this shaft is another lever, communicating with the two arms, ff, Fig. 3. When, therefore, the handle, a', is turned, the combination of wheels moves the rod, c c", back and forwards, by means of the toothed rack; and if it is drawn in the direction of the dart, the lever on the shaft, e'e', presses the two arms, f'f', downwards, and, consequently, presses the brakes, u u, against the wheels; and the handle being turned so as to work the rod in the opposite direction, the brakes are drawn upwards, and, therefore, drawn from against the wheels. The combination of wheels is for the purpose of increasing the power of the handle, a', which could not otherwise be made of sufficient power, without being inconveniently long.

In Fig. 6, Plate VI., another plan of working the brake is shewn. In this plan there is a separate brake to each wheel, and not a double one, as in Fig. 3, Plate VIII. 1 Fig. 6, Plate VI., is the handle, and pinion, working into the large wheel, 2, on the axle of which is a small pinion, working the two-toothed racks, 3 and 4. Two axles, 5 and 6, are fixed to the frame of the carriage; on each of these axles an arm is firmly fixed, projecting downwards, and upon these arms the brakes, which act against the travelling wheels of the carriage, are fastened. Upon the same axles, at 5 and 6, other two levers, or arms, are fixed, both of them projecting upwards. When, therefore, the handle is turned towards the left, the rod 3, and arm 5, are pushed forwards, and, consequently, that brake is pressed against the wheel; while, at the same time, the rod 4, and arm 6, are pulled in the opposite direction, and that brake is pressed against the other wheel; and when the handle is turned in the other direction, the brakes are taken from against the wheels. There are several other modes practised, of applying brakes to the wheels

of the carriages, which it is unnecessary here to describe.

§ 11.-Mode of coupling Carriages, or Buffing

Apparatus.

In railway travelling, the engines are necessarily very powerful, and, consequently, several carriages are dragged at a time; and these were generally fastened to each other, either by a chain, or by a bar of iron. If by the former, the inertia of one waggon, by any change of motion, is independent of the other; and, therefore, when the engine puts the first carriage in motion, it is done by a jerk, or sudden pull, and so on throughout the whole train, as each carriage is successively put in motion; and, consequently, a succession of jerks is felt by the passengers, as each carriage is put in motion. Again, when the train is stopped, or the speed slackened, the inertia of each carriage causes it to strike against the preceding one, and a succession of blows, or shocks, is felt, as each carriage successively strikes against that which precedes it; and thus the passengers are continually subjected to a succession of jerks, or shocks, whenever any change of motion takes place. When the carrriages are fastened together, by an inflexible bar of iron, the succession of jerks, or shocks, is obviated, the carriages being prevented striking against each other, and only one jerk, or blow, is felt, when the entire train is either stopped, or put in motion; but, in this case, unless the engine be more than sufficiently powerful, to drag the train forward, when in motion, at a certain velocity, it will be incapable of putting the whole mass of carriages, from a state of rest, into motion, without very considerable delay. If the carriages are not fastened together by an in

flexible bar, but by a chain, this allows each carriage to move a short distance, before the next is put in motion; then each carriage is put into motion in succession, and the inertia is subdivided into as many efforts as there are carriages.

Whether, however, the changes of motion of the train of carriages, is effected as one mass, or in separate carriages; every change produces either a jerk, or a shock, or both, and these are greater, the more rapid the rate of travelling, and it required some contrivance to obviate this inconvenience. The most obvious was a spring, by which the blow, or jerk, was not instantaneously transmitted to the other carriages, but gradually, and through the elasticity of the springs. Upon the Liverpool and Manchester railway, which was the first where rapid travelling was begun, and where the necessity first existed, the carriages were fitted up with springs in the following manner.

Fig. 6, Plate VI., shews the plan used on that railway; an elliptic spring, d d, is placed horizontally in the middle of the frame of the carriage, the back of which rests against the stop at c, and the two ends rest against the stops at d d. The dragging chain, b, is fastened to the middle of the spring, by the rod, bb; and the dragging chain, f, is fastened to the ends, dd, of the spring, by the two diagonal rods, e' e'.

Buffer heads, or cushions, stuffed with hair, or some other elastic substance, gg, hh, are placed at the ends of the outer side frames of the carriage. The rods, upon which the buffer heads, g g, are fixed, passing through the ends of the side frame of the carriage, and these side frames being constructed of two pieces, kept apart by studs, the rods pass within the frame, through the rests, dd, and press against the ends of the elliptic

spring, c. These rods are shewn by g' g', Fig. 6. The connexion of the two buffers, hh, with the spring, is more complex. Two levers, i i, are fixed upon the frame, to one end of each of which the buffers are connected by the rods, ll; the other ends of the levers being connected, by a short link, to the ends, dd, of the spring. The connecting rods, ll, running in an oblique direction from the line of the buffer heads, the latter is kept parallel with the frame by a rod, sliding through the guides, kk. A similar apparatus is fixed to each carriage of the train, part of one of which is shewn in the plate.

When, therefore, a carriage is dragged in the direction of the two darts, the jerk occasioned by the pull of the engine is resisted, or neutralised, by the chain b, and rod b', Fig. 6, Plate VI., acting against the spring at c; the carriage being, in fact, put into motion by the ends of the spring, c, acting against the rests at dd. The carriage, B, is then put in motion by the ends, dd, of the spring, acting through the diagonal rods, e' e', to the chain, f; and the same apparatus, being fixed to the carriage в, it will be seen, that each carriage is put in motion by the action of two springs, viz. that upon the carriage itself, and also by the spring upon the carriage next preceding it. The chain, b, it ought to be remarked, is attached to a spring upon the tender, so that this carriage, also, is acted upon by two springs. The above contrivance effectually operates to prevent the blows or jerks to the carriages, by a sudden increase of velocity, or when the train is put in motion. We shall now explain how it operates against shocks, or blows, occasioned by any sudden diminution of velocity, or when the train is stopped. When a train is stopped, or the velocity is diminished, the inertia of the car

riage, immediately following the engine, causes it to run against the tender frame, and each carriage to strike against that next before it, or the buffers, n n, to strike against the buffers, h h. When the buffers, hh, are

struck against, they are pressed forward, and act against the ends, dd, of the spring, through the rods, 17, and cross heads, ii; at the same time, the buffers, nn, or, which has the same action, the buffers, gg, act, through the rods g'g', against the ends, dd, of the spring. Thus, either in pulling, or pushing the carriages; or in any variation or change of velocity, the spring, a a, acts to prevent any jerk, or blow, to the body of the carriage, and any unpleasant shock to the passengers. Several other methods have been adopted of applying similar elliptic springs. In some cases another elliptic spring has been applied to the back of d d, in the middle of the frame, in which case the dragging chain, f, and buffer heads, hh, work precisely the same as the chain, b, and buffer heads, g g, on the other end of the carriage; and this, indeed, seems to be a better application than the one in the drawing, as the cross heads, ii, and the oblique rods, e e and 11, are done away with, and the force applied more direct from the dragging chains and buffers to the springs, than in the other plan.

The wood engraving, Fig. 1, opposite, will shew this mode of applying the springs; a a and a' a', will be the two springs, placed back to back against the cross sheth, ss. At dd, in this plan, there would be rests, as in Fig 6, Plate VI.; and the rod, b b', would be applied to the spring, a a; and the rod, ff', to the spring, a' a'. The carriage would, in this plan, be dragged by the rests, dd, through the intervention of the spring, a a, in one direction, and by the rests, d' d', through the spring,