space between them to be filled with water or other dense fluid capable of sufficient resistance, the force of one piston will act on the other just in the above proportion, viz. as 1 is to 2304. Suppose the small piston in the Injector to be forced down when in the act of pumping or injecting water into the cylinder A, with the power of 20 cwt. which could easily be done by the lever H; the piston B would then be moved up with a force equal to 20 cwt. multiplied by 2304.

Thus is constructed a hydro-mechanical engine, whereby a weight amounting to 2304 tons can be raised by a simple lever, through equal space, in much less time than could be done by any apparatus constructed on the known principles of mechanics; and it may be proper to observe, that the effect of all other mechanical combinations is counteracted by an accumulated complication of parts, which renders them incapable of being usefully extended beyond a certain degree; but in machines acted upon or constructed on this principle every difficulty of this kind is obviated, and their power subject to no finite restraint. To prove this, it will be only necessary to remark, that the force of any machine acting upon this principle can be increased ad infinitum, either by extending the proportion between the diameter of the cylinder A, or by applying greater power to the lever H.

Fig. 290 represents the section of an engine, by which very wonderful effects may be produced instantaneously by means of compressed air. A A is a cylinder with the piston B fitting air-tight, in the same manner as described in fig. 289. C is a globular vessel made of copper, iron, or other strong materials, capable of resisting immense force, similar to those of air-guns; D is a strong tube of small bore, in which is the stop-cock E. One of the ends of this tube communicates with the cylinder under the piston B, and the other with the globe C. Now, suppose the cylinder A to be the same diameter as that in fig. 289, and the tube D equal to one quarter of an inch diameter, which is the same as the injector, fig. 289; then, suppose that air is injected into the globe C (by the common method) till it presses against the cock E with a force equal to 20 cwt. which can easily be done; the consequence will be, that when the cock E is opened, the piston B will be moved in the cylinder A A with a power or force equal to 2304 tons; and it is obvious, as in the case fig. 289, that any other unlimited degree of force may be acquired by machines or engines thus constructed. Fig. 291 is a section, merely to show how the power and motion of one machine may, by means of fluids, be transferred or communicated to another, let their distance and local situation be what they may. A and B are two small tubes, smooth and cylindrical, in the inside of each of which is a piston, made water and air tight, as in figs. 288 and 289. CC is a tube conveyed under ground, or otherwise, from the bottom of one cylinder to the other, to form a communication between them, notwithstanding their distance be never so great, this tube being filled with water or other fluid, until it touch the bottom of the piston; then, by depressing the piston A, the piston B will be raised. The same effect will be produced vice versá: thus bells may be rung, wheels turned, or other machinery put invisibly in motion, by a power being applied to either.

Fig. 292 is a section, showing another instance of communicating the action and force of one machine to another; and how water may be raised cut of wells of any depth, and at any distance from the place where the operating power is applied. A is a cylinder of any required dimensions, in which is the working piston B, as in the foregoing examples; into the bottom of this cylinder is inserted the tube C, which may be of less bore then the cylinder A. This tube is continued, in any required direction,

down to the pump cylinder D, supposed to be fixed in the deep well EE, and forms a junction therewith above the piston F; which piston has a rod G, working through the stuffing-box, as is usual in the common pump. To this rod G is connected, over a pulley or otherwise, a weight H, sufficient to overbalance the weight of water in the tube C, and to raise the piston F, when the piston B is lifted; thus, suppose the piston B is drawn up by its rod, there will be a vacuum made in the pump cylinder D, below the piston F; the vacuum will be filled with water through the suction pipe, by the pressure of the atmosphere, as in all pumps fixed in air. The return of the piston B, by being pressed downwards in the cylinder A, will make a stroke of the piston in the pump cylinder D, which may be repeated in the usual way by the motion of the piston B, and the action of the water in the tube C. The rod G of the piston F, and the weight H, are not necessary in wells of a depth where the atmosphere will overbalance the water in the suction of the pump cylinder D, and that in the tube C. The small tube and cock in the cistern I, are for the purpose of charging the tube C.

By these means it is obvious that the most commodious machines, of prodigious power, and susceptible of the greatest strength, may readily be formed. If the same multiplication of power be attempted by toothed wheels, pinions, and racks, it is scarcely possible to give strength enough to the teeth of the racks, and the machine becomes very cumbersome and of great expense. But Mr. Bramah's machine may be made to possess great strength in very small compass. It only requires very accurate execution. Mr. Bramah, however, was greatly mistaken when he published it as the discovery of a new mechanic power. The principle on which it depends has been well known for nearly two centuries; and it is matter of surprise that it has never before been applied to any useful practical purpose.

5. The Stanhope printing-press is delineated in figs. 293 and 294, being elevations, and fig. 295, a plan.

AA is a massive frame of cast-iron formed in one piece; this is the body of the press, in the upper part of which a nut is fixed for the reception of the screw b, and its point operates upon the upper end of a slider d, which is fitted into a dove-tail groove formed between two vertical bars ee, of the frame. The slider has the platen DD firmly attached to the lower end of it; and being accurately fitted between the guides ee, the platen must rise and fall parallel to itself when the screw b is turned. The weight of the platen and the slider are counterbalanced by a heavy weight E, behind the press, which is suspended from the lever F, and this acts upon the slider to lift it up, and keep it always bearing against the point of the screw.

At G are two projecting pieces, cast all in one with the main frame, to support the carriage when the pull is made; to these the rails H are screwed, and placed truly horizontal, for the carriage I to run upon them, when it is carried under the press to receive the impression, or drawn out to remove the printed sheet. The carriage is moved by the rounce or handle K, with a spit and leather girts very similar to the wooden press. Upon the spit or axle, a wheel, L, is fixed, and round this leather belts are passed, one extending to the back of the carriage to draw it in, and two others, which pass round the wheel in an opposite direction, to draw it out.

By this means, when the handle is turned one way it draws out the carriage, and by reversing the motion it is carried in. There is likewise a check strapf, from the wheel down to the wooden base M, of the frames, and this limits the motion of the wheel, and consequently the excursion of the carriage.

The principal improvement of Earl Stanhope's press consists in the manner of giving motion to the screw, b, of it, which is not done simply by a bar or lever attached to the screw, but by a second lever e, g; the screw, b, has a short lever, g, fixed upon the upper end of it, and this communicates by an iron bar, or link, h, to another lever, i, of rather shorter radius, which is fixed upon the upper end of the second spindle 1, and to this the bar or handle, k, is fixed. Now when the workman pulls this handle, he turns round the spindle 7, and by the connection of the rod, h, the screw, b, turns with it, and causes the platen to descend and produce the pressure. But it is not simply this alone, for the power of the lever, k, is transmitted to the screw, in a ratio proportioned to the effect required at the different parts of the pull; thus at first, when the pressman takes the bar K, it lies in a direction parallel to the frame, or across the press, and the short lever i (being nearly perpendicular thereto) is also nearly at right angles to the connecting rod h; but the lever, g, of the screw, makes a considerable angle with the rod, which therefore acts upon a shorter radius to turn the screw; because the real power exerted by any action upon a lever, is not to be considered as acting with the full length of the lever between its centres, but with the distance in a perpendicular drawn line, in which the action is applied to the centre of the lever. Therefore when the pressman first takes the handle K, the lever i acts with its full length upon a shorter length of leverage, g, on the screw, which will consequently be turned more rapidly than if the bar itself was attached to it; but on continuing the pull, the situation of the levers change, that of the screw, g, continually increasing its acting length, because it comes nearer to a perpendicular with the connecting rod, and at the same time the lever i, diminishing its acting length, because, by the obliquity of the lever, the rod, h, approaches the centre, and the perpendicular distance diminishes; the bar or handle also comes to a more favourable position for the man to pull, because he draws nearly at right angles to its length.

All these causes combined have the best effect in producing an immense pressure, without loss of time; because in the first instance the lever acts with an increased motion upon the screw, and brings the platen down very quickly upon the

paper, but by that time the levers have assumed such a position as to exert a more powerful action upon each other, and this action continues to increase as the bar is drawn forwards, until the lever, i, and the connecting rod are brought nearly into a straight line, and then the power is immensely great, and capable of producing any requisite pressure which the parts of the press will sustain without yielding. The handle is sometimes made to come to rest against a stop, which prevents it moving further, and therefore regulates the degree of pressure given upon the work: but to give the means of increasing or diminishing this pressure, for different kinds of work, the stop is made movable to a small extent. A better plan is adopted by some makers of the Stanhope press, viz. to have a screw adjustment at the end of the connecting rod h, by which it can be shortened; it is done by fitting the centre pin which unites it to the lever g, in a bearing piece, which slides in a groove formed in the rod, and is regulated by the screw. This shortening of the connecting rod produces a greater or less descent of the platen, when the handle is brought to the stop.

The carriage of the press is represented with wheels, m m, beneath, to take off the friction of moving upon the ribs H. These wheels are shown at fig. 296, which is a section of the screw and the platen, with the carriage beneath it; and fig. 297 is a plan answering to it. Fig. 298 is a figure of a carriage inverted to show the wheels; then axles n are fitted to springs p, and these are adjustable by means of screws r, so that the carriage will be borne up to any required height. This is so regulated, that when the carriage is run into the press, its lower surface shall bear lightly upon the solid cheeks G, which are part of the body of the press, and these support it when the pressure is applied, the same as the winter of the old press; but the wheels by their springs act to bear up great part of the carriage with the types upon it, and diminish the friction, yet do not destroy the contact of the carriage upon the ribs, because this would not give the carriage that solidity of bearing which is requisite for resisting the pull. This is only at the time when the carriage is run into the press; because as it runs out, the ribs on which the wheels run rise higher, and therefore the wheels support the whole weight.

The manner in which the wheels run in rebates or recesses in the edges of the ribs, is shown at fig. 294. The carriage is made of cast-iron, in the form of a box, with several cross partitions, which are all cast in one piece, and though made of thin metal, are exceedingly strong; the upper surface is made truly flat, by turning it in a lathe. The same of the platen, which is likewise a shallow box; the slider d has a plate formed on the lower end of it, which is fixed by four screws upon the top of the platen, and thus they are united.

At the four angles of the carriage, pieces of iron, r, fig. 297, are screwed on, to form bearings for the quoins or wedges which are driven in to fasten the form of types upon it in the true position for printing. The tympan P, fig. 293, is attached to the carriage by hinges, with an iron bracket or stop to catch it when it is thrown back; the frisket, R, is joined to the tympan,