the opposite ends of the box, are compressed, and gradually bring the carriages to a state of rest. By having the diameter of the rod, B B, a little larger, from н to в, and K to B, and likewise within the rest at D, forming a shoulder at those places; and by having a moveable collar, acting against the shoulder, and embracing the end of the springs, then both compartments of the springs are brought into action at the same time. Thus, when the buffer, F, is drawn outwards, the collar at D, acting against the shoulder of the rod, compresses the spring against H, and the same with the collar, K, which presses the spring against the rest, D; then, if the buffer be forced inwards, the loose collars at H, and on the right hand side of the rest at D, acting against the shoulder of the rod, compress the springs against the rest, D, and the end of the box at к, while the rod moves through the loose collars on the left side of the rest at D, and at K. Fig. 10 shews, on a large scale, the buffer head, with the ring, to which the dragging chain is attached.

Both these last-described buffers, act in the middle of the carriage in dragging, and also when the carriages strike against each other, and are liable to the objection of the carriages rising and falling with the inequality of load; and although the object of Mr. Bergin's patent, was to obviate the oscillatory motion of the carriage, yet the action of both dragging and pushing the carriages, in the middle of the sheth, has been objected to by some engineers, as producing the effect, which it was the object of the patent to obviate.

It will be seen by Fig. 6, Plate VI., that the carriages are dragged by the middle of the sheths, and the buffers are applied at each side, and that the ends of the buffers do not meet against each other, but that a

certain space is allowed by the drag-chain. It has been found in practice, that unless the ends of the buffers are perfectly square with the body of the carriage, or with the line in which the carriage is moving, and especially in going round curves; that the buffers on one side, striking against each other, throw the carriage into an oblique direction, and produce a continued oscillatory motion. Mr. Henry Booth, of Liverpool, produced a new plan of applying the buffers, for which he obtained a patent in January 1836.

The wood engraving, opposite page 218, shews this plan, which consists of keeping the buffer heads constantly in contact with each other, by the springs acting upon them with a certain degree of pressure. This is accomplished by shortening the drag-chain, and fixing upon them draw-screws, to produce the necessary pressure against the buffer heads. Upon the dragchains, bf, are placed screws, working within two long links, or shackles, the sockets of which are spirally threaded to receive the screw-bolts. These screws are worked by a short lever, l, upon which a ball is placed, to prevent the lever from turning round; but, in practice, this is not found necessary.

Fig. 2, is a view of the chain, and screw shackles, on a scale double that of Fig. 1, or one inch to a foot, and Fig. 3, is a cross section of the lever.

The drag-chains being placed upon the hooks of the bars of the carriages, the screw is turned until the buffer heads are brought together; when the screw is turned round two or three times more, until their ends, pressing against the springs of the carriage, produce a pressure against each other, equal to about a fourth or fifth of the elasticity of the springs. This plan is adopted on the Liverpool and Manchester, the Grand Junction,

and the London and Birmingham railways, and appears to answer all the expectations of the patentee; who states, that "it gives to a train of carriages a com"bined steadiness and smoothness of motion, at rapid "speeds, which they have not, when the buffers of "each carriage are separate from those of the adjoining carriage."

CHAPTER VI.

DESCRIPTION OF THE DIFFERENT KINDS OF MOTIVE POWER USED ON RAILROADS, AND THE DISPOSITION OF THE ROAD FOR THEIR APPLICATION.

§ 1.-Different Kinds of Motive Power used at various Periods on Railroads.

In the early periods of the history of railroads, horses were exclusively used; the disposition of the general line of the road, into proper or uniform degrees of inclination, seems then to have been an object of little moment. Most of the railroads, descending in the direction the goods were to be conveyed, afforded an easy draught to the loaded carriages, and the descent was never so great, but that the empty carriages could be drawn up the acclivities. In some of the deep ravines, mounds of earth were thrown up, and some sudden and abrupt acclivities partially levelled; but trifling undulations do not appear to have been noticed. The horses, therefore, would, along the same line of road, be frequently subjected to very fluctuating degrees of draught. Upon some of the old waggonways, the horse was sometimes very heavily strained, and his action was, at other times, not at all required. When the waggons reached some of the more rapid declivities, it was the custom to unhook the horse from the fore part of the waggon, and cause him to follow behind, the waggons running of themselves. The horse thus followed, until he arrived at a part of the road, where the waggon would no longer run down; he was then again fastened

to the waggon, until he arrived at another declivity, where his action was not required; and it was no uncommon thing, to find him thus changed several times in the course of his journey. The only motive power, for a long time after the introduction of railways, was horses, and so long as the wooden rail continued in use, the general load was from two to three tons, including the weight of the carriages. The only guide, in the formation of the road, appears, then, to have been to enable the horse to drag that weight, and the road was sloped accordingly. It is interesting, to trace the gradual advancement towards the present state of improvement, from the old roads, to those successively formed, at the different steps of their progress; and the quantity of goods conveyed, at different periods, exemplify it, in a very distinct manner. While the wooden rails without plates continued, the road followed, almost always, the undulations of the surface, except to avoid steep ascents; and where there was a separate road for the empty carriages, the latter invariably did so. Νο attempts seem to have been made, to avail themselves of the action of gravity down the steep planes; and the most disastrous effects were occasionally produced, by the waggons running "amain," down the steep declivities. A brake, or convoy, being used, to regulate their descent, this brake was pressed by the man with more or less force, according to the declivity of the road, or the velocity with which he wished the waggons to descend. In wet or damp weather, the wheels, by licking up the dirt and mud from the rail, became so slippery, that the action of the brake was almost destroyed; and the attendant having thus no power over the loaded carriage, it frequently got away, destroying every thing in its course, perhaps killing the horses that happened to be upon the declivity, and was, finally,