" 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 or the wheel and the sur face 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 sin gular that it should never have occurred to the many ingenious persons who, for several years, were engaged in such experiments and speculations, to ascer tain, 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. 7'rerithick 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 trans verse 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 as to take hold of the road." Now, if the specification of these injured men be referred to (see page 389), it will be observed that the imagina tion 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 rails, 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 • very indifferent trammed; in which carriage, as in the former, the propulsion was effected solely by the adhesion of plain wheels upon the trains; never theless, 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 arrange ments 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 he essentially required. The boiler a a is cylindrical, with a fire-door at b at one end of the cylinder ; at c is the fireplace, from which is the principal flue, the parts being shown by dote, as they are supposed to be situated on one side of the vertical plane, through which our section is made ; which will be per fectly understood by reference to the plan of the fireplace and flues given in our account of the Sans Patel: engine by Hackworth. The flue, therefore, is turned at e, then recurved, and continued to the chimney .q. By this excellent arrangement (invented by the patentee, and which 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 tipper has a jacket. 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 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 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, how ever, 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. Tre vithick'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' or the true inventor of steam carriages:— "It will not be a matter of surprise, that at a period when 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 " nave now become converted into what the clever Colonel Maceroni aptly deno minates "billiard-table roads ;" and it is,a matter of fact, that Gurney's carriages, made in every euential 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 Euston Square), when transferred to a com mon 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 lbe. 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 his dynamo meter to be ene-fifty-ninth of the weight, and the latter one-sixtieth of the weight. Now one-sixtieth of a ton is 37.1 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 have often witnessed, that Gurney's carriage gene rally had its full work to do, without any tail at all. These gentlemen will surely not dispute their own data, nor say that Messrs. KNeill 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 ipon 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 " Tatviruices 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 cause 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, Mr. Benjamin Wyatt, subsequently pro posed 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 re presented 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. Kg. 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 thrail, to slide into the dovetail of the sill e ; e is the now of cast-iron; the wheels c are also of cast-iron, only 14 inches in diameter, and weigh 38 lbs. each.
In the year 1811, a patent was taken out by Mr. John Blenkinsop, coal viewer, of Middleton, in Yorkshire, foLlkertain mechanical means by which the conveyance of coals, minerals, and other articles is facilitated, and the expense attending the same rendered less than heretofore." The specification of this patent informs us that it consists of the application of a rack or toothed rail, laid down on one side of the roadway from end to end. Into this rack a toothed wheel is worked by the steam-engine ; the revolution of which wheel produces the necessary motion, without being liable to slip in descending a steep inclined plane.
The accompanying figure will convey to our readers an idea of Mr. Blenkin sop's plan. The boiler x is placed on a wooden or cast-iron frame y. Through its interior passes a wrought-iron tube, of sufficient diameter to hold the fire and grate ; this tube is carried out at the farther end of the boiler, when it is bent upwards, and continued sufficiently high to form the chimney a. a a are two working cylinders fixed in the boiler, and which work in the usual way ; the piston rods are connected by cross heads to the connecting rods b b. These connecting rods are brought down on each side of the boiler, and there joined to the cranks a c, (there being corresponding cranks on the other side of the machine,) which are placed at right angles so each other; consequently the two cranks on the first shaft are horizontal, and at their greatest power at the time the other two are passing the centre. Upon these shafts are fixed (under the boiler) two small toothed wheels, which give motion to a larger toothed wheel fixed upon an intermediate axis. A toothed wheel/ is firmly keyed to the end of the same and revolves with the intermediate wheeL The teeth off correspond with, and work into a rack R R, stretched along one side of the railway. Motion, therefore, is given by the pistons to the wheels d d, which they commu nicate to the cog-wheelf; a progressive movement being given to the carriage by the teeth taking hold of the rack.
The only objection made to this machine by Mr. E. Galloway is " that the power is applied on one side only, which must have a tendency to force the Ranges or projecting rims of the supporting wheels against the edges of the rails, by which an extra friction would be produced. This, however, is a trifling inconvenience, and is not found in practice to deduct much from the effect of the engines, several of which have, since the date of the patent, been in con stant use in drawinv coal waggons between Middleton colliery and Leeds." The ingenious Mr. Galloway observes that by this machine a load may be drawn up a much greater declivity, than by the locomotive of Messrs. Trevi thick and Vivian. But this observation, which appears to be repeated by every author on locomotion in succession, only serves to show, that they never read the specification of those able engineers ; otherwise, it would be readily per ceived that the"cross-grooved" peripheries of the wheels, and the suitable "fittings to railroads," had reference to this very invention of Blenkinsop's. It however seems that those eminent men were not only deprived of the just reward of their labour and talents, but that they were on all hands subjected to the mortification of seeing their beautiful inventions ascribed to after-comers, by whom, or their Mends,• those very inventions were actually employed to dis parage the real inventors Mr. Partington, in his history of the steam-engine, says, that Mr. Bleukinsop, in reply to queries put to him by Sir John Sinclair, stated that his patent loco motive engine, with two eight-inch cylinders, weighs five tons ; consumes two thirds of a hundredweight of coals, and fifty gallons of water per hour • draws twenty-seven waggons, weighing ninety-four tons, on a dead level, at three and a half miles per hour; or fifteen tons up an ascent of two inches in the yard ; when "lightly loaded " it travels ten miles an hour, does the work of sixteen horses in twelve hours, and costs 4001.