35. The trial was to be continued for a month; and provided the superiority of his whim-engine could be maintained, the adventurers would allow him to apply his high-pressure boilers to their large Boulton and Watt pumping engine. The trial with the whim-engines was for the greatest number of kibbals of mineral raised to the surface by the least consumption of coal. A dispute arose on the difference of the shafts, the one causing more friction to the moving kibbal than the other, when Trevithick agreed to take the worst shaft in the mine. On a trial during sixty-six hours Watt's engine was beaten by more than four times; and as Trevithick's engine did the work that before required two engines, one of the low-pressure steam Watt engines was removed that the engine working with 40 lbs. on the inch might perform the whole work.
"My fire-tube is 2 feet 3 inches in diameter, and the fire-bars only 14 inches long, and the fire only about 4 or 5 inches thick; it raised steam in plenty, and was as bright as a star." These words certainly imply the use of the blast-pipe, making the fire as bright as a star, and enabling the small boiler to give the required supply of steam. Several high-pressure puffer-engines had been ordered, and many persons were waiting the conclusion of the month's public trial to enable them to judge between the Watt and the Trevithick engine.
"Camborne,March 4th, 1806."Mr. Giddy,"Sir,—The day after I wrote to you the first letter, I received yours, and this day I have yours of the 1st instant."I am very much obliged to you for the figures you have sent me. I am convinced that thepressure of steam will not hold good as theory points it out, because on expanding it will get colder, and of course lose a part of its expansive force after the steam-valve shuts. I think there can be no risk in making this trial on Dolcoath great engine, as they intend to have a new boiler immediately, so as to prevent stopping to cleanse; and a boiler on this new plan can be made for one-third less expense than on the old plan, when you count the large boiler-house and ashes-pit, and brickwork round the boiler. It is not intended to alter any part of the engine or condenser, but only work with high steam from this new boiler; and if this boiler only performs as good duty as the old one, it will be a saving of near 300l. to them on the erection.The vast matter this great engine has in motion will answer in part the use of a fly-wheel: the whole of the matter in motion is near about 200 tons, at a velocity of about 160 feet a minute. This I know will not be sufficient; but it will be about equal to a fly-wheel of 20 feet diameter, 25 tons weight, twenty rounds per minute, if weight and velocity answer the same purpose."Since Monday, the 18th February, being Dolcoath account-day, both engines have been on trial, and are to be continued until the next account, 17th instant. The engines are kept onin the usual way, as at other times. Neither of the engines have done so much duty as on the first trials, as they have not been so strictly attended to. The average of the trial at this time stands 26 cwt. for a bushel of coals to Boulton and Watt's engine; mine, 83 cwt. for a bushel of coals."If I do not remain in Cornwall to attend next Dolcoath account, I shall be in town about the 15th instant, otherwise about the 20th instant. I shall call on you immediately on my arrival. In this time I should be glad to hear from you again. The Trinity business will answer exceedingly well; I have two engines ready for that purpose to put to work on my arrival in town."I am, Sir,"Your very humble servant,"Rd. Trevithick."P.S.—I would try the evaporation of water by both boilers, but Boulton and Watt's engine is so pressed with work, and being on the best part of the mine, they will not stop it a moment. A boiler of 8 feet diameter and 30 feet long will have as much fire-sides in the tube as there is now in Dolcoath great boiler. The fire-tube in this boiler would be 5 feet diameter, and a fire-place 6 feet long in it would be 30 feet of fire-bars. In the whim-engines I find that a fire-place 14 inches long and the tube 2 feet 3 inches diameter would, being forced, burn 1 bushel per hour. At this rate the great tube would burn near 12 bushels per hour, which is above the quantity that the great engine boiler can consume, now at work. Small tubes would have an advantage over large ones. Two boilers would not cost much more than one large one, and be much stronger."
"Camborne,March 4th, 1806.
"Mr. Giddy,
"Sir,—The day after I wrote to you the first letter, I received yours, and this day I have yours of the 1st instant.
"I am very much obliged to you for the figures you have sent me. I am convinced that thepressure of steam will not hold good as theory points it out, because on expanding it will get colder, and of course lose a part of its expansive force after the steam-valve shuts. I think there can be no risk in making this trial on Dolcoath great engine, as they intend to have a new boiler immediately, so as to prevent stopping to cleanse; and a boiler on this new plan can be made for one-third less expense than on the old plan, when you count the large boiler-house and ashes-pit, and brickwork round the boiler. It is not intended to alter any part of the engine or condenser, but only work with high steam from this new boiler; and if this boiler only performs as good duty as the old one, it will be a saving of near 300l. to them on the erection.The vast matter this great engine has in motion will answer in part the use of a fly-wheel: the whole of the matter in motion is near about 200 tons, at a velocity of about 160 feet a minute. This I know will not be sufficient; but it will be about equal to a fly-wheel of 20 feet diameter, 25 tons weight, twenty rounds per minute, if weight and velocity answer the same purpose.
"Since Monday, the 18th February, being Dolcoath account-day, both engines have been on trial, and are to be continued until the next account, 17th instant. The engines are kept onin the usual way, as at other times. Neither of the engines have done so much duty as on the first trials, as they have not been so strictly attended to. The average of the trial at this time stands 26 cwt. for a bushel of coals to Boulton and Watt's engine; mine, 83 cwt. for a bushel of coals.
"If I do not remain in Cornwall to attend next Dolcoath account, I shall be in town about the 15th instant, otherwise about the 20th instant. I shall call on you immediately on my arrival. In this time I should be glad to hear from you again. The Trinity business will answer exceedingly well; I have two engines ready for that purpose to put to work on my arrival in town.
"I am, Sir,"Your very humble servant,"Rd. Trevithick.
"P.S.—I would try the evaporation of water by both boilers, but Boulton and Watt's engine is so pressed with work, and being on the best part of the mine, they will not stop it a moment. A boiler of 8 feet diameter and 30 feet long will have as much fire-sides in the tube as there is now in Dolcoath great boiler. The fire-tube in this boiler would be 5 feet diameter, and a fire-place 6 feet long in it would be 30 feet of fire-bars. In the whim-engines I find that a fire-place 14 inches long and the tube 2 feet 3 inches diameter would, being forced, burn 1 bushel per hour. At this rate the great tube would burn near 12 bushels per hour, which is above the quantity that the great engine boiler can consume, now at work. Small tubes would have an advantage over large ones. Two boilers would not cost much more than one large one, and be much stronger."
The battle-ground of the fight between low and high pressure from 1806 to 1812 had also served for the personal encounter of Trevithick, sen., and Watt a quarter of a century before, when the Dolcoath great pumping engine was erected to compete with the twoearlier atmospherics; all three were still at work, overlooked by Carn Brea hill and castle, once the resort of Druid priests, whose sacrificial rites are still traced, by the hollows and channels for the blood of victims on the granite rocks.
Carn Brea CastleCarn Brea Castle.[W. J. Welch.]
Carn Brea Castle.[W. J. Welch.]
"Camborne,March 21st, 1806."Mr. Giddy,"Sir,—The trial between the two engines ended last Monday, which was Dolcoath day. Boulton and Watt's engine, per average of trial, 1 ton 20 cwt. 2 qrs., with 1 bushel of coals; the other, 5 tons 11 cwt. 3 qrs., with 1 ditto, the same depth of shaft. The adventurers ordered the new castings that were made for another of Boulton and Watt's engines to be thrown aside,and another new engine of mine to be built immediately. The great boiler for the old engine is not yet ordered."I have received orders for nine engines within these four weeks, all for Cornwall. Two 12-inch cylinders, two 16-inch ditto, three 9-inch ditto, one 8-inch ditto, one 7-inch ditto. I expect one will be put to work next week at Wheal Abraham, for lifting water."This day I shall leave Cornwall for London. Shall stop two days in the neighbourhood of Tavistock, and take orders for three engines. As soon as I arrive in town I will call at your lodgings. I expect that the patent will be brought into court about the end of May. A person in Wales owes us about 600l.patent premium, and he says that the patent is not good. More particulars you shall have on my arrival."The railroad is going forward. I have the drawings in hand for the inclined plane."I am, Sir,"Your very humble servant,"Rd. Trevithick.
"Camborne,March 21st, 1806.
"Mr. Giddy,
"Sir,—The trial between the two engines ended last Monday, which was Dolcoath day. Boulton and Watt's engine, per average of trial, 1 ton 20 cwt. 2 qrs., with 1 bushel of coals; the other, 5 tons 11 cwt. 3 qrs., with 1 ditto, the same depth of shaft. The adventurers ordered the new castings that were made for another of Boulton and Watt's engines to be thrown aside,and another new engine of mine to be built immediately. The great boiler for the old engine is not yet ordered.
"I have received orders for nine engines within these four weeks, all for Cornwall. Two 12-inch cylinders, two 16-inch ditto, three 9-inch ditto, one 8-inch ditto, one 7-inch ditto. I expect one will be put to work next week at Wheal Abraham, for lifting water.
"This day I shall leave Cornwall for London. Shall stop two days in the neighbourhood of Tavistock, and take orders for three engines. As soon as I arrive in town I will call at your lodgings. I expect that the patent will be brought into court about the end of May. A person in Wales owes us about 600l.patent premium, and he says that the patent is not good. More particulars you shall have on my arrival.
"The railroad is going forward. I have the drawings in hand for the inclined plane.
"I am, Sir,"Your very humble servant,"Rd. Trevithick.
The fact that expansion of steam caused reduction of heat was so evident to Trevithick that he ventured to doubt his friend's theory. The trials between the whim-engines having continued a fortnight, showed that the high-pressure steam-puffer had lifted 83 cwt., while the low-pressure steam vacuum only lifted 26 cwt. with the consumption of a bushel of coal. A suitable high-pressure boiler for the Watt low-pressure steam 63-inch pumping engine should be 30 feet long, 8 feet in diameter, with an internal fire-tube 5 feet in diameter; proportions approved of in the present day. The recommendation in 1806 to use small tubes may claim to be the first practical decision on the advantage of tubular boilers; and at the same time we read of the first hesitating step on the part of the public to use high-pressure steam in a Watt low-pressure engine,which was still deferred for further consideration, even with the limited pressure of 25 lbs. to an inch; so the large Watt pumping engines were doomed for another four or five years to struggle through their work with low-pressure steam, though at that time Cook's Kitchen high-pressure expansive condensing whim-engine had been for years at work close by.
The shareholders professed to have fear of explosion; but party-feeling and ignorance were the real causes of opposition, for working men had no dread of the new engines, while influential men leaned toward Watt's old-fashioned plans.
This fear of Trevithick's expansive plans and high steam is the more surprising, because at that time a new boiler was required for the Watt 63-inch cylinder pumping engine and Trevithick's cylindrical tubular boiler could be made for one-third less cost than the Watt waggon boiler, thus saving 300l., and in addition he promised to apply the higher pressure of steam to the Watt engine without any change in its parts or expenditure of money, and make it set in motion at the commencement of the stroke the 200 tons of pump-rods, the momentum of which would, with the expansion of the steam, when shutting it off soon after the first start in the movement of each stroke, carry it through to the end; and he practically compares this advantage from hoarded momentum in the pumping engine with his experience of the fly-wheel of the rolling-mill expansive engine in Wales.
The whim-engine with a fire-tube 2 feet 3 inches in diameter used 84 lbs. of coal per hour; and at that rate one cylindrical boiler 30 feet long, 8 feet in diameter, with internal fire-tube 5 feet in diameter, would supply steam for Watt's 63-inch cylinder; but in place of ithe preferred two smaller boilers, because small tubes have an advantage over large ones, and are much stronger.
The whim trials—high-pressure puffer against low-pressure vacuum—went on for another fortnight, when high pressure, having done twice as much work as low pressure, with an equal consumption of coal, the adventurers threw aside the work that had been made for another Watt engine, ordering one in its stead from Trevithick; but they could not just then make up their minds to place the Watt 63-inch pumping engine in his hands.
"Camborne,May 30th, 1806."Dear Sir,"I am very happy to find you have so far continued your agreement with the Trinity gents, and think the bargain is a good one. Must still beg leave to remind you not to proceed to show what your engine will do till the agreement is fully drawn up and regularly signed."Dolcoath agents, since they are informed of the accident at the iron-works in Wales,of the engine blowing to pieces, have requested me to have your opinion whether the old cylinder is strong enough for the boiler of the intended new engine, or whether you would recommend them to have a new one. Your answer to this as soon as possible, as Mr. Williams and some others are likely to make some objections."Mr. Sims, the engineer, has published in the Truro paper, that one of Boulton and Watt's engines at Wheal Jewell has drawn more than a ton of ore over and above that drawn by the Dolcoath engine from the same depth by a bushel of coal. On inquiry I found they had only tried for twenty-two hours. They said they left off with as good a fire as they began with. This I argued was not a fair trial. They say they are now on a trial for a month."The little engine at Wheal Abraham does its duty extremely well. The particulars as to consumption of coal cannot be fairly ascertained, as she has never been covered,is fed with cold water, and has not water to draw to keep her constantly at work."I wish I could give a better account of the mines than is in my power to give, or of the standard price for ore, though the latter is rather looking up than otherwise. Our friend, North Binner Downs, is better than paying cost, but very little. At present the levels are all poor; the lode in the west shaft has underlayed faster than the shaft, and we have not seen it for several fathoms. The ground lately in the shaft has been cleaner killas, and if any alteration, better ground. It is now 9 fathoms under the 55-fathom level, and we are driving to cut the lode. The ground in the cross-cut is harder than when you were on the spot. The water is sinking in old Binner; it is about 7 fathoms under the adit in the western part, and deeper in the eastern part; we do not account for this. Wheal St. Aubyn combined poor. Wheal Abraham looks promising, and Creuver about paying cost. Dolcoath is better than when you left us, or when I was in London. The last sale was only about 800 tons. The next sale on Thursday is upwards of 1100 tons, and we expect a little better standard."I wish you could discover who that old gent is that wanted a large slice in Dolcoath, that I might get at him through some unknown channel, for I want money sadly."Cook's Kitchen continues poor, Tin Croft ditto; Wheal Fanny not rich. We had a pretty little fight last account there with T. Kevill and W. Reynolds, Esquires: black eyes and bloody noses the worst effects. T. Kevill's face was much disfigured, and he might have found a new road out of his coat."At a meeting of Condurrow adventurers yesterday, twenty-four of them agreed to have one of our engines, cylinder 12 inches in diameter and 6-feet stroke, provided the Foxes do not object to it. When the order is given I shall write to Mr. Hazeldine, provided I do not hear from you that it is better to send the order to any other place."If you have occasion to write Mr. Hazeldine, I wish you would press him to hasten the engines for Wheal Goshen, &c."I am served with a Vice-warden's petition by Mr. Harrisfor not working the Weith mine in a more effectual manner, and he prays the Vice-warden to make the sett void. The trial will come on some time the beginning of July, and by that time I suppose we shall have two fire-engines working thereon."Had Mr. Harvey done as he was desired we should have had one working there at this time, but he has but now begun to do anything to it. We have the cylinder and ends home from Polgooth, and my cousin Simon Vivian is making the tubes. We have the other cylinder from Wheal Treasury, and I have ordered Horton to cast a cock for it the same as that at Dolcoath. We have cut the south lode at the adit level about 50 or 60 fathoms east of the engine, and have driven about 20 fathoms on it. It turns out about half a ton per fathom at 20l.a ton. The ground at 40s.per fathom; this all in a hole, and is better going down. The back is sett to four men at 3s.11d.; their time is out this week, and I suppose they must have 5s.next. This may turn out a few thousands, and I think too promising a thing to give up to Mr. Harris."I am happy to inform you that all our friends are in good health, and beg my most respectful compliments to Mrs. Rogers and adopted son; and am,"Dear, Sir,"Yours very sincerely,"Andw. Vivian."The promised news respecting the engine business I am very anxious to have, as it will I hope make meproud, as proud I shall be when I am able to pay everyone their demands, and have sufficient to carry on a little business to maintain my family and self without the assistance of others. May you succeed in your undertaking and also be independent, is the sincere wish of your friend. John Finnis and others are anxious to know when they will be wanted."A. V."
"Camborne,May 30th, 1806.
"Dear Sir,
"I am very happy to find you have so far continued your agreement with the Trinity gents, and think the bargain is a good one. Must still beg leave to remind you not to proceed to show what your engine will do till the agreement is fully drawn up and regularly signed.
"Dolcoath agents, since they are informed of the accident at the iron-works in Wales,of the engine blowing to pieces, have requested me to have your opinion whether the old cylinder is strong enough for the boiler of the intended new engine, or whether you would recommend them to have a new one. Your answer to this as soon as possible, as Mr. Williams and some others are likely to make some objections.
"Mr. Sims, the engineer, has published in the Truro paper, that one of Boulton and Watt's engines at Wheal Jewell has drawn more than a ton of ore over and above that drawn by the Dolcoath engine from the same depth by a bushel of coal. On inquiry I found they had only tried for twenty-two hours. They said they left off with as good a fire as they began with. This I argued was not a fair trial. They say they are now on a trial for a month.
"The little engine at Wheal Abraham does its duty extremely well. The particulars as to consumption of coal cannot be fairly ascertained, as she has never been covered,is fed with cold water, and has not water to draw to keep her constantly at work.
"I wish I could give a better account of the mines than is in my power to give, or of the standard price for ore, though the latter is rather looking up than otherwise. Our friend, North Binner Downs, is better than paying cost, but very little. At present the levels are all poor; the lode in the west shaft has underlayed faster than the shaft, and we have not seen it for several fathoms. The ground lately in the shaft has been cleaner killas, and if any alteration, better ground. It is now 9 fathoms under the 55-fathom level, and we are driving to cut the lode. The ground in the cross-cut is harder than when you were on the spot. The water is sinking in old Binner; it is about 7 fathoms under the adit in the western part, and deeper in the eastern part; we do not account for this. Wheal St. Aubyn combined poor. Wheal Abraham looks promising, and Creuver about paying cost. Dolcoath is better than when you left us, or when I was in London. The last sale was only about 800 tons. The next sale on Thursday is upwards of 1100 tons, and we expect a little better standard.
"I wish you could discover who that old gent is that wanted a large slice in Dolcoath, that I might get at him through some unknown channel, for I want money sadly.
"Cook's Kitchen continues poor, Tin Croft ditto; Wheal Fanny not rich. We had a pretty little fight last account there with T. Kevill and W. Reynolds, Esquires: black eyes and bloody noses the worst effects. T. Kevill's face was much disfigured, and he might have found a new road out of his coat.
"At a meeting of Condurrow adventurers yesterday, twenty-four of them agreed to have one of our engines, cylinder 12 inches in diameter and 6-feet stroke, provided the Foxes do not object to it. When the order is given I shall write to Mr. Hazeldine, provided I do not hear from you that it is better to send the order to any other place.
"If you have occasion to write Mr. Hazeldine, I wish you would press him to hasten the engines for Wheal Goshen, &c.
"I am served with a Vice-warden's petition by Mr. Harrisfor not working the Weith mine in a more effectual manner, and he prays the Vice-warden to make the sett void. The trial will come on some time the beginning of July, and by that time I suppose we shall have two fire-engines working thereon.
"Had Mr. Harvey done as he was desired we should have had one working there at this time, but he has but now begun to do anything to it. We have the cylinder and ends home from Polgooth, and my cousin Simon Vivian is making the tubes. We have the other cylinder from Wheal Treasury, and I have ordered Horton to cast a cock for it the same as that at Dolcoath. We have cut the south lode at the adit level about 50 or 60 fathoms east of the engine, and have driven about 20 fathoms on it. It turns out about half a ton per fathom at 20l.a ton. The ground at 40s.per fathom; this all in a hole, and is better going down. The back is sett to four men at 3s.11d.; their time is out this week, and I suppose they must have 5s.next. This may turn out a few thousands, and I think too promising a thing to give up to Mr. Harris.
"I am happy to inform you that all our friends are in good health, and beg my most respectful compliments to Mrs. Rogers and adopted son; and am,
"Dear, Sir,"Yours very sincerely,"Andw. Vivian.
"The promised news respecting the engine business I am very anxious to have, as it will I hope make meproud, as proud I shall be when I am able to pay everyone their demands, and have sufficient to carry on a little business to maintain my family and self without the assistance of others. May you succeed in your undertaking and also be independent, is the sincere wish of your friend. John Finnis and others are anxious to know when they will be wanted.
"A. V."
The explosion at Greenwich in 1803 was made much of, though the fault was clearly not in the boiler. Threeyears afterwards, in 1806, a steam-cylinder burst in Wales, therefore Mr. Williams, a large shareholder in Dolcoath, objected to the use of high-pressure expansive steam in their large Watt pumping engine, and desired their engineer, Mr. Sims, to make a competitive trial after his own fashion. At Condurrow Mine one of Trevithick's engines was to be ordered if the Foxes and Williamses did not object; and so it was that Trevithick's high-pressure steam-boiler was not ordered, and the Watt vacuum engine was for a longer time to receive no increase of power.
"Some of Captain Dick's early boilers had flattish or oval fire-tubes. In 1820 I repaired an old one in Wheal Clowance Mine in Gwinear. The flat top had come down a little; we put in a line of bolts, fastening the top of the tube to the outer casing."About 1818 I saw in Carsize Mine in Gwinear a pumping engine that Captain Dick had put up. The boiler was a cylinder of cast iron, with a wrought-iron tube going through its length in which the fire was placed. The steam-cylinder was vertical, fixed in the boiler. She had an air-pump and worked with a four-way cock. The steam was about 100 lbs. to the inch."[68]"About 1820 I removed one of Captain Trevithick's early high-pressure whim-engines from Creuver and Wheal Abraham, and put it as a pumping engine in Wheal Kitty, where it continued at work for about fifteen years. The boiler was of cast iron, in two lengths bolted together, about 6 feet in diameter and 10 feet long. At one end a piece was bolted, into which the cylinder was fixed, so that it had the steam and water around it. There was an internal wrought-iron tube that turned back again to the fire-door end, where the wrought-iron chimney was fixed; the fire-grate end of the tube was about 2 feet 6 inches in diameter, and tapered down to about 1 foot 6 inches at the chimney end. It was a puffer, working 60 lbs. of steamto the inch; it worked very well. There were several others in the county at that time something like it. It was made at the Neath Abbey Works in Wales."[69]
"Some of Captain Dick's early boilers had flattish or oval fire-tubes. In 1820 I repaired an old one in Wheal Clowance Mine in Gwinear. The flat top had come down a little; we put in a line of bolts, fastening the top of the tube to the outer casing.
"About 1818 I saw in Carsize Mine in Gwinear a pumping engine that Captain Dick had put up. The boiler was a cylinder of cast iron, with a wrought-iron tube going through its length in which the fire was placed. The steam-cylinder was vertical, fixed in the boiler. She had an air-pump and worked with a four-way cock. The steam was about 100 lbs. to the inch."[68]
"About 1820 I removed one of Captain Trevithick's early high-pressure whim-engines from Creuver and Wheal Abraham, and put it as a pumping engine in Wheal Kitty, where it continued at work for about fifteen years. The boiler was of cast iron, in two lengths bolted together, about 6 feet in diameter and 10 feet long. At one end a piece was bolted, into which the cylinder was fixed, so that it had the steam and water around it. There was an internal wrought-iron tube that turned back again to the fire-door end, where the wrought-iron chimney was fixed; the fire-grate end of the tube was about 2 feet 6 inches in diameter, and tapered down to about 1 foot 6 inches at the chimney end. It was a puffer, working 60 lbs. of steamto the inch; it worked very well. There were several others in the county at that time something like it. It was made at the Neath Abbey Works in Wales."[69]
These boilers were of the kind first tried in Cornwall about 1800. The oval tube in the Kensington model of 1798 continued in use in Cornwall for many years. The cast-iron outer casing was soon abandoned, though one of them in Wales remained in work fifty years, using steam of 60 lbs. to 100 lbs. to the inch.
"Hayle Foundry,August 26th, 1810."My dear Jane,,"I saw Captain Andrew Vivian on Wednesday, who told me that he had been offered 150l.a year to inspect all the engines in the county, and report what duty they were doing, in order to stimulate the engineers. He declined accepting it, having too much to do already; and he thought it would be worth Trevithick's notice, as it would not take him more than a day or two in a month."I remain, my dear Jane,"Yours sincerely,"H. Harvey.."I wrote this letter on Sunday, with an intention of sending it then, but thought it best to wait until this day, in hopes of hearing the determination of Government in your favour; but your letter has arrived without the desired information. All that I can now say is, to desire that Trevithick will make up his mind to return to Cornwall immediately."H. H."
"Hayle Foundry,August 26th, 1810.
"My dear Jane,,
"I saw Captain Andrew Vivian on Wednesday, who told me that he had been offered 150l.a year to inspect all the engines in the county, and report what duty they were doing, in order to stimulate the engineers. He declined accepting it, having too much to do already; and he thought it would be worth Trevithick's notice, as it would not take him more than a day or two in a month.
"I remain, my dear Jane,"Yours sincerely,"H. Harvey..
"I wrote this letter on Sunday, with an intention of sending it then, but thought it best to wait until this day, in hopes of hearing the determination of Government in your favour; but your letter has arrived without the desired information. All that I can now say is, to desire that Trevithick will make up his mind to return to Cornwall immediately.
"H. H."
The application to the Government for remuneration for benefits conferred on the public was unsuccessful. The office of registrar of Cornish engines was unsuitable; fortunately for mining interests, illness obliged Trevithick to revisit his native county, for by the increased power and economy of his engines Dolcoath Mine, sofrequently mentioned, and so important in olden time, now returns 70,000l.worth of tin yearly.
Trevithick's first act on returning to Cornwall in 1810 was the erection of the high-pressure boilers and pole vacuum engine at Wheal Prosper; at the same time renewing his proposals to Dolcoath to use his improved boilers, which had been broken off in 1806, and to apply high-pressure steam to their low-pressure Watt engine, with the same safety and profit as in Wheal Prosper; the evidence was undeniable, so his plans were agreed to, and in the early part of 1811 the high-pressure boilers, called the Trevithick or Cornish boilers, were constructed in the Dolcoath Mine under his directions.
Old John Bryant, who worked the Dolcoath large engines both before and after the introduction of higher pressure steam, including the Carloose or Bullan Garden 45-inch cylinder engine, Wheal Gons 63-inch cylinder single engine, and the Watt 63-inch cylinder double, with the bee-but boiler, such as Trevithick, sen., used in 1775,[70]followed by the Watt waggon boiler, and afterwards by the globular boiler of Trevithick, jun., in 1799,[71]and still later also with the cylindrical boiler of 1811, gave the following statement, when seventy-four years old, to the writer:—
"In the old bee-but and the waggon boiler the steam pressure in the boiler was not much; we did not trouble about it so long as the engines kept going: when the steam was too high it blew off through the feed-cistern. When Captain Trevithick tried his high steam in Dolcoath we hoisted up the feed-cistern as high as we could; when the steam got up, it blew the water out of the cistern. Captain Dick holloed out, 'Why don't you trig down the clack?'"The cylindrical boilers when they were first put in leakedvery much; we could hardly keep up the fire sometimes. I reckon the steam was 30 or 40 lbs. to the inch. Captain Dick's boilers made him lots of enemies. I heard say in one mine where he was trying his boilers against Boulton and Watt's waggon, a lot of gunpowder was put into the heap of coal."[72]
"In the old bee-but and the waggon boiler the steam pressure in the boiler was not much; we did not trouble about it so long as the engines kept going: when the steam was too high it blew off through the feed-cistern. When Captain Trevithick tried his high steam in Dolcoath we hoisted up the feed-cistern as high as we could; when the steam got up, it blew the water out of the cistern. Captain Dick holloed out, 'Why don't you trig down the clack?'
"The cylindrical boilers when they were first put in leakedvery much; we could hardly keep up the fire sometimes. I reckon the steam was 30 or 40 lbs. to the inch. Captain Dick's boilers made him lots of enemies. I heard say in one mine where he was trying his boilers against Boulton and Watt's waggon, a lot of gunpowder was put into the heap of coal."[72]
The waggon or hearse Watt boiler was attached to his 63-inch cylinder double, and the old man recollected having raised the water cistern, when Trevithick's globe boiler gave an increased pressure in 1799, ten or twelve years before the cylindrical boilers were made in Dolcoath.
"Some time after Captain Dick's globe boiler and steam-whims had been at work in Dolcoath, a letter came down from London, saying that he would save the mine 100l.a month if they would put in one of his new plan boilers."They were put in hand in the mine, and I worked about them; they were wrought-iron cylindrical boilers, about 20 feet long, and 5 or 6 feet in diameter; the fire-tube was about 3 feet in diameter; the fire returned around the outside in brick flues. Three boilers were put in side by side."When Captain Dick first tried them, he said to the men, Now mind, the fire-bars must never have more than six inches of coal on them; give a shovel or two to one boiler, and then to another. When Captain Dick's back was turned, the men said they wasn't going to do anything of the sort, there would never be no rest for them. They used to say that the boilers saved more than 170l. the first month."[73]
"Some time after Captain Dick's globe boiler and steam-whims had been at work in Dolcoath, a letter came down from London, saying that he would save the mine 100l.a month if they would put in one of his new plan boilers.
"They were put in hand in the mine, and I worked about them; they were wrought-iron cylindrical boilers, about 20 feet long, and 5 or 6 feet in diameter; the fire-tube was about 3 feet in diameter; the fire returned around the outside in brick flues. Three boilers were put in side by side.
"When Captain Dick first tried them, he said to the men, Now mind, the fire-bars must never have more than six inches of coal on them; give a shovel or two to one boiler, and then to another. When Captain Dick's back was turned, the men said they wasn't going to do anything of the sort, there would never be no rest for them. They used to say that the boilers saved more than 170l. the first month."[73]
Clark, when a boy, in 1799, helped to construct Trevithick's globular boiler in Dolcoath, and recollected the events of the few following years, during the contests with the whim-engines about 1806, and the introduction of the large cylindrical wrought-iron boilers for the pumping engines in 1811, and the struggle preceding the downfall of the Watt low-pressure steam vacuum engine, to make room for the high-pressure expansive steam-engine, with or without vacuum.
"About 1812 Captain Trevithick threw out the Boulton and Watt waggon boilers at Dolcoath and put in his own, known as Trevithick's boiler. They were about 30 feet long, 6 feet in diameter, with a tube about 3 feet 6 inches in diameter going through its length. There was a space of about 6 inches between the bottom of the tube and the outer casing. Many persons opposed the new plans. The Boulton and Watt low-pressure engine did not work well with the high steam, and the water rose in the mine workings. Captain Trevithick, seeing that he was being swamped, received permission from the mine managers to dismiss the old engine hands and employ his own staff. Captain Jacob Thomas was the man chosen to put things right. He never left the mine until the engine worked better than ever before, and forked the water to the bottom of the mine. Before that time the average duty in the county by the Boulton and Watt engines was seventeen or eighteen millions, and in two or three years, with Trevithick's boilers and improvements in the engines, the duty rose to forty millions. About 1826 he (Captain Vivian) was manager of Wheal Towan; their engines were considered the best in the county, doing eighty-seven millions; they had Trevithick's boilers, working with high-pressure steam and expansive gear; few if any of Boulton and Watt's boilers could then be found in the county. Sir John Rennie and other scientific men, who doubted the reports of the duty, came and made their own trials with the engines, and were satisfied that the duty was correctly reported."About that time a Mr. Neville requested him to report on the engines at his colliery at Llanelthy; one was an atmospheric of Newcomen's, doing six millions; and four or five of Boulton and Watt's patent engines averaged fourteen millions."[74]
"About 1812 Captain Trevithick threw out the Boulton and Watt waggon boilers at Dolcoath and put in his own, known as Trevithick's boiler. They were about 30 feet long, 6 feet in diameter, with a tube about 3 feet 6 inches in diameter going through its length. There was a space of about 6 inches between the bottom of the tube and the outer casing. Many persons opposed the new plans. The Boulton and Watt low-pressure engine did not work well with the high steam, and the water rose in the mine workings. Captain Trevithick, seeing that he was being swamped, received permission from the mine managers to dismiss the old engine hands and employ his own staff. Captain Jacob Thomas was the man chosen to put things right. He never left the mine until the engine worked better than ever before, and forked the water to the bottom of the mine. Before that time the average duty in the county by the Boulton and Watt engines was seventeen or eighteen millions, and in two or three years, with Trevithick's boilers and improvements in the engines, the duty rose to forty millions. About 1826 he (Captain Vivian) was manager of Wheal Towan; their engines were considered the best in the county, doing eighty-seven millions; they had Trevithick's boilers, working with high-pressure steam and expansive gear; few if any of Boulton and Watt's boilers could then be found in the county. Sir John Rennie and other scientific men, who doubted the reports of the duty, came and made their own trials with the engines, and were satisfied that the duty was correctly reported.
"About that time a Mr. Neville requested him to report on the engines at his colliery at Llanelthy; one was an atmospheric of Newcomen's, doing six millions; and four or five of Boulton and Watt's patent engines averaged fourteen millions."[74]
When at last the cylindrical high-pressure boiler was admitted, and men had been taught to fire them,many persons still liked the old plans, and among them the easy-going low-pressure enginemen. The consequence was that the Watt engines under their management refused the early doses of Trevithick's high steam, not easily digesting it, and their obstinacy nearly swamped Trevithick and his plans.
"When a little boy, about 1812, I frequently carried my father's dinner from Penponds to Dolcoath Mine. One day, not finding him in the engine-house, I sought him in the account-house, but not knowing him in a miner's working dress, refused to give him his dinner. William West then worked with him. I heard there was difficulty in making the new boilers and the old engine work well; engineers from other mines looked on from a distance, not liking the risk of explosion. People seemed to be against the new plans; some labourers worked with them."
"When a little boy, about 1812, I frequently carried my father's dinner from Penponds to Dolcoath Mine. One day, not finding him in the engine-house, I sought him in the account-house, but not knowing him in a miner's working dress, refused to give him his dinner. William West then worked with him. I heard there was difficulty in making the new boilers and the old engine work well; engineers from other mines looked on from a distance, not liking the risk of explosion. People seemed to be against the new plans; some labourers worked with them."
This narration—sixty years after the events—from Mr. Richard Trevithick, the eldest son of the engineer, shows that William West helped in applying high-pressure steam to the Watt low-pressure engine, and that but few sympathized with the innovators on old customs; but among them was Captain Jacob Thomas, who successfully fed the old engine with strong steam.
At that time the Watt engines in Cornwall had been doing seventeen or eighteen millions; Trevithick's new boilers increased their duty to forty millions.
"William Pooly[75]was working in Dolcoath before Captain Trevithick's new boilers were put in, and helped to put them in."The Shammal 45-inch engine was an open-top cylinder, with a chain to the segment-head wooden beam. So was the 63-inch cylinder Stray Park engine, then called Wheal Gons[76]in Dolcoath sett, and the Boulton and Watt 63-inch cylinder double-acting."There used to be great talking about different boilers; a boiler of Captain Trevithick's worked with higher steam than the others. Just before Captain Dick came back to the mine a Boulton and Watt hearse boiler had been repaired with a new bottom; it was never used. I and William Causan took a job to cut up the boiler at 1s.6d.the hundredweight; it weighed 17 tons. Jeffrie and Gribble were the mine engineers; Glanville used to be considered Captain Dick's man in the mine. You could stand upright on the fire-bars in the middle hollow of the hearse boiler, and so you could in the outside brick flues; the middle hollow was like a horse-shoe. When Captain Dick put in his cylindrical boilers he altered the 63-inch single; there was hardly anything of her left but the main wall, with the wood bob and a chain to the piston-rod, and also to the pump-rods. There was an air-pump, and I think a second-hand cylinder was brought, but it was a 63-inch; the old Shammal engine had been altered, too."The new boiler put in was about 8 feet in diameter and from 30 to 40 feet long, two round tubes went through it; the fire-place in one end of one tube and in the other end of the other tube; after going through the tubes the draught went into the brick flues under the bottom and sides. When the new engine was put in, Gribble said, ‘Why, these little things will never get steam enough;’ everybody said so."In the Boulton and Watt engines we didn't trouble about feed-pumps and gauge-cocks."A wire came through a stuffing box in the top of the boiler; a biggish stone in the boiler was fastened to one end of the wire, the other end was fastened to a weighted lever near the water cistern, just above the boiler; when the water got low the stone opened the valve in the water cistern. That was when they were putting in Captain Dick's new cylindrical boilers to the old 63-inch engine. She did so much more work, with less coal, that in a year or so they agreed to throw out Boulton and Watt's engine, and to put in a stronger one that could stand Captain Dick's high steam. Jeffrie and Gribble were the mineengineers that put her up. The 76-inch cylinder came from Wales. The big beam was cast at Perran Foundry in 1815; you can see the name and date upon it now. The boiler and the gear-work were made in the mine. The exhaust-valve is exactly as when it was put in, worked by a rack-and-tooth segment. The equilibrium valve is unchanged, except that the rack is taken out and a link put in."The steam-valve was taken out soon after she went to work, and the present double-beat valve was put in; it is the first of the kind I ever saw. Some were made before that time with a small valve on the top of the big one, that opened first, to ease the pressure."John West[77]fitted up the valve-gear in the mine with the expansive tappets, the same as when she stopped a month or two ago, and the same as the present new one has."Captain Dick's cutting off his strong steam at an early part of the stroke, used to make the steam-valve strike very hard; so the new plan valve, with a double beat, was put in; that must have been about 1816 or 1817; and the valve and expansive horn for working were just exactly like what they have put into the present new engine in 1869. She was the engine that showed them how to fork the water, and burn only half the coal."I worked in this mine the old atmospheric engines, and then Boulton and Watt; and then Trevithick's boilers in Boulton and Watt; and then Trevithick's boilers and engine; and now I come every day to the new engine, though I can't do much. They give me 35s.a month; and my name is William Pooly, Dolcoath, 1869."
"William Pooly[75]was working in Dolcoath before Captain Trevithick's new boilers were put in, and helped to put them in.
"The Shammal 45-inch engine was an open-top cylinder, with a chain to the segment-head wooden beam. So was the 63-inch cylinder Stray Park engine, then called Wheal Gons[76]in Dolcoath sett, and the Boulton and Watt 63-inch cylinder double-acting.
"There used to be great talking about different boilers; a boiler of Captain Trevithick's worked with higher steam than the others. Just before Captain Dick came back to the mine a Boulton and Watt hearse boiler had been repaired with a new bottom; it was never used. I and William Causan took a job to cut up the boiler at 1s.6d.the hundredweight; it weighed 17 tons. Jeffrie and Gribble were the mine engineers; Glanville used to be considered Captain Dick's man in the mine. You could stand upright on the fire-bars in the middle hollow of the hearse boiler, and so you could in the outside brick flues; the middle hollow was like a horse-shoe. When Captain Dick put in his cylindrical boilers he altered the 63-inch single; there was hardly anything of her left but the main wall, with the wood bob and a chain to the piston-rod, and also to the pump-rods. There was an air-pump, and I think a second-hand cylinder was brought, but it was a 63-inch; the old Shammal engine had been altered, too.
"The new boiler put in was about 8 feet in diameter and from 30 to 40 feet long, two round tubes went through it; the fire-place in one end of one tube and in the other end of the other tube; after going through the tubes the draught went into the brick flues under the bottom and sides. When the new engine was put in, Gribble said, ‘Why, these little things will never get steam enough;’ everybody said so.
"In the Boulton and Watt engines we didn't trouble about feed-pumps and gauge-cocks.
"A wire came through a stuffing box in the top of the boiler; a biggish stone in the boiler was fastened to one end of the wire, the other end was fastened to a weighted lever near the water cistern, just above the boiler; when the water got low the stone opened the valve in the water cistern. That was when they were putting in Captain Dick's new cylindrical boilers to the old 63-inch engine. She did so much more work, with less coal, that in a year or so they agreed to throw out Boulton and Watt's engine, and to put in a stronger one that could stand Captain Dick's high steam. Jeffrie and Gribble were the mineengineers that put her up. The 76-inch cylinder came from Wales. The big beam was cast at Perran Foundry in 1815; you can see the name and date upon it now. The boiler and the gear-work were made in the mine. The exhaust-valve is exactly as when it was put in, worked by a rack-and-tooth segment. The equilibrium valve is unchanged, except that the rack is taken out and a link put in.
"The steam-valve was taken out soon after she went to work, and the present double-beat valve was put in; it is the first of the kind I ever saw. Some were made before that time with a small valve on the top of the big one, that opened first, to ease the pressure.
"John West[77]fitted up the valve-gear in the mine with the expansive tappets, the same as when she stopped a month or two ago, and the same as the present new one has.
"Captain Dick's cutting off his strong steam at an early part of the stroke, used to make the steam-valve strike very hard; so the new plan valve, with a double beat, was put in; that must have been about 1816 or 1817; and the valve and expansive horn for working were just exactly like what they have put into the present new engine in 1869. She was the engine that showed them how to fork the water, and burn only half the coal.
"I worked in this mine the old atmospheric engines, and then Boulton and Watt; and then Trevithick's boilers in Boulton and Watt; and then Trevithick's boilers and engine; and now I come every day to the new engine, though I can't do much. They give me 35s.a month; and my name is William Pooly, Dolcoath, 1869."
Three years ago (in 1869), when the writer entered the old engine-house in which Watt's 63-inch cylinder double had been erected in 1780, adjoining the old walls that then enclosed that early Newcomen 45-inch cylinder Carloose engine, re-erected by Trevithick, sen., in 1775 in Bullan Garden portion of Dolcoath,an old man sat near a small window in a recess in the thick wall of the engine-house, within reach of the gear-handles of the Jeffrie and Gribble 76-inch cylinder engine that Trevithick, jun., had erected in 1816 on the foundations of the removed Watt engine; he held in one hand a portion of slate from the roof, and in the other an old pocket-knife, one-half of the blade of which had been broken off, leaving a jagged fracture, with which he made the figures of some calculation on the rude slate; on his nose rested the brass frame of a pair of very ancient spectacles, with horn glasses. He answered the writer's question by, "Yes, I am William Pooly; I worked this engine, and the other engines before it—the great double and the little Shammal working out of the same shaft; and I am seventy-four years of age. The 63 single worked upon a shaft up there; she was called Wheal Gons." That old man, still living, had worked in Dolcoath Mine one of the first steam-engines of Newcomen; the 45-inch, modified by Trevithick, sen.; then the 63-inch double of Watt; and, finally, the high-pressure engines of Trevithick, jun.; he saw the open-top cylinders, atmospheric of Newcomen, in the Shammal 45-inch and Wheal Gons 63-inch, with their wooden beams with segment-headed ends, moving in rivalry with the Watt 63-inch double, with cylinder-cover and parallel motion; he saw the two former engines, as altered by Trevithick, jun., using the higher steam from the globular boiler on which Henry Clark worked in 1799, when "there used to be great talking about different boilers, and a boiler of Captain Trevithick's worked with higher steam than the others; and the waggon boiler of Watt, that had just been repaired, was discarded and cut up;" thus described by Trevithick, "the fire-place is 22 feet from fire-door tofire-door, 9 feet wide, and 7 feet thick in fire,"[78]which he proposed to replace in 1806 by a cylindrical boiler to give steam of 25 lbs. on the inch.
Pooly also saw the finishing stroke in 1811, when the boilers still known as the Trevithick or Cornish boilers, gave steam to the three engines; after a twelve years' fight between low and high pressure, commencing with Trevithick's globular boiler and internal tube, in Dolcoath, in the year 1799, from which time it gained step by step, though in comparatively small engines, up to 1811, when the cylindrical boilers took the place of the condemned hearse and globular boilers, and gave really strong and expansive steam to the three Dolcoath pumping engines that from time immemorial had been rivals, causing all three of them to lift an increased quantity of water, and at the same time to save one-half in the cost of coal; this continued for four or five years, when in 1816 the 63-inch double and the 45-inch, being the youngest and the oldest of the three, were removed, that a new 76-inch cylinder, better adapted to Trevithick's expansive steam might more cheaply perform their joint work. Prior to this change the three engines were known by the names Shammal 45-inch, formerly Bullan Garden,[79]but before that as Carloose, of the period and form of the Pool engine;[80]Stray Park 63 single, formerly Wheal Gons,[81]dated from 1770 to 1777; and the 63-inch double of Watt in 1780.