Figures 1 and 2.—A, A, the uprights, erected on the frame, a, and supported by the braces, c; connected by the cross feet, a, at bottom, and the piece, n, at top; in this the pulley, b, tbr the rope, d, is fitted. Fillets of iron are fixed •ithinside the uprights, A, A, and enter grooves made in the edges of the great iron ram, E, which is thereby guided as it rises and falls : F iS a piece, called the follower (see Figures 3 and 4) consisting of a wooden block, sliding between the uprights, and mortised to receive the iron tongs, e, which take hold of an eye on the top of the cast-iron ram: the rope is attached to the follower by an iron hoop, f, through w hieh the centre pin of the tongs passes. On the base, a 13, of the machine, an iron frame is bolted, to contain the windlass, G, on which the rope, d, winds. On the end of the windlass a cog-wheel, g, is fixed, and a pinion upon the axis, h, engages its teeth. Motion is given to the spindle, h, by the winches, A-, fixed to each end of it, and the flywheel, 1, regulates its motion, when turned by two men at each handle. The pile is of course included in the space between the two uprights, A, A, before it is driven down; and the ram, being engaged by the tongs, e, is drawn up by turning the handle, A', till the tails, n, of the tongs come to the inclined planes, in, Figure 1: by these they are closed together, which opening the lower ends, disengages them from the eye of the ram, and it falls upon the head of the pile immediately. The men at the handles shift the spindle, h, endwise, which disengages the pinion from the wheel, and then the weight of the follower, F, runs back the windlass, G, and descends till its tongs take hold of the ram, ready to take it up again. The inclined planes, m, are not fixed to the uprights, A, A, but are connected together by pieces of wood, which embrace the uprights, and these have holes through them to receive iron bolts, which also pass through the uprights. By this means the inclined planes can be shifted, to set them at any required height, that they may, by dis charging the ram at the proper height, give a blow propor tioned to the pile to be driven. The tongs are sometimes made, with rollers in the ends, n, n, as shown in Figure 12, that they may act more easily in the inclined planes. Other machines have a kind of latch, shown in Figure 11, instead of the tongs ; in this,/ represents the iron loop for the rope; the centre pin of which, passing through the latch, r s catches the eye of the rain by the hook, t, and is discharged by the line r, when the men snatch it. The weight, s, is to cause the hook to catch ; and the loop, f, is attached to the wooden follower, which guides it between the uprights.
.Machines of this kind are frequently actuated by steam engines. A pulley, fixed on the end of the spindle, h, in place of the handle, A', receives an endless rope from some wheel put in motion by the engine ; one man then attends it, to throw the spindle endwise at the proper time, to permit the descent of the follower ; but we have seen one in which levers, and a connecting rod from the inclined plane, m, were used to disengage the spindle the moment after the follower discharges the ram ; by adopting these means much expense of labour would be saved, as the steam-engine which is after wards to be employed in pumping the water out of the coffer dams, would drive the piles for them and for the foundations.
The piles of the works of Westminster-bridge, whilst it was building, were driven by a horse-machine, invented by Mr. Valoue. A pair of the uprights, such as represented in Figures I and 2, but thirty feet high, were erected at one end of a frame, which supported a vertical shaft, turned round by the horses, and the framing was of course large enough to admit a circular walk of sufficient size for them to work in, when they drew the ends of arms or levers projecting from the vertical shaft. The whole was erected upon a plat
form, which was built over a barge in the manner of a deck. The vertical shaft had a wheel or drum upon it, to wind up the rope of the follower, and it was in the construction of this part that the invention lay. A section of the upper part of the vertical shaft and drum is given in Figure S, and a plan in Figure 9. Here A is the great upright shaft, or axle, turned by the horses attached to the levers, which are not shown. The cog-wheel, a, turns the pinion, x, having a fiy, o, at the top to regulate the motion, and to act against the horses, and keep them from falling, when the ram is disen The drum, c, is loose upon the axle of the shaft, A, but is locked to the wheel, 13, by the bolt, v. On this drum the great rope, is wound, one end of it being fixed to the drum, and the other to the follower, passing over proper pulleys. In the follower are contained the tongs, which take hold of the rain, by the staple for drawing it up, as described in Figure 2; n is a spiral, or fusee, fixed to the drum, c, on which winds the small rope, T: it goes over a pulley, and has a small counterpoise hung to the end of it, which hinders the follower from accelerating as it goes down to take hold of the rain ; for, as the follower tends to acquire velocity in its descent, the line, T, winds downwards upon the fusee on a larger and larger radius, by which means the counterpoise acts stronger and stronger against it ; and so allows it to come down with only a moderate and uniform velocity. The bolt, v, locks the drum to the great wheel, being pushed upwards by the small lever, 3, which passes through a mortise on the shaft, A, and turns upon a pin ; the lower end of the bolt is guided by passing through a piece of wood, fixed into the great shaft, and the upper end passes through an arm of the wheel; the lever, 3, has a weight, which always tends to push up the bolt, v, through the wheel into the drum ; c L is the great lever, turning on the centre, at, and resting its end, o, upon the forcing bar, 5, which goes down through a hollow in the shaft, A, and bears upon the little lever, 3. The other end of the lever, L, is long enough to reach the uprights, and has there a small rope, extended from its end up to the inclined planes, so that the follower, when drawn to the highest, pulls this rope, and raises the long end, L, of the lever, depressing the other, and forcing the bar, 5. By the horses going round, the great rope, n, is wound about the drum, c, and the ram is drawn up by the tongs in the follower, till they come between the inclined planes, which, by shutting the tongs at the top, open them below, and so discharge the rain, which falls down between the uprights and the pile, and drives it by a few strokes as far into the ground as it can go, or as is desired ; after which, the top part is sawed oil' close to the 'mid, by an engine for that purpose. Immediately after the ram is discharged, a piece upon the follower takes hold of the rope, which raises the end L, of the lever i. (1, and causes its end, o, to descend, and press down the forcing-bar, 5, upon the little lever, 3, which, by drawing down the bolt, v, unlocks the drum c, from the great wheel, and then the follower being at liberty, comes down by its own weight to the rain ; and the lower ends of the tongs slip over the eye of the rain, the weight of their heads causing them to fall outwards, and firsten upon it : then the weight, 4, pushes up the bolt, v, into the drum, which locks it to the great wheel, and so the ram is drawn up as before. As the follower comes down, it causes the drum, c, to turn back ward, and unwinds the rope from it, while the horses, the great wheel, the pinion x, and the fly, go on with an uninter rupted motion ; and as the drum is turning backward, the counterpoise is drawn up by its rope, T, winding upon the spiral fusee, D.