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CHAPTER VIII. PATENT OF 1802, AND LONDON LOCOMOTIVE.
Trevithick and Vivian's Specification.
"Our improvements in the construction and application of steam-engines are exhibited in the drawings hereunto annexed and explained, namely:—
In Plate IV., Figure 1 represents the vertical section of a steam-engine with the said improvements; and Figure 2 represents another vertical section of the same engine at right angles to the plane of Figure 1.
The dark shaded parts represent iron, and the red parts represent brickwork, and the yellow parts engine brass, excepting only the wooden supporters of the great frame in Figures 4 and 5, and the carriage-wheels in 6 and 7.
A represents the boiler made of a round figure, to bear the expansive action of strong steam. The boiler is fixed in a case D, luted inside with fire-clay, the lower part of which constitutes the fire-place 13, and the upper cavity affords a space round the boiler, in which the flame or heated vapour circulates round till it comes to the chimney E. The case D and the chimney are fixed upon a platform F, the case being supported upon four legs. C represents the cylinder enclosed for the most part in the boiler, having its nozzle, steam-pipe, and bottom cast all in one piece, in order to resist the strong steam, and with sockets in which the iron uprights of the external frame are firmly fixed. G represents a cock for conducting the steam, as may be more clearly seen by observing Figure 3, which is a plan of the top of the cylinder, and the same parts in Figure 2.
Figures 2 and 3, b represents the passage from the boiler to the cock G. This passage has a throttle-valve or shut, adjustable by the handle m, Figure 2, so as to withdraw the steam, and suffer the supply to be quicker or slower. The position of the cock represented in Figure 3 by the yellow circle is such, that the communication from the boiler through b, by a channel in the cock, is made good to d, which denotes the upper space of the cylinder above the piston, at the same time that the steam-pipe a (more fully represented in Figure 1) is made to afford a passage from the lower space in the cylinder beneath the piston to the channel C, through which the steam may escape into the outer air, or be directed and applied to heating fluids or other useful purposes. It will be obvious that if the cock be turned one quarter of a turn in either direction, it will make a communication (Figure 3) from the boiler passage b to the lower part of the cylinder, by or through a, at the same time that the passage r from the upper part of the cylinder will communicate with c, the passage for conveying off the same steam. P, Q, is the piston-rod moving between guides, and driving the crank R, S, by means of the rod Q,R the axis of which crank carries the fly T, and is the first mover to be applied to drive machinery, as at S and W, Figure 2.
The alternations of action are made by the successive pressure of the steam above and below the piston, and these are effected by turning the cock a quarter turn at the end of each stroke by means of the following apparatus, most fully delineated in Figure 1. x, y, is a double snail, which in its rotation presses down the small wheel 0, and raises the weight N by a motion on the joint M of the lever 0, N, from which proceeds downwards an arm, M, L, and consequently the extremity L is at the same time urged outwards. This action draws the horizontal bar I, and carries the lever or handle H, I, which moves upon the axis of the cock G through one-fourth of a circle. It must be understood that H, I, is foreshortened (the extremity I being more remote from the observer than the extremity H), and also that there is a click and ratchet-wheel in the part H, which gathers up during the time that L is passing outwards, and does not then move the cock G. But that when the part x of the snail opposite 0, that is to say, when the piston is about the top of its stroke, then the wheel 0 suddenly falls into the concavity of the snail, and the extremity L by its return at once pushes I, H, through the quarter circle, and carries with it the cock G, and turns the steam upon the top of the piston, and also affords a passage for the steam to escape from beneath the piston; every stroke, whether up or down, produces this effect by the half turn of the snail, and reverses the steam-ways as before described. Or, otherwise, the cock may be turned by various well-known methods, such as the plug with pins or clamps striking on a lever in the usual way, and the effect will be the same, whether the quarter turns be made back or forward, or by a direct circular motion, as is produced by the machinery here delineated, but the wear of the cock will be more uniform and regular if the turns be all made the same way. In the steam-engines constructed and applied according to our said Invention, the steam is usually let off or conducted out of the engine, and in this case no vacuum is formed in the engine, but the steam, after the operation, is or may be usefully applied as before mentioned. But whenever it is found convenient or necessary to condense the steam by injection water, we use a new method of condensing by an injection above the bucket of the air-pump; and by this Invention we render the condenser or space which is usually constituted or left between the said bucket and the foot-valve entirely unnecessary, and we perfectly exclude the admission of any elastic fluid from the injection water into the internal working spaces of the engine.
In Figure 2 is represented a method of heating the water for feeding the boiler, by the admission of steam after its escape through c into the cistern f. The steam passes under a false bottom e, perforated with small boles, and heats the water therein, a portion of which water is driven at every revolution of the fly by the small pump k, through l, z, into the boiler A. We also on some occasions produce a more equable rotary motion in the several parts of the revolution of any axis moved by steam-engines, by causing the piston-rods of two cylinders to work on the said axis by cranks at one quarter turn asunder. By this means the strongest part of the action of one crank is made to assist the weakest or most unfavourable part of the action in the other, and it becomes unnecessary to load the work with a fly.
Figure 4 is an upright section, and Figure 5 is a plan of the engine, with rollers for pressing or crushing sugar-canes, moved by a steam-engine improved and applied according to our said new Invention. B is a case, in the form of a drum or cylinder, suspended upon two strong trunnions or pivots at 0 and 0, its flat ends standing upright; within the iron case is fixed a boiler A, not much smaller in its dimensions, but so as to leave a vacant space between itself and the case, and within the boiler is fixed a fire-place, having its grate above the ash-hole D; the heated vapour and smoke rises at the inner extremity, and passes through two flues E, E, Figure 5, which join above at E, m, Figure 4, in the chimney E, which is there loosely applied, and is slung between centres in a ring at F. The working cylinder C, with its piston, steam-pipe, nozzle, and cock, are inserted in the boiler as here delineated. The piston-rod drives the fly T, T, upon the arbor of which is fixed a small wheel, which drives a great wheel upon the axis of the middle roller. The guides are rendered unnecessary in this application of the steam-engine, because the piston-rod is capable, by a horizontal vibratory motion of the whole engine upon its pivots 0, to adapt itself to all the required positions, and while the lower portion of the chimney E, m, Figure 4, partakes of this vibratory motion, the upper tube E, F, is enabled to follow it by its play upon the two centres or pivots in the ring F. In such cases or constructions as may render it more desirable to fix the boiler with its chimney and other apparatus, and to place the cylinder out of the boiler, the cylinder itself may be suspended for the same purpose upon trunnions or pivots in the same manner, one or both of which trunnions or pivots may be perforated so as to admit the introduction and escape of the steam, or its condensation as before mentioned. And in such eases, when it may be found necessary or expedient to allow of no vibratory motion of the boiler or cylinder, the same may be fixed, and the method of guides be made use of, as in Figure 1 or 2. The manner in which the cock is turned is not represented in these two drawings, but every competent workman will, without difficulty, understand that this effect may be produced by the same means as in Figure 1, or otherwise by the stroke of pins duly placed in the circumference of the fly, and made to act upon a cross fixed on the axis of the cock, or otherwise by the method used in the carriage, Figure 6, an hereinafter described.
The steam which escapes in this engine is made to circulate in the case round the boiler, where it prevents the external atmosphere from affecting the temperature of the included water, and affords, by its partial condensation, a supply for the boiler itself, and is or may be afterwards directed to useful purposes as aforesaid.
Figure 6 is a vertical section, and Figure 7 the plan of the application of the improved steam-engine to give motion to wheel-carriages of every description. B represents the case, having therein the boiler with its fire-place and cylinder, as have been already described in Figure 4.
The piston-rod P, Q, Figure 7, is divided or forked, so as to leave room for the motion of the extremity of the crank R. The said rod drives a cross-piece at Q backward and forward between guides, and this cross-piece, by means of the bar Q, R, gives motion to the crank with its fly F, and to two wheels T, T, upon the crank axis, which lock into two correspondent wheels U upon the naves of the large wheels of the carriage itself. The wheels T are fitted upon round sockets, and receive their motion from a striking box or bar S, X, which acts upon a pin in each wheel. S, Y, are two handles, by means of which either of the striking boxes S, X, can be thrown out of gear, and the correspondent wheel W by that means disconnected with the first mover for the purpose of turning short or admitting a backward motion of that wheel when required. But either of the wheels W, in case of turning, can be allowed considerably to overrun the other without throwing S, X, out of gear, because the pin can go very nearly round in the forward motion before it will meet with any obstruction. The wheels U are most commonly fixed upon the naves of the carriage-wheels W, by which means a revolution of the axis itself becomes unnecessary, and the outer ends of the said axis may consequently be set to any obliquity, and the other part fixed or bended, as the objects of taste or utility may demand. The fore wheels are applied to direct the carriage by means of a lever H, and there is a check-lever which can be applied to the fly, in order to moderate the velocity of progression while going down bill.
In the vertical section, r, u, denotes a springing lever, having a tendency to fly forward. Two levers of this kind are duly and similarly placed near the middle of the carriage, and each of them is alternately thrown back by a short bearing lever S, t, upon the crank axis, which sends it home into the catch u, and afterwards disengages it when the bearing lever comes to press upon V, in which case the springing lever flies back. A cross-bar or double handle o, p, is fixed upon the upright axis of the cock, from each end of which said cross-bar proceeds a rod p, q, which is attached to a stud q, that forms part of the springing lever r, u. This stud has a certain length of play, by means of a long hole or groove in the bar, so that when the springing lever r, u, is pressed up, the stud slides in the groove without giving motion to p.
When the other springing lever is disengaged, it draws the opposite end of p, o, by which means p draws the long hole at q, up to its bearing against the stud, ready for the letting off of that first-mentioned springing lever. When this last-mentioned lever comes to be disengaged, it suddenly draws p back, and turns the cock one quarter turn, and performs the like office of placing the horizontal rod of the other extremity of p, o, ready for action by its own springing lever. These alternations perform the opening and shutting of the cock, and to one of the spring levers r, u, is fixed a small force-pump w, which draws hot water from the case by the quick back-stroke, and forces it into the boiler by the stronger and more gradual pressure of S, t. It is also to be noticed, that we do occasionally, or in certain cases, make the external periphery of the wheels W uneven, by projecting heads of nails or bolts, or cross-grooves, or fittings to railroads when required and that in cases of hard pull we cause a lever, bolt, or claw, to project through the rim of one or both of the said wheels, so as to take hold of the ground but that in general the ordinary structure or figure of the external surface of these wheels will be found to answer the intended purpose. And, moreover, we do observe and declare, that the power of the engine, with regard to its convenient application to the carriage, may be varied, by changing the relative velocity of rotation of the wheels W, compared with that of the axis S, by shifting the gear or toothed wheels for others of different sizes properly adapted to each other in various ways, which will readily be adopted by any person of competent skill in machinery. The body of the carriage M may be made of any convenient size or figure, according to its intended uses.
And lastly, we do occasionally use bellows to excite the fire, and the said bellows is worked by the piston-rod or crank, and may be fixed in any situation or part of the several engines herein described, as may be found most convenient."
A little repetition may be necessary in drawing the reader's attention to the number and variety of valuable practical inventions in this notable patent specification of 1802. Figures 1, 2, 3, show a portable high-pressure steam-engine, the, boiler of which is a hollow globe of cast iron, having the under side indented for the fire-place. A casing of iron, coated with fire-clay, forms the flues surrounding the boiler. The chimney is of iron, attached to the flue. The cylinder, of most simple form, is let partly into and fixed in the boiler. From its top, two upright bars serve as supports for the crank-shaft, and also as guides for the piston-rod. A roller on the top of the piston-rod causes it to work easily in the guides. A four-way cock is moved by a compound eccentric, called a snail. If the action of the eccentric, which was nearly, or quite, a new thing, was unsatisfactory, the cock might he worked by the well-known method of tappets. A throttle-valve regulates the supply of steam. An air-pump may be used, condensing in the exhaust-steam pipe in preference to the larger condensing vessel used in the Watt engine; or the engine may be worked as a puffer without condensing; in which ease the waste steam warms the feed-water, which is forced into the boiler by a plunger-pole.
Figures 4 and 5 show his high-pressure portable steam-engine applied to a crushing machine. The boiler in that engine is a cylinder of wrought iron with flat ends, having three internal wrought-iron tubes. The fire-place is in the lower of the tubes, which tube extends the length of the boiler, and returns to the fire-door end as a double tube, where it joins the wrought-iron chimney. The boiler is enclosed in a case slightly larger, just allowing space for the passage of the used steam, thus sheltering the boiler from external cold, and supplying hot feed-water, or reserve steam for other purposes.
The boiler is supported on two centres or trunnions, on which it moves or oscillates. The cylinder is fixed in the steam space of the boiler. The piston-rod attaches direct to the crank. The trunnions serve as steam-ways. The chimney is wrought iron, suspended on a centre to allow for the oscillation of the boiler or the boiler may be fixed, the cylinder alone oscillating. Two cylinders are recommended in preference to one, with cranks at right angles.
The crank-axle is fixed on a cast-iron frame, which also supports the boiler, chimney, and crushing rollers the whole apparatus being complete, without masonry or woodwork.
How very distinct is this description of engines, patented seventy years ago: and these were not mere floating ideas, but the result of true and practical knowledge, tested by prior experience.
This particular combination of parts is similar, in a practical sense, to the double-cylinder, oscillating marine engines of the present day. The tubular boiler of small bulk, so small that it might reasonably oscillate. The boiler-flues wholly internal. The cylinder and the boiler protected from the cold, and the feed water heated by the used steam on its way to the chimney: everything small, and portable, and complete, and attached to the frame that supported the machine to be put in motion. Trial engines had been constructed before the date of the patent to prove their efficiency.
Figure 6 is of a locomotive and carriage for common roads. The boiler is cylindrical, made of wrought iron, with two internal tubes, for fire-place and flue, called the U, or return tube. The cylinder is fixed in the boiler, and placed in a horizontal position, close behind the driving axle. The end of the piston-rod is split into four rods, working in a guide, that the crank-axle may be brought near to the cylinder. Changeable tooth-wheels with couplings connect the crank-axle with the driving wheels. A fly-wheel equalizes the movement and serves as a brake. The four-way cock is worked by spring levers, resting against projections on the crank-shaft, being an eccentric simplified. A spring lever also works the feed-pole. The two driving wheels are of wood, about 10 feet in diameter. The two guide-wheels about 4 feet. Nearly the whole weight of machinery and passengers comes on the driving wheels. The gear-wheel on the crank-axle is 3 feet in diameter, working into a 4-feet on the driving axle, thus increasing the power of the cylinder. Those gear-wheels could be shifted, to vary the power or speed. The fire-door and chimney were both at the back end, but are not shown. The framing is of wrought iron. The whole engine is new in design, and totally different from the first Camborne engine. The horizontal cylinder takes the place of the earlier vertical cylinder. The forked piston-rod is the mechanical novelty that has since become widely useful, being what is now known as the side rod, or side beam and cross-head movement, largely used in steamboats.
Neither of the drawings shows the passage of the waste steam into the chimney. The steam-blast and the adhesion of the wheels were stumbling-blocks to a generation following Trevithick. He saw both of them plainly, though the best form of the blast-pipe was not quite decided on, and therefore not drawn. In the specification he says of the first drawing,- "The steam may escape into the outer air, or be directed and applied to heating fluids, or other useful purposes." And again, "but the steam, after the operation, is or may be usefully applied as before mentioned." In describing the second engine,— "The steam which escapes in this engine is made to circulate in the case round the boiler, where it prevents the external atmosphere from affecting the temperature of the included water, and affords, by its partial condensation, a supply for the boiler itself, and is or may be afterwards directed to useful purposes as afore- said." In the third or locomotive engine, having a boiler very similar to that just described, he says, "and lastly, we do occasionally use bellows to excite the fire."
The bellows is not drawn any more than the blast-pipe, though both were used in the first Camborne engine prior to the patent, but only the blast-pipe was used after the patent. Years of experience have taught locomotive engineers that the best effect of the blast-pipe depends on its particular shape and position in the chimney. This difficulty Trevithick felt, as shown by the wording of the specification, and absence of a drawing of the pipe; but the idea was distinct, and the proof is in his constant use of the blast-pipe, from the first trial.
On the grip or adhesion of the wheels, he says "We do occasionally, or in certain cases, make the external periphery of the wheels uneven, by projecting heads of nails or bolts, or cross-grooves, or fittings to railroads when required; and that in cases of hard pull we cause a lever, bolt, or claw, to project through the rim of one or both of the said wheels, so as to take hold of the ground; but that in general the ordinary structure or figure of the external surface of these wheels will be found to answer the intended purpose.
Mr. Symons recollects distinctly Captain Andrew Vivian explaining to him and others that his partner (Trevithick) must be wrong about his proposed tram-way engine. "If the wheels slipped on the rough ground, they would slip much more on the smooth iron." This was said when the patent was being taken out, in which Trevithick and Vivian state "the grip will be found sufficient." "Trevithick was one of those men who would have his own way." On this vital question of adhesion his partner was dead against him, and in his view was backed by general opinion, which remained more or less in force for fifty or more years; while, on the other hand, his early practical inventions were clogged by the hesitating and never-carried-out patent claim of Watt. "I intend in many cases to employ the expansive force of steam, to press on the piston, in the same manner as the pressure of the atmosphere is now employed in common fire-engines. In cases where cold water cannot be had in plenty, the engine may be wrought by the force of steam only."
The failing to see or to understand what Trevithick's working experiments clearly pointed out has caused millions of money to be wasted in avoiding inclines and curves on railways that could easily have been passed by the locomotive engine and its train of carriages.
The patent having been secured, Trevithick was hard at work in Cornwall, on his portable high-pressure engines, to be adapted to any purposes where power from coal was cheaper than from men or horses.
Another common road locomotive was in progress, the trials of which are spoken of in a former chapter as the Tuckingmill locomotive. Its form was not sufficiently described by the old men who recollected its running when they were boys, to enable the writer to give a drawing. It performed longer journeys than the first one, and probably those trials suggested further changes. The engine portion was sent to London, there to be supplied with larger wheels, and a suitable carriage for passengers.
A letter of May 2nd, 1803, speaks of a high-pressure engine working very satisfactorily in London, turning and boring brass cannon for the Government, working with steam of 40 to 45 lbs. on the inch.
The Tuckingmill locomotive engine had at that time just arrived in London. The cylinder was 51 inches in diameter, with a stroke of 21 feet. With 30 lbs. of steam it worked fifty strokes a minute.
The following extract from Andrew Vivian’s account-book authenticates the dates:—
At the time it was on the road in London, my partner was not with me; it ran well; however, there was some defect, and our finances being low, we were compelled to abandon. it.
They carried their engine to London about the middle of 1803.
I well recollect its going up and down our town several times: and the rise for about 300 feet is 1 in 20.
The women used to call it the devil. Not making it answer, they sold it to a company in Merthyr Tydfil, in Wales, where it ran on a tramroad.
My father went to London in 1801, and again in 1802. He himself worked the engine when it ran from Leather Lane, from the shop of Mr. Felton (who built the carriage, and he and his sons were with the engine all the first day it ran), through Liquorpond Street, into Gray's Inn Lane, by Lord's Cricket Ground, to Paddington and Islington, and back to Leather Lane.
Mr. Gurney never saw the engine that was built here, for it was destroyed by fire before he came to Camborne with me, as stated in my father's letter.
This second locomotive, tried in Camborne in the latter part of 1802 or commencement of 1803, was sent to London in January, 1803. William West was then at Harvey's foundry, in Cornwall, preparing a new cylinder and still in February and March he was there preparing a new boiler, after which he was for five months in London, about the steam-carriage; and in August, Felton was paid for building the coach.
The London locomotive of 1803 was a great improvement on the former ones: it was not so heavy and the horizontal cylinder, instead of the vertical, added very much to its steadiness of motion; while wheels of a larger diameter enabled it the more easily to pass over bits of bad road, which had brought the Camborne one to a standstill. The boiler was wholly of wrought iron, and, with the engine attached to it, was put together at or near Felton’s carriage shop in Leather Lane; Trevithick, Andrew Vivian, and William West, were with it and Arthur Woolf (then in Trevithick's pay with the first high-pressure sent to London) came to see what was going on.
Andrew Vivian ran it, one day, from Leather Lane, Gray's Inn Lane, on to Lord's Cricket Ground, to Paddington, and home again by way of Islington — a journey of half a score miles through the streets of London. Trevithick was not on the engine on that occasion. Andrew Vivian was not an engineer, and would not have ventured on so long a run bad there not been prior proof of what the engine could do; and the fact of an altered cylinder and boiler having, been under construction in Cornwall after the locomotive had been sent to London, proves that several trials had been made, and changes found necessary.
Captain Joseph Vivian recollects that about 1803, his father, then a captain of a vessel, on his return from London told them that he and his nephew, John Vivian, had been invited to take a bit of a drive with Captain Trevithick and Captain Andrew Vivian on their steam-carriage: they went along pretty well through a good many streets, and were invited again for the next day; but Captain Vivian thought he was more likely to suffer shipwreck on the steam-carriage than on board his vessel, and did not go a second time.
Captain John Vivian, H.M.P.S., was, about the middle of 1803, on board his uncle's vessel in London, and often went to see the steam-carriage putting together at a coach-builder's shop in Leather Lane. Captain Trevithick and Captain Andrew Vivian were there, and Mr. William West was the principal man in putting the engine together. Mr. Arthur Woolf frequently came in, he being engaged close by as an engineer in Meux's Brewery.
Thinks the engine had one cylinder, and three wheels; the two driving wheels behind were about 8 feet in diameter. The boiler and engine were fixed just between those wheels.
The steering wheel was smaller, and placed in front. There were some gear-wheels to connect the engine with the driving wheels. The carriage for the passengers would hold eight or ten persons, and was placed between the wheels, over the engine, on springs. One or two trips were made in Tottenham Court Road, and in Euston Square. One day they started about four o'clock in the morning, and went along Tottenham Court Road, and the New Road, or City Road: there was a canal by the side of the road at one place, for he was thinking how deep it was if they should run into it. They kept going on for four or five miles, and sometimes at the rate of eight or nine miles an hour. I was steering, and Captain Trevithick and some one else were attending to the engine. Captain Dick came alongside of me and said, ‘She is going all right.' ‘Yes,' said I, ‘I think we had better go on to Cornwall.' She was going along five or six miles an hour, and Captain Dick called out, ‘Put the helm down, John! and before I could tell what was up, Captain Dick's foot was upon the steering-wheel handle, and we were tearing down six or seven yards of railing from a garden wall. A person put his head from a window, and called out, What the devil are you doing there! What the devil is that thing!'
They got her back to the coach factory. A great cause of difficulty was the fire-bars shaking loose, and letting the fire fall through into the ash-pan.
The waste steam was turned into the chimney, and puffed but with the smoke at each stroke of the engine. When the steam was up, she went capitally well, but when the fire-bars dropped, and the fire got out of order, she did not go well.
I heard afterwards that the framing of the engine got a twist, and she was used to drive a mill for rolling hoop-iron; and also that she ran on a tramroad laid down in Regent's Park."
In 1860, Mrs. Humblestone recollected Mr. Trevithick's steam-carriage go through Oxford Street; the shops were closed, and numbers of persons were waving handkerchiefs from the houses; no horses or carriages were allowed in the street during the trial. The carriage moved along very quickly, and there was great cheering. At that time she kept a shop next door to the Pantheon, and it, like the others, was closed. Her husband was employed with Mr. Trevithick at the Blackwall dredgers or the Tunnel.
The reader must not imagine that these few records collected of events witnessed by but very few who still live, nor that the slight notice to be found of them in written history are indications of their want of importance, or of their having been mere passing experiments. They were the first and firm steps of the young locomotive, which Trevithick laboured for years to strengthen and make useful, and which would have given to our fathers some of the benefits we receive from steam locomotion had they had the good sense to comprehend Trevithick. Two years of locomotive experiments in Cornwall were followed by six or eight months of trials in the streets of London, commencing with January, 1803, when the locomotive was forwarded from Cornwall.
The day on which Captain John Vivian steered, they started at four o'clock in the morning, going through Tottenham Court Road and the City Road, sometimes at a speed of eight or nine miles an hour, and so successfully that — in joke — they talked of keeping on until they reached Cornwall, when bad steering, rather than engine defects, brought them to a standstill. It passed through Oxford Street at a good pace, amid cheers and waving of handkerchiefs. Undoubtedly other trips were run, but we have evidence sufficient to prove that the streets of London were safely passed through by the steam-horse at about the speed of the living horse.
Felton's carriage, to carry six or eight persons, placed over the engine and boiler between the large driving wheels, was supported on springs from the engine framing, which was of wrought iron. The boiler was of wrought iron, with internal return fire-tube. The fire-door and chimney were at one end. The cylinder was fixed in the boiler horizontally, and the crank was just under the carriage: coal and water were carried on the engine platform. The steam-blast in the chimney caused the small boiler to produce the necessary quantity of steam, and the increased size of the driving wheels to 8 or 10 feet in diameter have a better grip, and enabled the engine and its load to pass more easily over road inequalities.
These continued trials and their consequent cost drained to the bottom the pockets of the inventors, and put an end for a time to locomotive experiments. The steam-carriage was sold for what it would bring, and the engine portion became a hoop-iron rolling-mill engine.
All the partners, except Trevithick, were disheartened at this result of steam travelling. He and Vivian at that time held each two-fifths of the patent, and West one-fifth; none of them received a penny, and they paid their losses as best they could.
Trevithick had learnt, however, from the shocks on the rough pavements, that a smooth road of iron was the thing to enable the steam-horse to run well, and from that time gave his thoughts to the railway form of locomotion.
It has been said that Trevithick was a pupil of Murdoch's, and learned from him the knowledge of the steam-carriage. Murdoch's model was made in 1784, when Trevithick was a boy of thirteen. Murdoch's experiments, which never bore fruit, were made in the dark and in secret. His model had a cylinder 3/4inch in diameter, with a 2-inch stroke; its boiler was a square box of copper, 4 inches on the side, heated by a lamp. Its smallness did not admit even of a liliputian engine-man, and having no guide, it could not run.
The following particulars were read at the Institute of Mechanical Engineers in 1850, and from them the writer first learnt of Murdoch's attempt, though he had lived many years among engineers within ten miles of Murdoch's residence at Redruth:-
Watt's friend and assistant, William Murdoch, took up the idea of a steam-carriage, broached by his patron, and constructed a non-condensing steam-locomotive, of liliputian dimensions, in the year 1784, the date of Watt's second patent. This locomotive, placed on three wheels, is shown in Fig. 1.
The boiler is of copper the flue passes obliquely through it and is heated by a spirit-lamp. The cylinder is 3/4inch diameter, and has 2 inches stroke; it is fixed on the top of the boiler, and the piston-rod is connected to one end of a vibrating beam, to which also is attached the connecting rod for working the crank of the driving axle.
The slide-valve is double, cylindrical, and worked directly by the beam, which strikes the shoulders of the valve-spindle and the exhaust steam passes through the hollow of the spindle, going out near the top. One of the wheels only is fixed on the crank-axle, and a single wheel is placed in front, working in a swivel frame, to allow the carriage to run in a small circle. The driving wheels are 9.5 inches diameter, and the leading wheel 4.75 inches. Notwithstanding these diminutive dimensions, this little gentleman managed to outrun the inventor on one occasion. ‘One night, after returning from his duties at the mine,' in Redruth, Cornwall, where he resided for some time, in charge of the mining engines, 'he wished to put to the test the power of his engine and, as railroads were then unknown, he had recourse to the walk leading to the church, situated about a mile from the town. This was very narrow, but kept rolled like a garden-walk, and bounded on each side by high hedges. The night was dark, and he alone sallied out with his engine, lighted the fire, a lamp under the boiler, and off started the locomotive, with the inventor in full chase after it. Shortly after he heard distant despair-like shouting it was too dark to perceive objects, but be soon found that the cries for assistance proceeded from the worthy pastor, who, going into town on business, was met on this lonely road by the fiery monster, whom he subsequently declared he took for the Evil One in propria persona.
The foregoing led the writer to make inquiries among old men at Redruth who had been intimate with Murdoch. Nothing could be learned, except an indistinct recollection that they had heard that something had been tried. As a last resource, the daughter of the “worthy" but frightened pastor was sought for, and though but a child when her parents told the story gave the following with all the freshness of a modern event:—
On a dark evening her parents, returning from Redruth to the Vicarage, were somewhat startled by a fizzing sound, and saw a little thing on the road moving in a zigzag way. Murdoch was with it; her parents knew him well. They understood that Murdoch wished the experiment to be kept secret, and she does not recollect ever hearing of it afterwards, though she frequently saw Murdoch and heard of his engineering occupations. Mr. Wilson, the agent for Boulton and Watt, was a frequent visitor at her father's house.
Only one of the driving wheels was fixed on the driving axle, which fully accounts for its travelling in zigzags.
The following letter by Trevithick, in 1803, shows that he lost no time in applying his locomotive engine to tramways: -
Boulton and Watt sent a letter to a gentleman of this place, who is about to erect some of these engines, saying that they knew the effect of strong steam long since, and should have erected them, but knew the risk was too great to be left to careless enginemen. That it was an invention of Mr. Watt, and the patent was not worth anything. This letter has much encouraged the gentlemen of this neighbourhood respecting its utility. As to the risk of bursting, they say it can be made quite secure.
I believe that Messrs. Boulton and Watt are about to do me every injury in their power, for they have done their utmost to report the explosion, both in the newspapers and in private letters, very different to what it really was. They also state that driving a carriage was their invention that their agent, Murdoch, had made one in Cornwall, and had shown it to Captain Andrew Vivian, from which I have been enabled to do what I have done. I would thank you for any information that you might have collected from Boulton and Watt, or from any of their agents, respecting their ever working with strong steam, and if Mr. Watt has ever stated in any of his publications the effects of it; because if he condemns it in any of his writings, it will clearly show that he did not know the use of it.
There will be a railroad-engine at work here in a fortnight; it will go on rails not exceeding an elevation of one-fiftieth part of a perpendicular, and of considerable length. I have desired Captain A. Vivian to wait on you to give you every information respecting Murdoch's carriage — whether the large one at Mr. Budge's foundry was to be a condensing engine or not.
The simplicity of Trevithick's question brings out the truth: "If Watt condemns the use of high steam in any of his writings, it will clearly show that he did not know the use of it."
Dr. Robison, the scientific and intimate friend of Watt, says: "It is well known that Mr. Watt retained up to the period of his death, the most rooted prejudices against the use of high steam." He also speaks of a design for a locomotive by Watt, in 1784, with a wooden boiler, and sun-and-planet wheels. Those schemes of Watt and of Murdoch may have some relation to the story that Captain Andrew Vivian was to speak of to Davies Gilbert, "whether the large one at Mr. Budge's foundry was to be a condensing engine or not."
Budge was a clever Cornish mechanic, and had small workshops and a foundry at Tuckingmill; working frequently for Trevithick, sen., prior to Watt's appearance in Cornwall. If Watt never worked with high steam, his contemplated locomotive must have been a condensing engine.
This opens up a curious question in the history of the steam-engine. It is evident that Murdoch attempted a working model of a locomotive in 1784, but failed, and Watt blamed his agent for so throwing away his time. It is also evident that Watt had his plans for a locomotive as described by Dr. Robison, and it now seems more than probable that to put his ideas into form he employed Mr. Budge, whom we have met with as the mechanic employed by Trevithick, sen., in erecting his Carloose engine of 1775, and in which an increased pressure of steam was probably used, from the improved boiler.
We may never know what passed between Budge, Watt, and Murdoch. Murdoch's model, with one driving wheel, wobbled like a lame duck, and disappeared after one brief airing on a dark night his boiler retained the weak flat sides of the low-pressure system, and Watt talked of a still weaker boiler to be made of wood. Fifty years ago the writer wondered what was carried on inside the dirty walls and windows of what had been Budge's foundry, but never dreamed that perhaps the construction had been attempted of a low-pressure steam locomotive vacuum engine, with wooden boiler and sun-and-planet wheels. There was no similarity between those proposed locomotives and Trevithick's realities.