"London,November 17th, 1827.""My dear Sir,"I arrived here from Liverpool last night, and this morning had the pleasure of receiving your kind letter of the 15th. The brig 'Bunker's Hill,' in which we came from Carthagena to New York, was wrecked within a few hours' sail of the port. We were in rather a disagreeable situation for some time, but more afraid than hurt. The cargo was nearly all lost. The ship was got off, but a complete wreck. The cause, however, of my delay in arriving arose from the want of the needful. You recollect Mr. Stephenson and Mr. Empson, agents for the Colombian Mining Association, whom we met at Carthagena. They kindly offered to supply me, but having determined to visit the celebrated Falls of Niagara, they insisted on my accompanying them, which I did."I am truly rejoiced to learn that your countrymen retain so lively a sense of the importance of your services. I think with you that before sounding the public or proceeding further, it might be well we should meet quietly to talk over everything and arrange our ideas, and that Cornwall, for the reasons you mention and others, would be the better place."The boys are well, and desire their respects to you."Your sincere friend,"J. M. Gerard."Capt. Trevithick."
"London,November 17th, 1827.
""My dear Sir,
"I arrived here from Liverpool last night, and this morning had the pleasure of receiving your kind letter of the 15th. The brig 'Bunker's Hill,' in which we came from Carthagena to New York, was wrecked within a few hours' sail of the port. We were in rather a disagreeable situation for some time, but more afraid than hurt. The cargo was nearly all lost. The ship was got off, but a complete wreck. The cause, however, of my delay in arriving arose from the want of the needful. You recollect Mr. Stephenson and Mr. Empson, agents for the Colombian Mining Association, whom we met at Carthagena. They kindly offered to supply me, but having determined to visit the celebrated Falls of Niagara, they insisted on my accompanying them, which I did.
"I am truly rejoiced to learn that your countrymen retain so lively a sense of the importance of your services. I think with you that before sounding the public or proceeding further, it might be well we should meet quietly to talk over everything and arrange our ideas, and that Cornwall, for the reasons you mention and others, would be the better place.
"The boys are well, and desire their respects to you.
"Your sincere friend,"J. M. Gerard.
"Capt. Trevithick."
Trevithick was friendly with George Stephenson when, in 1805, he nursed little Bobby. Twenty yearsafterwards, when George had comprehended Trevithick's locomotive, and desired his son's return to England to assist him in making it useful, Robert Stephenson, grown to manhood, met his father's friend in the wilds of Central America, both of them having been engaged in mining operations, and both on their return to England. George Stephenson's son made for himself a fortune and a name, his friend earned poverty and neglect. These two men, though well known to the engineering world, had no mutual attraction, and in their native land remained strangers to each other.
"42, St. Mary Axe,January 13th, 1828.""My dear Sir,"I had very unexpectedly a letter from Costa Rica this morning by the way of Jamaica, including two for you, which I have the pleasure of transmitting. Mine is from Montelegre, begun on the 25th of August, and finished on the 11th of September, when Don Antonio Pinto, with some people from the Alajuela, was to start by the road of Sarapique on his way to Jamaica. His intention was to find a better route as far as Buona Vista, after which he would probably nearly follow our course to the Embarcadero of Gamboa."Whether he succeeded in finding a less rugged road to Buona Vista I do not know. That he reached his destination seems clear from our letters having come to hand; but from their old date it would appear that he had either met with difficulties on the road or with considerable detention at San Juan. Montelegre writes me that Don Yonge had effected a compromise on your account with the Castros. Gamboa got back to San José on the 18th August, twelve days after he parted from us, to the great joy of our mutual friends. Mr. Paynter had been unwell after our departure. Both he and Montelegre desire their kindest recollections to you"Yours most sincerely,"J. M. Gerard."Capt. Trevithick."
"42, St. Mary Axe,January 13th, 1828.
""My dear Sir,
"I had very unexpectedly a letter from Costa Rica this morning by the way of Jamaica, including two for you, which I have the pleasure of transmitting. Mine is from Montelegre, begun on the 25th of August, and finished on the 11th of September, when Don Antonio Pinto, with some people from the Alajuela, was to start by the road of Sarapique on his way to Jamaica. His intention was to find a better route as far as Buona Vista, after which he would probably nearly follow our course to the Embarcadero of Gamboa.
"Whether he succeeded in finding a less rugged road to Buona Vista I do not know. That he reached his destination seems clear from our letters having come to hand; but from their old date it would appear that he had either met with difficulties on the road or with considerable detention at San Juan. Montelegre writes me that Don Yonge had effected a compromise on your account with the Castros. Gamboa got back to San José on the 18th August, twelve days after he parted from us, to the great joy of our mutual friends. Mr. Paynter had been unwell after our departure. Both he and Montelegre desire their kindest recollections to you
"Yours most sincerely,"J. M. Gerard.
"Capt. Trevithick."
The newly-discovered track taken by the homeward bound over the Cordilleras soon brought Don Antonio Pinto and others into the field in search of passable roads to the Atlantic. Twelve days required by Gamboa to effect his return to San José, a distance of perhaps sixty miles, indicate the difficulty.
Mr. Gerard passed some weeks with Trevithick in Cornwall arranging the best means of getting together a company to work on a large scale the Costa Rica mines.
"Hayle Foundry,January 24th, 1828.""Dear Sir,"Yesterday I saw Mr. M. Williams, who informed me that he should leave Cornwall for London on next Thursday week, and requested that I would accompany him. If you think it absolutely necessary that I should be in town at the same time, I would attend to everything that would promote the mining interest. When I met the Messrs. Williams on the mining concerns some time since, they mentioned the same as you now mention of sending some one out with me to inspect the mines, and that they would pay me my expenses and also satisfy me for my trouble with any sum that I would mention, because such proceedings would be satisfactory to all who might be connected in this concern. I objected to this proposal on the ground that a great deal of time would be lost and that the circumstances of your contracts in San José would not admit of such a detention; for that reason alone was my objection grounded, and if that objection could have been removed I should have been very glad to have the mines inspected by any able person chosen for that purpose, because it would not only take off the responsibility from us, but also strengthen our reports, as the mining prospects there will bear it out, and that far beyond our report. Some time since I informed you that I had drawn on the company for 100l.to pay 70l.passage-money, and would have left 30l.to defray my expenses returning to London. The time for payment is up, but I have not as yet heard anything about it, therefore I expect there must be an omission by the bankers whose hands it was to have passedthrough for tendering it for payment. Perhaps in a day or two I shall hear something about it; I would thank you to inform me should you know anything about it. The unfavourable result of the gun I attribute in a great measure to the change in the Ministry and my not being present to explain the practicability of making the machinery about it simple. When Lord Cochrane has seen it, and a meeting takes place with him, my return to London may again revive its merits. This unfavourable report does not lessen its merits, neither will it deter me from again moving forward to convince the public of its practicability. I shall make immediately a portable model of the iron ship and engine, as they will be applicable to packets, which have been attempted at Falmouth, but found that the consumption of coals was so great that the whole of the ships' burthen would not contain sufficient coals to take them to Lisbon and return again, and on that account it was discontinued. That insurmountable object will now be totally removed, and I think that Lord Cochrane will make a very excellent tool to remove many weak objections made by persons not having sufficient ability to judge for themselves. His Lordship, being a complete master of science, is capable of appreciating their value from theory and from practice. I should not be surprised to see him down here to inspect it. It will be very agreeable if his Lordship comes here at the same time as yourself; he is a remarkably pleasant companion. My hearty thanks for your mother's good wishes towards me."Your humble servant,"Rd. Trevithick."Mr. Jno. Gerard,"No. 42, St. Mary Axe, London."
"Hayle Foundry,January 24th, 1828.
""Dear Sir,
"Yesterday I saw Mr. M. Williams, who informed me that he should leave Cornwall for London on next Thursday week, and requested that I would accompany him. If you think it absolutely necessary that I should be in town at the same time, I would attend to everything that would promote the mining interest. When I met the Messrs. Williams on the mining concerns some time since, they mentioned the same as you now mention of sending some one out with me to inspect the mines, and that they would pay me my expenses and also satisfy me for my trouble with any sum that I would mention, because such proceedings would be satisfactory to all who might be connected in this concern. I objected to this proposal on the ground that a great deal of time would be lost and that the circumstances of your contracts in San José would not admit of such a detention; for that reason alone was my objection grounded, and if that objection could have been removed I should have been very glad to have the mines inspected by any able person chosen for that purpose, because it would not only take off the responsibility from us, but also strengthen our reports, as the mining prospects there will bear it out, and that far beyond our report. Some time since I informed you that I had drawn on the company for 100l.to pay 70l.passage-money, and would have left 30l.to defray my expenses returning to London. The time for payment is up, but I have not as yet heard anything about it, therefore I expect there must be an omission by the bankers whose hands it was to have passedthrough for tendering it for payment. Perhaps in a day or two I shall hear something about it; I would thank you to inform me should you know anything about it. The unfavourable result of the gun I attribute in a great measure to the change in the Ministry and my not being present to explain the practicability of making the machinery about it simple. When Lord Cochrane has seen it, and a meeting takes place with him, my return to London may again revive its merits. This unfavourable report does not lessen its merits, neither will it deter me from again moving forward to convince the public of its practicability. I shall make immediately a portable model of the iron ship and engine, as they will be applicable to packets, which have been attempted at Falmouth, but found that the consumption of coals was so great that the whole of the ships' burthen would not contain sufficient coals to take them to Lisbon and return again, and on that account it was discontinued. That insurmountable object will now be totally removed, and I think that Lord Cochrane will make a very excellent tool to remove many weak objections made by persons not having sufficient ability to judge for themselves. His Lordship, being a complete master of science, is capable of appreciating their value from theory and from practice. I should not be surprised to see him down here to inspect it. It will be very agreeable if his Lordship comes here at the same time as yourself; he is a remarkably pleasant companion. My hearty thanks for your mother's good wishes towards me.
"Your humble servant,"Rd. Trevithick.
"Mr. Jno. Gerard,"No. 42, St. Mary Axe, London."
Gerard and Trevithick believed in the great value of the Costa Rica mines, and in the feasibility of working them profitably could capital sufficient be obtained. After a year or two passed in fruitless attempts to form a mining company in England, Mr. Gerard visited Holland and France with no better success; and while on this mission died in poverty in Paris, though broughtup in youth as the expectant inheritor of family estates in Scotland. One of his letters says:—
"Robert Stephenson has given us his experience that it was unwise to take many English miners or workers to such countries. The chief reliance must after all be placed on the native inhabitants, under the direction and training of a small but well-selected party of Englishmen."Mining operations in that country are of such recent origin that a mining population can scarcely be said to exist. English workmen are not so manageable even in this country, and much less so in Spanish America, where they are apt to be spoiled by the simplicity and excessive indulgence even of the better classes, and where the high salaries they receive place them far above the country people of the same condition. All this tends to presumption and intolerance on their part, and ultimately to disputes and irreconcilable disgusts between them and the natives."
"Robert Stephenson has given us his experience that it was unwise to take many English miners or workers to such countries. The chief reliance must after all be placed on the native inhabitants, under the direction and training of a small but well-selected party of Englishmen.
"Mining operations in that country are of such recent origin that a mining population can scarcely be said to exist. English workmen are not so manageable even in this country, and much less so in Spanish America, where they are apt to be spoiled by the simplicity and excessive indulgence even of the better classes, and where the high salaries they receive place them far above the country people of the same condition. All this tends to presumption and intolerance on their part, and ultimately to disputes and irreconcilable disgusts between them and the natives."
Mr. Michael Williams, Mr. Gibson, Mr. Macqueen, and others, were anxious to take up the mining scheme. The former proposed to send a person to examine the mines. This was a safe course, but not convenient to those who had made engagements to return without loss of time with miners and material to Costa Rica.
Mr. M. Williams informed the writer's brother that at a meeting of several gentlemen in London, a cheque for 8000l.was offered to Trevithick for his mining grant of the copper mountain in South America. Words waxed warm, and the proffered money was refused. The next day Mr. Williams said to him, "Why did you not pocket the cheque before you quarrelled with them?" Trevithick replied, "I would rather kick them down stairs!"
In the end Trevithick got nothing for either his South American mines or those in Costa Rica.
GUN-CARRIAGE—IRON SHIPS—HYDRAULIC CRANE—ICE MAKING—DRAINAGE OF HOLLAND—CHAIN-PUMP—OPEN-TOP CYLINDER—HAYLE HARBOUR—PATENT RIGHTS—PETITION TO PARLIAMENT.
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 Gun-carriage and Friction SlidesTrevithick's Gun-carriage and Friction Slides, 1827.
Trevithick's Gun-carriage and Friction Slides, 1827.
"Richard Trevithick, of the parish of Saint Erth, in the county of Cornwall, civil engineer, maketh oath and saith that he hath invented new methods for centering ordnance on pivots, facilitating the discharge of the same, and reducing manual labour in time of action. That he is the true inventor thereof, and that the same hath not been practised by any other person or persons whomsoever to his knowledge or belief."Sworn, 10th November, 1827, before me, Rd. Edmonds.""This gun is worked by machinery balanced on pivots giving it universal motion, by one man, with the facility of a soldier's musket. On one side a man puts in a copper charge of powder; on the opposite side a man drops a ball in a bag down the gun, as it stands muzzle up. The gunner, who sits on the seat behind the gun, points it and pulls the trigger. The firing causes it to run up an inclined plane at an angle of 25° for the purpose of breaking the recoil; it runs down again with its muzzle at the port, requiring no wadding, swabbing, cartridge, or ramming, but runs in, out, primes, cocks, shuts the pan, and breaks the recoil of itself; and by three men can be fired three times in a minute with accuracy. The gun-carriage is a tube 3 feet long and 3 feet diameter, made of wrought-iron plate 1/4 of an inch thick, centered on a pivot to the deck, with the gunner's seat attached, from which he looks through the case. As the gun requires no tackle, and but a man on each side to work it, only a space of 5 feet 6 inches is required from centre to centre of ports, therefore a single-deck ship will carry a greater number of guns than are now carried on a double-deckship, be worked with one-third of the hands, and be fired five times as fast as at present. A frigate would mount fifty 42-pound guns on one deck, with 150 men, and would discharge in the same time a greater weight of ball with greater precision than five 74-gun ships."[135]
"Richard Trevithick, of the parish of Saint Erth, in the county of Cornwall, civil engineer, maketh oath and saith that he hath invented new methods for centering ordnance on pivots, facilitating the discharge of the same, and reducing manual labour in time of action. That he is the true inventor thereof, and that the same hath not been practised by any other person or persons whomsoever to his knowledge or belief.
"Sworn, 10th November, 1827, before me, Rd. Edmonds."
"This gun is worked by machinery balanced on pivots giving it universal motion, by one man, with the facility of a soldier's musket. On one side a man puts in a copper charge of powder; on the opposite side a man drops a ball in a bag down the gun, as it stands muzzle up. The gunner, who sits on the seat behind the gun, points it and pulls the trigger. The firing causes it to run up an inclined plane at an angle of 25° for the purpose of breaking the recoil; it runs down again with its muzzle at the port, requiring no wadding, swabbing, cartridge, or ramming, but runs in, out, primes, cocks, shuts the pan, and breaks the recoil of itself; and by three men can be fired three times in a minute with accuracy. The gun-carriage is a tube 3 feet long and 3 feet diameter, made of wrought-iron plate 1/4 of an inch thick, centered on a pivot to the deck, with the gunner's seat attached, from which he looks through the case. As the gun requires no tackle, and but a man on each side to work it, only a space of 5 feet 6 inches is required from centre to centre of ports, therefore a single-deck ship will carry a greater number of guns than are now carried on a double-deckship, be worked with one-third of the hands, and be fired five times as fast as at present. A frigate would mount fifty 42-pound guns on one deck, with 150 men, and would discharge in the same time a greater weight of ball with greater precision than five 74-gun ships."[135]
"Hayle, Cornwall,21st February, 1828."My Lord Cochrane,[136]"With great pleasure I read in the papers the announcement of your arrival again in England, and am much gratified to find a person of your superior natural and practical talents, so rare to be obtained, to whom I may communicate my views."I have proposed to Government to build an iron ship, and a gun on a new principle, which are to undergo an investigation, and have lodged a drawing of the ship and a model of the gun with my friend Mr. Gerard, a gentleman who returned with me from America, and who will present to you this letter with the above-mentioned drawing and model."I have had an iron boat made for the purpose of sending it to London, to show the method of constructing ships on this plan, roomy, strong, and cheap. Also a wrought-iron ship with a steam-engine on an improved principle, which in a few days will be laid on the stocks at the Hayle Foundry iron manufactory."
"Hayle, Cornwall,21st February, 1828.
"My Lord Cochrane,[136]
"With great pleasure I read in the papers the announcement of your arrival again in England, and am much gratified to find a person of your superior natural and practical talents, so rare to be obtained, to whom I may communicate my views.
"I have proposed to Government to build an iron ship, and a gun on a new principle, which are to undergo an investigation, and have lodged a drawing of the ship and a model of the gun with my friend Mr. Gerard, a gentleman who returned with me from America, and who will present to you this letter with the above-mentioned drawing and model.
"I have had an iron boat made for the purpose of sending it to London, to show the method of constructing ships on this plan, roomy, strong, and cheap. Also a wrought-iron ship with a steam-engine on an improved principle, which in a few days will be laid on the stocks at the Hayle Foundry iron manufactory."
Though Lord Cochrane was just the person to be interested in such schemes, it does not appear that he took any part in them. At that time he was at work on his own particular ideas for marine propulsion.
"London,February, 1828.""My dear Sir,"Immediately after the receipt of your last, which I only received after twelve o'clock on the 7th, I went to the Ordnance Office, where, though Colonel Gossett was no longer an official personage, I had the good luck to meet him. He told me that the model of the gun was at Woolwich, and could not be got at in time to stop the progress of the other patent, and which he considered of but little moment, as he thought it very unlikely there could be any collision between the two inventions. He likewise said that from the official changes that had taken place in the office, much loss of time might be incurred by recalling the model, which was in train of being examined. To-day I have received a letter addressed to youfrom the Ordnance, by which it appears that your model has passed through an unsuccessful ordeal before the special committee.
"London,February, 1828.
""My dear Sir,
"Immediately after the receipt of your last, which I only received after twelve o'clock on the 7th, I went to the Ordnance Office, where, though Colonel Gossett was no longer an official personage, I had the good luck to meet him. He told me that the model of the gun was at Woolwich, and could not be got at in time to stop the progress of the other patent, and which he considered of but little moment, as he thought it very unlikely there could be any collision between the two inventions. He likewise said that from the official changes that had taken place in the office, much loss of time might be incurred by recalling the model, which was in train of being examined. To-day I have received a letter addressed to youfrom the Ordnance, by which it appears that your model has passed through an unsuccessful ordeal before the special committee.
"'Office of Ordnance,21st February, 1828."Sir,"'I am directed by the Master General to acquaint you that the Select Committee of Artillery Officers, to whom your model of a 42-pounder carronade and carriage on a new principle were referred, have reported that on examination of the invention, they consider it to be wholly inapplicable to practical purposes. Your model is at the Ordnance Office, and will be delivered on your sending for it."'I am, Sir,"'Your most obedient humble servant,"'Lowndes."'R. Trevithick, Esq.'
"'Office of Ordnance,21st February, 1828.
"Sir,
"'I am directed by the Master General to acquaint you that the Select Committee of Artillery Officers, to whom your model of a 42-pounder carronade and carriage on a new principle were referred, have reported that on examination of the invention, they consider it to be wholly inapplicable to practical purposes. Your model is at the Ordnance Office, and will be delivered on your sending for it.
"'I am, Sir,"'Your most obedient humble servant,"'Lowndes.
"'R. Trevithick, Esq.'
"My poor mother, who I regret to say has been very delicate ever since your departure, and is now again confined to bed, desires me to say that she is very sorry she is not Master General of the Ordnance, to give it a fairpracticaltrial, as she thinks Captain Trevithick's opinions, though she cannot pronounce his name, may be fairly placed in opposition to that of the special committee of artillery officers."Ever faithfully yours,"J. M. Gerard."
"My poor mother, who I regret to say has been very delicate ever since your departure, and is now again confined to bed, desires me to say that she is very sorry she is not Master General of the Ordnance, to give it a fairpracticaltrial, as she thinks Captain Trevithick's opinions, though she cannot pronounce his name, may be fairly placed in opposition to that of the special committee of artillery officers.
"Ever faithfully yours,"J. M. Gerard."
The recoil gun-carriage was his first occupation after twelve years of travel in countries where mechanical appliances were less thought of than weapons of war. He commenced this, his second era of inventions, with what he called a new thing, though it was but an extension of his schemes of 1809, when he patented iron vessels, hollow sliding masts and yards, self-reefing sails, and sliding keels.
The model gun was of brass, resting on a railway formed of two inclined bars of iron, up which the recoilpropelled it into a convenient position for cleaning and loading. Its own gravity caused it to fall into the required place for being again fired. The slides also served as friction-bars to regulate the recoil.
The gun and the slides carrying it were enclosed in a wrought-iron box, having openings in the front and rear for the passage of the muzzle and the breech. The muzzle front of the box was pivoted to the deck by a strong bolt as a centre of motion, whilst its rear was supported on two small wheels resting on the deck, allowing the gun to change its line of horizontal fire by sweeping from the centre pivot. The gunner's seat moved with the carriage, from which he could elevate or depress the muzzle by a lever. The gun was self-priming and self-cocking; the powder charge was enclosed in a copper case. Captain Moncrieff's patent gun-carriage of the present day is described in words somewhat like those used by Trevithick forty years before. "The recoil lifted a weight smoothly and without friction; the gun and the weight were held in the position arrived at by a catch until the gun was loaded and ready to fire again."[137]
The iron boat mentioned in his note to Lord Cochrane as being made at Hayle, was "for the purpose of sending to London to show the method of constructing ships on this plan, roomy, strong, and cheap," and was thus spoken of in a newspaper of the 26th April, 1829. "The 'Scotsman' alludes to the intended construction of iron steamboats at Glasgow by Mr. Neilson:—"For fear of the public being misled on this subject, we beg to state that so far back as last Christmas twelvemonths we saw Trevithick, of Cornwall, superintending the construction of an iron man-of-war launch, with theavowed intention of applying a similar principle of construction to the building of fast-sailing iron steamboats." This intimation, in 1829, to the since famous Glasgow iron-ship builders, that they could not claim the invention because Trevithick had made such a boat in 1827, was probably in ignorance of Trevithick's patent and models of 1809,[138]explaining the advantages of ships of iron, either under sail or under steam, for commerce or for fighting-ships. The improved high-pressure steam-engine then in hand for iron ships was but the perfecting of his plans of twenty years before.[139]
"Lauderdale House, Highgate,April 19th, 1830.""Mr. Gilbert,"Sir,—I find by looking into the 'Art of Gunnery' that a 42-lb. shot discharged at the rate of 2000 feet a second in vacuum would send it to the height of 63,360 feet, which multiplied by the weight of the shot would be 2,661,120 lbs., with 12 lbs. of powder; and as guns, after being heated to about the heat of boiling water, will recoil their usual distance with half their first charge of powder, it proves that one-half the powder at first is lost in heating the gun to about 212°, which is a great deal under the heat of fired powder, therefore only 6 lbs. of powder effective force is applied to the ball. Now suppose this 6 lbs. of powder to be one quarter part carbon, 1½ lb. is all the heat that can possibly be applied to perform this duty; then 1 lb. of carbon would be equal to 1,774,080 lbs. of duty actually performed; but if you take into calculation the great loss of power by the powder not being instantly all set on fire, with the gun so much below the heat of fired powder, the windage by the sides of the shot, the ball flying from the powder, and the immense power remaining in the gun at the time of the ball leaving its muzzle; if this was applied expansively, as in a cylinder, it may fairly be said to have double this power, or 3,548,160 lbs. for 1 lb. of carbon consumed, which, multiplied by 84, being the pounds in 1 bushelof carbon, gives 300 millions of duty. If it was applied to the best advantage, say on a piston, calling powder one thousand atmospheres, it would far exceed that duty. A gun 9 feet long and 7-inch bore has 16 feet of cold sides, and condenses at first one-half of its force by its cold sides and loses 150 millions in a 200th part of a second, while the ball passes from the breech to the muzzle. This gives 221,760 lbs. condensed by each foot of surface sides in so short a time. Binner Downs cylinder was taken as condensing 2500 lbs. for each surface foot in six seconds; therefore, without taking into account the great difference in time, there is eighty-eight times as much power lost by each foot of cold sides of the gun as by the cylinder sides. This shows what a considerable power is lost by cold sides where the vapour is so rare. Boulton and Watt's engine, doing twenty millions, performs with 1 lb. of coal a duty of 240,000 lbs., or about 1/14th part of what is done by 1 lb. of carbon in powder. The water evaporated by the boiler is 7 lbs. thrown into steam by 1 lb. of coal, and a duty of 33,750 lbs. for each pound of water evaporated."Suppose 1 lb. of powder to contain 12 oz. of nitre and 4 oz. of carbon, and 1/24th part of the nitre to be a fixed water, which would be half an ounce of water in every pound of powder, making the carbon eight times as much as the water; from this data 1 lb. of water in powder would perform a duty of 28,385,280 lbs.lbs.1 lb. of carbon in powder3,548,16014 times the consumption by the engine.1 lb. of coal in Boulton and Watt's engine240,0001 foot of cold sides of the gun221,76088 times as much loss by the cold sides of the gun1 foot of cold sides of the cylinder33,7501 lb. of coal for 7 lbs. of water in steam"14 times as much coal for water into steam as for water in powder.1 lb. of carbon for 8 oz. of water in powder""By this it appears that heat is loaded with fourteen times as much water in steam-engines as in powder, and does only 1/14th part of the duty of the water in powder. It is possible to heat steam independent of water, because if we work with steam of ten atmospheres, it would have ten times the capacity for heat, being in proportion to its gravity. The boiler standing onits end, with the fire in the bottom, and the water 1 foot thick above it, with a great number of small tubes from bottom to top, having great surface sides to heat the steam above the water, by working with a low chimney and slow fire, the tubes in the steam part of the boiler would not exceed 600° or 700° of heat, which would not injure them; as less water would be generated into steam, a very small part of the boiler would be sufficient for it; and as the coal required would be less, the boiler required would be very small. I state the foregoing to remind you that but little is yet known of what heat may be capable of performing; as this data so far exceeds whatever has been calculated on the power of heat before, when compared with steam in an engine."The power is sure, if we can find how to conduct it."I remain, Sir,"Your humble servant,"Richard. Trevithick."If you can spare time please to write to me."
"Lauderdale House, Highgate,April 19th, 1830.
""Mr. Gilbert,
"Sir,—I find by looking into the 'Art of Gunnery' that a 42-lb. shot discharged at the rate of 2000 feet a second in vacuum would send it to the height of 63,360 feet, which multiplied by the weight of the shot would be 2,661,120 lbs., with 12 lbs. of powder; and as guns, after being heated to about the heat of boiling water, will recoil their usual distance with half their first charge of powder, it proves that one-half the powder at first is lost in heating the gun to about 212°, which is a great deal under the heat of fired powder, therefore only 6 lbs. of powder effective force is applied to the ball. Now suppose this 6 lbs. of powder to be one quarter part carbon, 1½ lb. is all the heat that can possibly be applied to perform this duty; then 1 lb. of carbon would be equal to 1,774,080 lbs. of duty actually performed; but if you take into calculation the great loss of power by the powder not being instantly all set on fire, with the gun so much below the heat of fired powder, the windage by the sides of the shot, the ball flying from the powder, and the immense power remaining in the gun at the time of the ball leaving its muzzle; if this was applied expansively, as in a cylinder, it may fairly be said to have double this power, or 3,548,160 lbs. for 1 lb. of carbon consumed, which, multiplied by 84, being the pounds in 1 bushelof carbon, gives 300 millions of duty. If it was applied to the best advantage, say on a piston, calling powder one thousand atmospheres, it would far exceed that duty. A gun 9 feet long and 7-inch bore has 16 feet of cold sides, and condenses at first one-half of its force by its cold sides and loses 150 millions in a 200th part of a second, while the ball passes from the breech to the muzzle. This gives 221,760 lbs. condensed by each foot of surface sides in so short a time. Binner Downs cylinder was taken as condensing 2500 lbs. for each surface foot in six seconds; therefore, without taking into account the great difference in time, there is eighty-eight times as much power lost by each foot of cold sides of the gun as by the cylinder sides. This shows what a considerable power is lost by cold sides where the vapour is so rare. Boulton and Watt's engine, doing twenty millions, performs with 1 lb. of coal a duty of 240,000 lbs., or about 1/14th part of what is done by 1 lb. of carbon in powder. The water evaporated by the boiler is 7 lbs. thrown into steam by 1 lb. of coal, and a duty of 33,750 lbs. for each pound of water evaporated.
"Suppose 1 lb. of powder to contain 12 oz. of nitre and 4 oz. of carbon, and 1/24th part of the nitre to be a fixed water, which would be half an ounce of water in every pound of powder, making the carbon eight times as much as the water; from this data 1 lb. of water in powder would perform a duty of 28,385,280 lbs.
"By this it appears that heat is loaded with fourteen times as much water in steam-engines as in powder, and does only 1/14th part of the duty of the water in powder. It is possible to heat steam independent of water, because if we work with steam of ten atmospheres, it would have ten times the capacity for heat, being in proportion to its gravity. The boiler standing onits end, with the fire in the bottom, and the water 1 foot thick above it, with a great number of small tubes from bottom to top, having great surface sides to heat the steam above the water, by working with a low chimney and slow fire, the tubes in the steam part of the boiler would not exceed 600° or 700° of heat, which would not injure them; as less water would be generated into steam, a very small part of the boiler would be sufficient for it; and as the coal required would be less, the boiler required would be very small. I state the foregoing to remind you that but little is yet known of what heat may be capable of performing; as this data so far exceeds whatever has been calculated on the power of heat before, when compared with steam in an engine.
"The power is sure, if we can find how to conduct it.
"I remain, Sir,"Your humble servant,"Richard. Trevithick.
"If you can spare time please to write to me."
The foregoing may be classed either under cannon or steam-engine;Trevithickcombined them under the general laws of expansion by heat. Three years had passed since the committee of artillery officers sitting on his gun had given a verdict of no go; yet the subject was not forgotten, and his calculations enabled him to discover the explosive force, and the speed of the projectile in different parts of the gun, things which are now ascertained by mechanical tests and measures.
If a 7-inch cannon 9 feet long loses by absorption of heat during the time of the passage of the shot to the muzzle one-half of the expansive force of the powder, it is time to wrap our guns as well as our steam-engines in non-conductors. The greater heat of exploded powder than of steam caused eighty-eight times the amount of loss from abstracted heat, and yet the forcefrom a pound of carbon in powder, was fourteen times as much as the Watt engine gave from a pound of coal.
"London, No. 42, St. Mary Axe,June 18th, 1828.""Mr. Giddy,"Sir,—A few days since a Mr. Linthorn called on me and requested me to accompany him to Cable Street, near the Brunswick Theatre, to see a crane worked by the atmosphere, in a double-acting engine attached to it. He has a patent, and has entered into a contract with the St. Katharine's Dock Company to work their cranes, 140 in number, by a steam-engine of sufficient power to command the whole of them, by placing air-pipes around the docks, with a branch to each crane. To each crane is fixed a 10-inch cylinder, 20-inch stroke, double-acting. The atmosphere pressing on the piston like steam, the air is drawn from the pipes by a large air-pump and steam-engine."On being requested to give my opinion on this plan, after seeing one crane worked, I informed them of the disappointment that the ironmaster, Mr. Wilkinson, in Shropshire, several years since experienced, on the resistance of air in passing through long pipes from his blast-engine to his furnaces. He said he was aware of that circumstance, and it had since been further proved in London by one of the gas companies attempting to force gas a considerable distance, and who also failed."He thought that forcing an elastic fluid, and drawing it by a vacuum, were very different things, and that the error was removed by drawing in place of forcing. For my part I am not convinced on this head; but am still of opinion that the result on trial will be found nearly the same. However, let that be as it may, the expense and complication of the machine, having a double engine, with its gear attached to every separate crane, together with the immense quantity of air thrown into the air-pump from 140 double engines of 10 inches diameter, 20-inch stroke, eighty strokes per minute, and considering the numerous air leaks in such an extent of pipes and machines, must reduce the effect of the pressure of the atmosphere on each piston to a comparatively small power, unless the air-pump and steam-engine are beyond all reasonable bounds."Those objections I made them acquainted with, and saidthat, before they went to such an expense, it would be a safer plan to first make further inquiry, so that their first experiment might be on a sure plan, for the other dock companies were looking for the results of this experiment."At the time I was informed of this plan, a thought struck me that it might be accomplished by another mode preferable to this: by a steam-engine to force water in pipes round the dock, to say 30 or 40 lbs. to the inch, more or less, and to have a worm-shaft, working in a worm-wheel, the same as a common roasting-jack, and apply to the worm-shaft a spouting arm like Barker's mill; the worm-shaft standing perpendicular would work the worm-wheel fixed in the chain-barrel shaft of the crane."This would make a very simple and cheap machine, and produce a circular motion at once, instead of a piston alternating motion to drive a rotary motion. My report had some weight with them; inquiry is to be made into the plan proposed by me, so as to remunerate me, provided my plan is considered good. Mr. Linthorn wishes an investigation before scientific and able judges, and requested me to name some one. I must again make free in asking the favour of your advice (which you have so ably given me for thirty years) on this plan. Mr. Linthorn intends to request Dr. Wollaston to accompany you, any day convenient to you. In the meantime, should you see him, it might not be amiss to mention it to him; and should you be able to attend for an hour or two to this business, I would thank you to drop me a note, saying when it may be convenient. There is a memorandum of an agreement between Mr. Linthorn and me; but the plan I suggest is only at present made public to him and yourself."Your most obedient servant,"Richard. Trevithick.
"London, No. 42, St. Mary Axe,June 18th, 1828.
""Mr. Giddy,
"Sir,—A few days since a Mr. Linthorn called on me and requested me to accompany him to Cable Street, near the Brunswick Theatre, to see a crane worked by the atmosphere, in a double-acting engine attached to it. He has a patent, and has entered into a contract with the St. Katharine's Dock Company to work their cranes, 140 in number, by a steam-engine of sufficient power to command the whole of them, by placing air-pipes around the docks, with a branch to each crane. To each crane is fixed a 10-inch cylinder, 20-inch stroke, double-acting. The atmosphere pressing on the piston like steam, the air is drawn from the pipes by a large air-pump and steam-engine.
"On being requested to give my opinion on this plan, after seeing one crane worked, I informed them of the disappointment that the ironmaster, Mr. Wilkinson, in Shropshire, several years since experienced, on the resistance of air in passing through long pipes from his blast-engine to his furnaces. He said he was aware of that circumstance, and it had since been further proved in London by one of the gas companies attempting to force gas a considerable distance, and who also failed.
"He thought that forcing an elastic fluid, and drawing it by a vacuum, were very different things, and that the error was removed by drawing in place of forcing. For my part I am not convinced on this head; but am still of opinion that the result on trial will be found nearly the same. However, let that be as it may, the expense and complication of the machine, having a double engine, with its gear attached to every separate crane, together with the immense quantity of air thrown into the air-pump from 140 double engines of 10 inches diameter, 20-inch stroke, eighty strokes per minute, and considering the numerous air leaks in such an extent of pipes and machines, must reduce the effect of the pressure of the atmosphere on each piston to a comparatively small power, unless the air-pump and steam-engine are beyond all reasonable bounds.
"Those objections I made them acquainted with, and saidthat, before they went to such an expense, it would be a safer plan to first make further inquiry, so that their first experiment might be on a sure plan, for the other dock companies were looking for the results of this experiment.
"At the time I was informed of this plan, a thought struck me that it might be accomplished by another mode preferable to this: by a steam-engine to force water in pipes round the dock, to say 30 or 40 lbs. to the inch, more or less, and to have a worm-shaft, working in a worm-wheel, the same as a common roasting-jack, and apply to the worm-shaft a spouting arm like Barker's mill; the worm-shaft standing perpendicular would work the worm-wheel fixed in the chain-barrel shaft of the crane.
"This would make a very simple and cheap machine, and produce a circular motion at once, instead of a piston alternating motion to drive a rotary motion. My report had some weight with them; inquiry is to be made into the plan proposed by me, so as to remunerate me, provided my plan is considered good. Mr. Linthorn wishes an investigation before scientific and able judges, and requested me to name some one. I must again make free in asking the favour of your advice (which you have so ably given me for thirty years) on this plan. Mr. Linthorn intends to request Dr. Wollaston to accompany you, any day convenient to you. In the meantime, should you see him, it might not be amiss to mention it to him; and should you be able to attend for an hour or two to this business, I would thank you to drop me a note, saying when it may be convenient. There is a memorandum of an agreement between Mr. Linthorn and me; but the plan I suggest is only at present made public to him and yourself.
"Your most obedient servant,"Richard. Trevithick.
The reduction of friction by the use of an air-vacuum engine for working cranes, as designed by Mr. Linthorn, in lieu of an air-pressure engine, was doubted by Trevithick.
The Mont Cenis pneumatic-pressure machines which the writer saw at work lost much power by frictionbefore experience had taught remedies. The pneumatic vacuum tubes which propelled the trains on the South Devon Railway, failed to give the power that was expected. Sir William Armstrong's hydraulic cranes, brought into use not many years after the date of Trevithick's letter, have been found effective. The writer, not knowing that Trevithick had before recommended hydraulic cranes for warehouses, accompanied Sir William over his works, then being erected near Newcastle-on-Tyne, and talked with him on the detail of his crane designs.
Trevithick thought of giving circular motion to the crane chain-barrel by the attachment of a screw-propeller, acted on by the force of a current of water at a pressure of 30 or 40 lbs. to the inch. Sir William Armstrong's arrangement was quite different; the merit due to Trevithick was for having pointed out the suitability of water as a means of conveying power through warehouses where fire was inadmissible.
"London, 42, St. Mary Axe,June 29th, 1828.""Mr. Gilbert,"Sir,—Fancy and whim still prompt me to trouble you, and perhaps may continue to do until I exhaust your patience. A few days since I was in company where a person said that 100,000l.a year was paid for ice, the greatest part of which was brought by ships sent on purpose to the Greenland seas. A thought struck me at the moment that artificial cold might be made very cheap by the power of steam-engines; by compressing air in a condenser surrounded by water, and an injection to the same, so as to instantly cool down the highly-compressed air to the temperature of the surrounding air, and then admitting it to escape into liquid. This would reduce the temperature to any state of cold required."I remain, Sir,"Your very humble servant,"Richard. Trevithick.
"London, 42, St. Mary Axe,June 29th, 1828.
""Mr. Gilbert,
"Sir,—Fancy and whim still prompt me to trouble you, and perhaps may continue to do until I exhaust your patience. A few days since I was in company where a person said that 100,000l.a year was paid for ice, the greatest part of which was brought by ships sent on purpose to the Greenland seas. A thought struck me at the moment that artificial cold might be made very cheap by the power of steam-engines; by compressing air in a condenser surrounded by water, and an injection to the same, so as to instantly cool down the highly-compressed air to the temperature of the surrounding air, and then admitting it to escape into liquid. This would reduce the temperature to any state of cold required.
"I remain, Sir,"Your very humble servant,"Richard. Trevithick.
Trevithick's ideas for making ice have since been patented and made useful, though the detail of the operation has been improved by experience.
The Dutch, extending the use of steam on the Rhine and also in sea-going ships, wished Trevithick to see what was going on in Holland, where his nephew, Mr. Nicholas Harvey, was actively engaged in engineering. He had not money enough for the journey, and borrowed 2l.from a neighbour and relative, Mr. John Tyack. During his walk home a begging man said to him, "Please your honour, my pig is dead; help a poor man." Trevithick gave him 5s.out of the 40s.he had just begged for himself. How he managed to reach Holland his family never knew; but on his return he related the honour done him by the King at sundry interviews, and the kindness of men of influence in friendly communion and feasting.
"London,July 31st, 1828.""Mr. Gilbert,"Sir,—The night before last I arrived from Holland, where I spent ten days. I found my relative there, Mr. Nicholas Harvey, the son of John and Nancy Harvey. He is the engineer to the Steam Navigation Company at Rotterdam. They have a ship 235 feet long, 1500 tons burthen, with three 50-inch cylinders double, also two other vessels 150 feet long, each with two 50-inch cylinders double, ready to take troops to Batavia. The large ship with three engines cost 80,000l.The Steam Navigation Company built them, and many others of different sizes. This company has been anxious to get me to Holland, having heard of the duty performed by the Cornish engines. They were anxious to know what might be done towards draining and relieving Holland from its ruinous state."Immediately on arrival I joined the Dutch company, and entered into bonds with them."I give you, as near as I can, the present state of the country. About 250 years since, a strong wind threw a bank of sandacross the mouth of the river Rhine, which made it overflow its banks; 80,000 lives were lost, and about 40,000 acres of land, which remain to this time under 12 feet of water."About 100 years since the head and surface of the river Rhine was 5 feet below what it now is. The under floors of houses in Holland are nearly useless, and in another century must be totally lost, unless something is done to prevent it. The river at present is nearly overflowing its banks. In consequence of the rise of water, the windmill engines cannot lift it out. To erect steam-engines, they never could believe would repay the expense. Nearly one-half of Holland is at present under water, either totally or partially, because the ground kept dry in winter is flooded in summer."About six years since it was in contemplation to recover the 40,000 acres before mentioned, and a company was formed of the King and the principal men in Holland, to drain this by windmills, which they estimated would cost 250,000l., and making the banks and canals 450,000l.more, when made by men's labour, and seven years to accomplish it."This seven years was a great objection, because of the unhealthy state of the country while draining. The water is about 18 inches every year, to be lifted on an average 10 feet high. I have been furnished with correct calculations and drawings from this company."They expected to have drained 40,000 acres in seven years, at a cost of 700,000l., which, when drained, would have sold at 50l.per acre, about two millions."I find, from the statement given me, of 18 inches of water to be lifted 10 feet high, it would require about one bushel of coal to lift the water from one acre of ground for one year, and that a 63-inch cylinder double would perform the work of 40,000 acres, when working with high steam and condensing, at an expense of less than 3000l.per year. Engines in boats would cut and make the embankments and canals, without the help of men. I proposed six cylinders of 60 inches diameter, double power, which would drain the water in one year; and also four others for cutting the canals and making embankments. The expense would not exceed 100,000l.and one year, instead of700,000l.and seven years. Above 60,000 acres more are to be drained."It was also proposed by Government to cut open the river Rhine to 1000 yards wide and 6 feet deep for 50 or 60 miles in length; they supposed it would cost them ten millions sterling. I proposed to make iron ships of 1000 tons burthen, with an engine in each, which would load them, propel, and also empty them for about 1d.per ton. Each ton will be about a square yard, and the cutting the river Rhine 1000 yards wide, 6 feet deep, 50 or 60 miles in length, will not cost one and a half million, and be accomplished in a short time. I further proposed that all this rubbish be carried into the sea of the Zuyder Zee, which would make dry, by embanking with the rubbish, nearly 1,000,000 acres of good land, capable of paying ten times the sum of cutting open the river Rhine."All this would add 100 per cent. more to the surface of Holland, and at this time it is much wanted, because their settlements abroad are free almost of the mother-country, and they have too many inhabitants for the land at present. I made them plans for carrying the whole into effect, and have closed my agreement with them."In a few days I shall go to Cornwall, and promised to return again to Holland within a month. I saw Mr. Hall and the engineer of the Dock Company to-day. They are satisfied that the plan for working the cranes is a good one. I am to see them again on Monday next; after which I shall return home, where I hope to see you, to consult you on the best plan for constructing the machines for lifting the water, cutting the canals, and making the dykes."I remain, Sir,"Your very obedient servant,"Richard. Trevithick.
"London,July 31st, 1828.
""Mr. Gilbert,
"Sir,—The night before last I arrived from Holland, where I spent ten days. I found my relative there, Mr. Nicholas Harvey, the son of John and Nancy Harvey. He is the engineer to the Steam Navigation Company at Rotterdam. They have a ship 235 feet long, 1500 tons burthen, with three 50-inch cylinders double, also two other vessels 150 feet long, each with two 50-inch cylinders double, ready to take troops to Batavia. The large ship with three engines cost 80,000l.The Steam Navigation Company built them, and many others of different sizes. This company has been anxious to get me to Holland, having heard of the duty performed by the Cornish engines. They were anxious to know what might be done towards draining and relieving Holland from its ruinous state.
"Immediately on arrival I joined the Dutch company, and entered into bonds with them.
"I give you, as near as I can, the present state of the country. About 250 years since, a strong wind threw a bank of sandacross the mouth of the river Rhine, which made it overflow its banks; 80,000 lives were lost, and about 40,000 acres of land, which remain to this time under 12 feet of water.
"About 100 years since the head and surface of the river Rhine was 5 feet below what it now is. The under floors of houses in Holland are nearly useless, and in another century must be totally lost, unless something is done to prevent it. The river at present is nearly overflowing its banks. In consequence of the rise of water, the windmill engines cannot lift it out. To erect steam-engines, they never could believe would repay the expense. Nearly one-half of Holland is at present under water, either totally or partially, because the ground kept dry in winter is flooded in summer.
"About six years since it was in contemplation to recover the 40,000 acres before mentioned, and a company was formed of the King and the principal men in Holland, to drain this by windmills, which they estimated would cost 250,000l., and making the banks and canals 450,000l.more, when made by men's labour, and seven years to accomplish it.
"This seven years was a great objection, because of the unhealthy state of the country while draining. The water is about 18 inches every year, to be lifted on an average 10 feet high. I have been furnished with correct calculations and drawings from this company.
"They expected to have drained 40,000 acres in seven years, at a cost of 700,000l., which, when drained, would have sold at 50l.per acre, about two millions.
"I find, from the statement given me, of 18 inches of water to be lifted 10 feet high, it would require about one bushel of coal to lift the water from one acre of ground for one year, and that a 63-inch cylinder double would perform the work of 40,000 acres, when working with high steam and condensing, at an expense of less than 3000l.per year. Engines in boats would cut and make the embankments and canals, without the help of men. I proposed six cylinders of 60 inches diameter, double power, which would drain the water in one year; and also four others for cutting the canals and making embankments. The expense would not exceed 100,000l.and one year, instead of700,000l.and seven years. Above 60,000 acres more are to be drained.
"It was also proposed by Government to cut open the river Rhine to 1000 yards wide and 6 feet deep for 50 or 60 miles in length; they supposed it would cost them ten millions sterling. I proposed to make iron ships of 1000 tons burthen, with an engine in each, which would load them, propel, and also empty them for about 1d.per ton. Each ton will be about a square yard, and the cutting the river Rhine 1000 yards wide, 6 feet deep, 50 or 60 miles in length, will not cost one and a half million, and be accomplished in a short time. I further proposed that all this rubbish be carried into the sea of the Zuyder Zee, which would make dry, by embanking with the rubbish, nearly 1,000,000 acres of good land, capable of paying ten times the sum of cutting open the river Rhine.
"All this would add 100 per cent. more to the surface of Holland, and at this time it is much wanted, because their settlements abroad are free almost of the mother-country, and they have too many inhabitants for the land at present. I made them plans for carrying the whole into effect, and have closed my agreement with them.
"In a few days I shall go to Cornwall, and promised to return again to Holland within a month. I saw Mr. Hall and the engineer of the Dock Company to-day. They are satisfied that the plan for working the cranes is a good one. I am to see them again on Monday next; after which I shall return home, where I hope to see you, to consult you on the best plan for constructing the machines for lifting the water, cutting the canals, and making the dykes.
"I remain, Sir,"Your very obedient servant,"Richard. Trevithick.
In this mere outline of a life it is impossible to go fully into the merit of Trevithick's plans for doubling the land surface of Holland. A drainage company was formed in London with a board of directors, some ofwhom thought that a new kind of engine should be invented and patented as a means of excluding others from carrying on similar but competing operations. Trevithick, always ready to invent new things, though never forgetting his experience with old things, instinctively returned to the Dolcoath engines, and recommended them as suitable for the pumping work; but finally a new design was determined on, and Harvey and Co., of Hayle, received orders for the construction, with the greatest possible dispatch, of a pumping engine for Holland.
This happening shortly after the writer had been taken from the Bodmin school, he was desired to help in the erection of this engine, and after working-hours made a drawing of its original form.
Plate XV.a, iron barge;b, wood frame supporting pump;c, open-top steam-cylinder 3 feet diameter, 8-feet stroke;d, piston guide-wheel;e, connecting rod;f, fly-wheel;g, cranked axle working air-pump bucket;h, connecting rod for air-pump bucket;i, air-pump;j, condenser;k, steam and exhaust nozzles;l, eccentrics working steam and exhaust valves;m, steam-pipe;n, cylindrical boiler, with internal fire-tube;o, external brick flues;p, chimney;q, feed-pump;r, feed-pipe;s, cup or rag-wheel;t, rag-chain, with iron balls;u, pump-barrel, 3 feet diameter;v, wheel guiding balls into bottom of pump-barrel;w, launder.
PLATE 15PLATE 15TREVITHICK'S CHAIN AND BALL PUMP.London: E. & F. N. Spon, 48, Charing Cross Kell Bros. Lith London
PLATE 15TREVITHICK'S CHAIN AND BALL PUMP.
London: E. & F. N. Spon, 48, Charing Cross Kell Bros. Lith London
After a few successful though noisy trials, an alteration was made in the endless chain and in the guide-roller near the pump bottom. An amount of slack in the chain caused the balls to knock on passing this roller before entering the pump bottom. A chain having long links or bars of iron of uniform length, from ballto ball, jointed together by cross-pins, was substituted for the short link chain, and passed over a revolving hollow square frame at the bottom of the pump, in place of the curved roller-guide in the drawing. Each of the four sides of this square hollow frame was of the same length as the jointed link, and the balls lay in the hollow of the frame without touching it, contact being only on the links. The balls were thus guided directly into the bottom of the pump on their upward course with a rigid chain, and the swing and knocking was avoided. This pump was in principle the traditional rag-and-chain pump of a hundred years before; yet no trace of its use is met with during Trevithick's life in Cornwall. The early pump had rag balls, in keeping with the mechanical ignorance of the time, and suitable to man's power.
Trevithick's pump with iron balls raised "7200 gallons of water 10 feet high in a minute with 1½ lb. of coal,"[140]retaining all the original simplicity of the earlier rag-pump, having uniform circular motion and constant stream, without the use of a single valve. The engine and pump are thus described by him:—
"The first engine that will be finished here for Holland will be a 36-inch cylinder and a 36-inch water-pump, to lift water about 8 feet high. On the crank-shaft there is a rag-head of 8 feet diameter, going 8 feet per second, with balls of 3 feet diameter passing through the water-pump, which will lift about 100 tons of water per minute. It is in an iron boat, 14 feet wide, 25 feet long, 6 feet high, so as to be portable and pass from one spot to another without loss of time. This will drain 18 inches deep of water (the annual produce on the surface of each acre of land) in about twenty minutes; to drain each acre with about a bushel of coal costing 6d.per year. The engine is high pressure and condensing."[141]
"The first engine that will be finished here for Holland will be a 36-inch cylinder and a 36-inch water-pump, to lift water about 8 feet high. On the crank-shaft there is a rag-head of 8 feet diameter, going 8 feet per second, with balls of 3 feet diameter passing through the water-pump, which will lift about 100 tons of water per minute. It is in an iron boat, 14 feet wide, 25 feet long, 6 feet high, so as to be portable and pass from one spot to another without loss of time. This will drain 18 inches deep of water (the annual produce on the surface of each acre of land) in about twenty minutes; to drain each acre with about a bushel of coal costing 6d.per year. The engine is high pressure and condensing."[141]
It was something like the Newcomen open-topped cylinder of a hundred years before, but with a heavy piston, on the top of which a guide-wheel equal in diameter to the cylinder turned on a pin, to which the main connecting rod was jointed. The guide-wheel prevented any tendency to twist the piston from the angular positions of the connecting rod, and allowed the crank-shaft to be brought comparatively near to the cylinder top. The boiler was cylindrical, of wrought iron, with internal fire-tube and external brick flues; and gave steam of about 40 lbs. on the inch above the atmosphere, which, acting under the piston, caused the up-stroke, an expansive valve reducing the average pressure in the cylinder by one-half. The down-stroke was made by the atmospheric pressure of 14 lbs. on the inch, on the piston, its lower side being in vacuum, together with the weight of the thick piston and connecting rod, and the momentum of the revolving parts.
My readers must not suppose that this was an attempt to revive the discarded Newcomen engine; the likeness was only apparent; its power was mainly from the use of strong expansive steam, giving motion in the up-stroke through a rigid connecting rod, with controlling and equalizing crank and fly-wheel. It was not, as the Newcomen,[142]dependent for its power on the atmospheric pressure; and having no cylinder cover, or parallel motion, or beam, was not a Watt engine, though it had the Watt air-pump and condenser.
The Dolcoath engines continued to work with open-topped cylinders a quarter of a century after the Watt patent; and when they had passed away, many of Trevithick's high-pressure steam-engines retained the same form of outline, but had neither cylinder covers,parallel motion, air-pump, nor vacuum. The agricultural engines of 1813[143]and the South American engines of 1816[144]had neither cylinder cover nor any other part of the Watt engine, yet they successfully competed with it in power, economy, and usefulness.
This design reveals a stumbling-block that superficial people fall over. The boiler in the boat was surrounded by brick flues, while a life-long claim of Trevithick's is that before his tubular boiler with internal fire, there could not be a successful steamboat, because brick flues were dangerous in sea-going vessels, but in an iron boat in smooth water it answered its purpose without in any respect falsifying Trevithick's former claims or plans.
The chain pumping machine was in an iron barge, the 36-inch diameter pump fixed just outside the bow, its lower end a foot in the water; its height of 8 or 9 feet enabled the water from the pump-head to flow through launders over the banks of the lakes to be drained. Some of the directors came to Hayle to see it work, and were well pleased at the constant stream of water rushing from the foaming pump-head into the launders. The large size of the rag-wheel gave the rapidly revolving chain and balls a great speed. In passing through the pump each ball forced upwards the water above it, and drew up after it the following water; before any ball had passed out at the top of the pump the following ball had entered its bottom. The directors having desired the writer to take the engine to Holland and set it to work with the least possible delay, adjourned for refreshment before starting for London. In those few minutes differences arose, resulting in the engine remaining for months in the barge, and then going to the scrap heap.
Years afterwards others acted on Trevithick's drainage ideas, and Harvey and Co. built Cornish pumping engines with steam-cylinders 112 inches in diameter, similar in principle to the Dolcoath engine[145]of 1816, which effectually drained the Haarlem lake.
The Rhine during 100 years, in its passage through the low flat lands, had by deposit raised the level of its waters 5 feet, threatening to overflow the embankments and drown the surrounding country, that to a large extent was at a lower level than the river. All drainage from such land had to be pumped over the river bank, in many places 10 feet above the cultivated surface. Windmills had been used as pumping power, and a company had contemplated laying out 700,000l.in windmills and canals for drainage.
If the surface water averaged 18 inches in depth yearly, Trevithick could by steam-engines drain an acre of land by the consumption of a bushel of coal yearly. Four engines with cylinder of 63 inches in diameter would drain 160,000 acres, and four smaller engines in barges with suitable apparatus were to cut canals and construct embankments. The deposit of a hundred years was also to be removed, and the Rhine deepened 6 feet for a breadth of 1000 yards, and a length of 50 or 60 miles, by steam-dredgers, as used twenty years before in deepening the Thames,[146]to be fixed in iron ships of a thousand tons burthen. The cost of dredging from the bed of the river into a barge would be 1d.per ton; but this would be more than repaid by making with it an embankment, enclosing the Zuyder Zee, which would then in its turn be drained and made pasture land.
Before leaving for America he had reported on the best means of improving St. Ives Bay.[147]Hayle Harbourwas a branch of it, and he now suggested to Mr. Henry Harvey methods for deepening and improving it. A rival company of merchants and engineers, known then as Sandys, Carne, and Vivian, after many fights had recourse to law on the question of the course of a stream which had been changed by alterations during the making of wharfs and channels for ships.
Trevithick made a model in wood, movable layers of which indicated changes of level caused by workmen at different periods, giving a different course to the river bed. Mr. Harvey's counsel, since known as Lord Abinger and Sir William Follett, complimented Trevithick on the facility of understanding the case by reference to the model. The writer having carried the surveying chain, was present at the trial at the Bodmin assizes in 1829.