Engineers and Mechanics Encyclopedia 1839: Railways: Trevithick and Vivian
In a bold deviation from the beaten track, it was the good fortune of Richard Trevithick and Andrew Vivian, two engineers residing at Camborne, in Cornwall, to find the path which conducted them to their object; rejecting the absurd prejudices which bad made high-pressure steam to be excluded from practice, they saw in the formidable qualities which had excited the fear of Watt and others, those very properties which fitted it to become the actuating principle of their mechanism.
Above all other considerations which swayed them in their preference of steam of a high temperature, was the power it gave of dispensing with the use of the condenser altogether; a part which, from its cumbrousness, and the difficulty of supplying it with water, rendered it far inferior even to Newcomen's imperfect apparatus for locomotive purposes.
The specification of the patent granted to Messrs. Trevithick and Vivian is descriptive of a high-pressure engine, the most simple and effective ever known, which has thus been characterized by the eloquent Mickleham:
"It exhibits in construction the most beautiful simplicity of parts, the most sagacious selection of appropriate forms, their most convenient and effective arrangement and connexion; uniting strength with elegance, the necessary solidity with the greatest portability; possessing unlimited power with a wonderful pliancy to accommodate it to a varying resistance; it may indeed be called “The Steam Engine”.
Our present business is with the application of this engine, which the specification proceeds to show in connexion with a sugar-cane mill; and, lastly, it describes its employment in propelling "wheel carriages of every description," - a purpose for which it is most admirably designed, as it contains generally those arrangements or combinations of mechanism which many of our present locomotionists call their own, and which are adhered to as essential to their machines.
We shall now quote from the specification:
"Fig 1 is a vertical section, and Fig. 2 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 fireplace and cylinder (described by the patentees in the previous part of their specification). The piston-rod P-Q, Fig. 2, is divided or forked no as to leave room for the motion of the extremity of the crank; 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 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 fixed 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 requited; 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 bonded, 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 chink lever which can be applied to the fly, in order to moderate the velocity of progression when going down hill.
“In the vertical section is shown 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 are alternately thrown back by a short bearing lever upon the crank axis, which sends it home into a catch at the end, and afterwards releases it when the bearing lever comes to press upon V, in which case the springing lever flies back. A cross bar, or double handle is fixed upon the upright axis of tire 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 seeing lever.
“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 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 the handle, and causes p to draw 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 the handle ready for action by its own springing-lever. These alterations perform the opening and shutting of the cock, and to one of the springing levers 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 a lever on the crank axis. It is also to be noticed that 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 gears 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 are 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.”
Such admirable combinations of inventive skill were never before contained in the specification of a patent; yet they are described with that unassuming brevity which belongs to matters of common occurrence. What an extraordinary contrast does the modesty of these truly clever men present, when compared with the boastings of several of our recent locomotionists, who have derived almost every thing that is of a useful character in their carriages from the foregoing specification, and from the subsequent practical application of the inventions by the patentees themselves.
There are thousands of persons now living in London who saw the steam-coaches of Messrs. Trevithick and Vivian running about the waste ground in the vicinity of the present Bethlehem Hospital; and likewise in the neighbourhood or site of Euston Square. This was thirty-four years ago; nevertheless, Dr. Lardner says, at page 246 of Iris Treatise on the Steam-engine,
"First and most prominent in the history of the application of steam to the propelling of carriages on turnpike roads, stands the name of Mr. Goldsworthy Gurney. Numerous other projectors, as might have been expected, have followed in his wake. Whether they, or any of them, by better fortune, greater public support, or more powerful genius, may outstrip him in the career on which he has ventured, it would not perhaps at present be easy to predict. But whatever may be the event, to Mr. Gurney is due, and will be paid, the honour of first proving the practicability of the project; and in the history of the adaptation of the locomotive engine to common roads, his name will stand before all others in point of time; and the success of his attempts will be recorded as the origin and cause of the success of others in the same race."
We know not to what cause to attribute such an obvious misstatement of facts; for it is impossible for any one who attends to the chronology or history of the subject, not to see at once that there are about as many untruths in this panegyric as there are lines.
It is extremely painful to us to make these observations upon a gentleman of such high scientific attainments as the learned Doctor but his just influence upon the public mind, renders it imperative upon us to notice this common error which he has fallen into, in order that the fairly earned honours of those truly eminent mechanics, Trevithick and Vivian, be not thus sacrilegiously trampled in the dust!
Mr. Gurney's first patent for a steam-carriage was in the year 1825, and will be found described in its proper chronological position. We will, however, in this place, merely observe, that the mechanic who peruses the said specification will instantly recognise the chief arrangements of Trevithick and Vivian, and if he reads on to the end of the specification, he will find that the sole claims to invention in this steam-carriage are in the words following:
"I claim the use of a roller or rollers, wheel or wheels, to the upper ends of my said propellers, reacting against a straight and smooth rail or plane affixed under, and being a part of the carriage, such rail or plane being parallel, or nearly so, to the soles or bottom of the carriage wheels, whereby the carriage itself is enabled to be rolled over the upper ends of the said propellers, crutches, or feet, by the mechanical power employed."
It is worthy of observation, that however a patentee may be disposed to vaunt and puff before the "enlightened public," there is too much risk attending the making of unfounded pretensions in the specification of a patent, wherein the claims to invention must be exactly defined; for if any thing be claimed that is not new, the whole patent is thereby rendered void.
In the claims, therefore, of a specification, we look for the naked truth; and in this case we find it to be not a steam-carriage, but a useless roller put under the body of the vehicle! These appendages, however, of guide rollers, it may be remarked, were first applied to preserve the rectilineal motion of the piston-rod in the beautiful high-pressure engines of Trevithick and Vivian, and they have been applied in a thousand similar ways ever since. Mr. Gurney thinks, however, that nobody put rollers to their crutches before him, and that, consequently, he invented steam-carriages.
And can it be for proposing to use these crutches, which it is notorious were long before patented and used, and found wanting, (by Brunton, in 1813, Baynes, in 1820, Gordon, in 1824, &c.) that Dr. Lardner scatters to the winds all the skill and talent, not only of the gentlemen we have named, but of all others who preceded Mr. Gurney in the building of steam-carriages! The inquiry naturally follows, what became of the celebrated crutches of “the powerful genius?" To answer it, we have referred to Alexander Gordon's interesting 'Treatise on Elemental Locomotion#, and we there find it stated at page 55, that they were "entirely abandoned, the wheel being found not only to be sufficient for impelling the carriage, but also to allow considerable free traction."
Now it is of importance to notice, that although Trevithick and Vivian stated in the plainest language in their specification, twenty-four years prior, that the ordinary wheels alone were sufficient to propel; Dr. Lardner and other writers, nevertheless, lead their readers to suppose that Trevithick and Vivian were the authors of this error. At page 247 of his Treatise, the Doctor observes, -
“The mistake which so long prevailed in the application of locomotion on railroads, and which, as we have shown, materially retarded the progress of that invention, was shared by Mr. Gurney. Without reducing the question to the test of experiment, he took for granted, in his first attempts, that the adhesion of the wheels to the road was too slight to propel the carriage. He was assured, he says, by eminent engineers, that this was a point settled by actual experiment. It is strange, however, that a person of his quickness and sagacity did not inquire after the particulars of these actual experiments. So, however, it was; and taking for granted the inability of the wheels to propel, he wasted much labour and skill in the contrivance of levers and propellers, which acted on the ground in a manner somewhat resembling the feet of horses, to drive the carriage forward. After various fruitless attempts of this kind, the experience acquired in the trials to which they gave rise, at last forced the truth upon his notice, and he found that the adhesion of the wheels was not only sufficient to propel the carriage heavily laden on level roads, but was capable of causing it to ascend all the hills which occur on ordinary turnpike roads."
This unqualified admission, by Dr. Lardner, of the entire uselessness of the only invention claimed by Mr. Gurney in his patent steam-carriage of 1825, also shows that the Doctor conceived that Mr. Gurney was the individual who "found out" this error of "eminent engineers;" whereas the fact is incontrovertible that hundreds of thousands of miles had been previously travelled with plain wheels upon railways, where the adhesion of the former to the surface is not one-tenth of that upon the common road.
It also shows that the learned author was entirely unacquainted with the many plans for locomotion, by numerous ingenious men (hereafter noticed) who never entertained the idea that the adhesion of the wheels upon the surface was insufficient to propel. And than it appears that he, whose brilliant talents we are told had dispelled an age of darkness, was the only individual who could not see the perfect inutility of confessedly his own contrivance in the specification to which we have alluded and for which he has been called the inventor of steam-carriages!
We must, however, terminate this digression from the path we set out upon, by making another extract from Dr. Lardner's Treatise; the first portion of which (page 179) we are pleased to add, because the admirable clearness with which the knowledge it conveys is given, is, in some degree, compensatory for the latter part, to which our complaint alluded.
"It is a singular fact, that in the history of this invention considerable time and great ingenuity were vainly expended in attempting to overcome a difficulty which, in the end, turned out to be purely imaginary. To comprehend distinctly the manner in which a when carriage is propelled by steam, suppose that a pin or handle is attached to the spoke of the wheel at some distance from its centre, and that a force is applied to this pin in such a manner as to make the wheel revolve; if the face of the wheel and the surface of the road were absolutely smooth and free from friction, so that the face of the wheel would slide without resistance upon the road, then the effect of the force thus applied would be, merely to cause the wheel to turn round; the carriage, being stationary, the surface of the wheel would slip or slide upon the road as the wheel is made to revolve.
"But if, on the other hand, the pressure of the face of the wheel upon the road is such as to produce between them such a degree of adhesion as will resider it impossible for the wheel to slide or slip upon the road by the force which is applied to it, the consequence will be, that the wheel will only turn round in obedience to the force which is applied to it; the consequence will be, that the wheel will roll upon the road, and the carriage will be moved forward through a distance equal to the circumference of the wheel each time it performs a complete revolution. It is obvious that both of these effects may be partially produced; the adhesion of the wheel to the road may be insufficient to prevent slipping altogether, and yet it may be sufficient to prevent the wheel from slipping as fast as it revolves. Under such circumstances the carriage would advance, and the wheel would slip. The progressive motion of the carriage during one complete revolution of the wheel would be equal to the difference between the complete circumference of the wheel and the portion through which, in one revolution, it has slipped.
"When the construction of travelling steam-engines first engaged the attention of engineers, and for a considerable period afterwards, a notion was impressed upon their minds that the adhesion between the face of the wheel and the surface of the road must necessarily be of very small amount, and that in every practical case the wheels thus driven would either slip altogether, and produce no advance of the carriage, or that a considerable portion of the impelling power would be lost by the partial slipping or sliding of the wheels. It is singular that it should never have occurred to the many ingenious persons who, for several years, were engaged in such experiments and speculations, to ascertain, by experiment, the actual amount of adhesion in any particular case between the wheels and the road. Had they done so, we should probably now have found locomotive engines in a more advanced state than that to which they have attained. To remedy this imaginary difficulty, Messrs. Trevithick and Vivian proposed to make the external rims of the wheels rough and uneven, by surrounding them with projecting heads of nails or bolts, or by cutting transverse grooves on them. They proposed, in cases where considerable elevations were to be ascended, to cause claws or nails to project from the surface during the ascent, so unto take hold of the road."
Now, if the specification of these injured men be referred to, it will be observed that the imagination of our author has helped him in his statement; that it is only in peculiar cases that they proposed to put into action their beautiful contrivance of. the clawing, or ribbed wheels and mils, the use of which in ascending inclined planes is unquestionable, especially as the latter were constructed then of much greater declivities than they are usually now: and to prevent any mistake in the matter, they distinctly declare, "that in general the ordinary structure or figure of the external surface of these wheels will be found to answer the intended purpose!"
All comments on such facts are unnecessary; we therefore proceed to give the reader another and very early modification of Messrs. Trevithick and Vivian's patent locomotive carriage, as it was applied upon a very indifferent tramroad; in which carriage, as in the former, the propulsion was effected solely by the adhesion of plain wheels upon the trams; nevertheless, on its first trial, it drew ten tons of bar iron after it, besides the carriages, for nine miles, at the rate of five miles an hour, without stopping once, and, therefore, carried beside, a heavy load of water and fuel.
The minor arrangements of this carriage have been variously described by different authorities, owing probably to the circumstance that several carriages were built at the time possessing these variations; but the following vertical section conveys all that seems to be essentially required.
The boiler a-a is cylindrical, with a fire-door b at one end of the cylinder; at c is the fireplace, from which is the principal flue, the parts being shown by dots, as they are supposed to be situated on one side of the vertical plane, through which our section is made; which will be perfectly understood by reference to the plan of the fireplace and flues given in our account of the Sans Pareil engine by Hackworth. The flue, therefore, is turned at e, then recurred, and continued to the chimney y. By this excellent arrangement (invented by the patentee, and which has ever since been distinguished by the name of the Trevithick boiler) a great economy of fuel was effected, as the greater portion of the heat must inevitably be taken up by the water. The lower part of the working cylinder h is immersed in the boiler, and the upper has a jack, around which the fresh hot steam circulates freely, so that no loss of power can be sustained by the cooling influence of the air upon the cylinder, as was previously the case.
Above the cylinder is the four-way cock i, for admitting and discharging the steam alternately; in the latter operation the waste steam was discharged along a pipe j into the chimney, which contrivance alone, if now patentable, would make the inventor rich; since its great efficacy in increasing the draught of air through the fire, causes an increased production of steam, while it gets rid of the nuisance of the waste steam, in a manner so desirable as to render it now of indispensable necessity. The upper end of the piston rod is furnished with a cross bar, which is placed in a direction at right angles to the length of the boiler, and also to the piston rod. This bar is guided in its motion by sliding in two perpendicular rods fixed to the sides of the boiler, and parallel to each other. To the ends of this cross bar are joined two connecting rods, the lower ends of which work two cranks, fixed to the extremities of the axis which carries the running wheels, the axis extending across and beneath the boiler, and immediately under the centre of the steam cylinder this arrangement is best seen in Fig. 1 of the following diagrams, extracted from Mr. Alexander Gordon's Treatise on Elemental Locomotion; Fig. 1 exhibiting an end elevation of the carriage, and Fig. 2 a side elevation of the same. Mr. Gordon has, however, omitted the chimneys, probably for want of space; and the eduction pipe is shown as turned up vertically to puff the steam into the air instead of into the chimney; which Mr. Gordon afterwards states was an invention of Mr. Trevithick's, but that the latter had "no intention or expectation of improving the draught in the chimney thereby."
From the high respect we entertain towards the author, we regret that such an unfair remark should have escaped him: it is, therefore, with some satisfaction that we observe, on the next page of his book, the following acknowledgment in favour of the true inventor of steam-carriages:-
"It will not be a matter of surprise, that at a period token turnpike roads were very ill made, after experimenting on the present site of Euston Square, and a few other places, the inventor discontinued his attempts on common roads, and confined his operations to a railway."
Those "very ill-made roads" have now become converted into what the clever Colonel Maceroni aptly denominates "billiard-table roads;" and it is a matter of fact, that Gurney's carriages, made in every essential respect after Trevithick's models, did, occasionally, run upon them; and so did the carriages of many other locomotionists; some prior, some subsequent to Gurney; some decidedly superior to his, and all those that were inferior, were incapacitated from proceeding beyond preparatory trials, by the want of that material with which gentlemen of fortune, then unacquainted with steam locomotion, had so lavishly furnished Mr. Gurney.
Notwithstanding all these indisputable facts, we find Mr. Gordon coinciding with Dr. Lardner, in ascribing every thing to the inventive genius of Mr. Gurney; in defiance, too, of their own admission, that the carriage, which they necessarily infer could not run (although it did, on the site of Easton Square), when transferred to a common Welch tramroad of 1804, drew after it as many waggons in addition as contained ten tons of bar iron, besides a heavy load of water and fuel, making in all probably about 20 tons.
This fact being admitted by the authors just quoted, it becomes of importance to show their consistency, in stripping the laurels from the head of Trevithick, to deck that of Gurney. By reference to Mr. M‘Neill's table of resistances, given by Mr. Gordon at page 337 of his work, it will be seen that upon the best broken stone road (such as Gurney's carriages ran upon) it requires a tractive power of 43 lbs. to move one ton upon a level. To ascertain what force is required to move the same load upon a common tram-road, we refer to Mr. Palmer's experiments on the Llanelly and Surrey tram-roads, the former of which he found by hiss dynamometer to be one-fifty-ninth of the weight, and the latter one-sixtieth of the weight. Now one-sixtieth of a ton is 375 lbs.; the force required to move a ton upon the last mentioned is therefore only about two-fifteenths less than on Mr. M‘Neill's best roads. According to these data (the only data which we can find) it is incumbent on Messrs. Gordon, Lardner, and M'Neill, (the latter gentleman being guilty of the same idolatry as the former) to show that Mr. Gurney's carriage was competent to draw after it, upon Mr. M‘Neill's road, the same load as that drawn by Trevithick's upon the tramway, minus the aforesaid difference of two-fifteenths.
These gentlemen will of course not attempt any thing of the kind, for they must know well, that which thousands of our readers bare often witnessed, that Gurney's carriage generally had its full work to do, without any tail at all. These gentlemen will surely not dispute their own data, nor say that Messrs. M`Neill and Palmer made their dynamometers incline to their own views. Let them, however, estimate the errors how they please; they cannot, by any established data founded upon authenticated disinterested experiments, show, that a light steam carriage, which performed the work they admit Trevithick's did upon the tram, would not be able to run upon our present roads better than Gurney's did; or, at the least, quite as well. We may, therefore, confidently expect, that a due sense of justice will induce these eminent authors, in the next editions of their valuable works, to insert, instead of the name of Gurney, that "Trevithick’s name stands before all others in point of time, and his admirable high pressure engines and locomotive carriages will be recorded as the origin and came of the success of others in the same pursuits.”
We described at page 381, the edge-rail of the Penryhn slate quarries; but it appears from a letter inserted in the Repertory of Arts, that the inventor, Benjamin Wyatt, subsequently proposed to make some alterations therein. It was found that the oval-formed rail had a tendency to wear the concave rims of the wheels away very fast into hollows, which fitted so tight upon the rail as to create great friction, and render it necessary to change the wheels very often. It was accordingly proposed to substitute for them a rail and wheel formed in the manner represented in the annexed drawing.
Fig.1 is a section of the rail, rim of wheel, and sill. Fig. 2, a plan of one end of sill. Fig. 3, section, on a smaller scale, of both rails and sills, which are only two feet apart. The rail a is 4 feet 6 inches long; b is a flange 2 inches long, cast to each end of the rail, to slide into the dovetail of the sill e; e is the sill, now of cast-iron; the wheels c are also of cast-iron, only 14 inches in diameter, and weigh 38 lbs. each.