Mr. George Vaughan, of Mile-end Old Town, took out a patent in 1830 for a double-acting pump, acting in a horizontal direction; the principle of its operation may be readily understood after the description of the foregoing, and by comparing it to a high-pressure steam engine, with such difference only as to adapt it better to the pumping of water. The working chamber is either cylindrical or square; but each end of it is considerably enlarged downward, where the valves that receive the water from the rising main are situated. The piston is solid and packed like those for steam; the piston-rod passes through a stuffing-box at one end of the chamber, and is attached, at the farthest extremity, to a cross head, to which is connected two spear-rods. One of these rods passes on each side of the pump, and beyond the opposite end of it, to a crank, which is made to revolve in plummer blocks (fixed to a suitable frame), and is turned either with a winch, by manual labour, or by any other suitable power. The motion thus described is, of course, nothing but the ordinary parallel motion.

In order that the piston may not, by its weight, wear most on its under side, the piston-rod is continued on both sides of it; and beyond the range of the piston, the rod is supported by an anti-friction wheel; thence the rod enters a tubular case, closed at the furthest extremity to prevent the escape of the water, as it is not packed. The action of the pump is this: suppose, by the revolution of the crank, the piston to be moving to the right hand, a vacuum is produced on the opposite side of the piston, which causes the valve from the rising main to be opened by the pressure of the atmosphere, and the chamber is thereby filled with water. On reversing the stroke of the piston, or towards the left, the right-hand valve is opened from the rising main, and that end of the chamber filled with water, while the water which previously occupied the left end of the chamber is forced out by the piston through another valve on the upper side; the succeeding stroke in like manner discharges the water in the right chamber, and fills that of the left, and thus the action is continuous.

In the drawing attached to the specification, a large semi-cylindrical wheel is shown as fixed to the upper side of the pump, for the reception of the water delivered through the upper valves, and in the crown of the arch is a pipe for conducting the water, if required, to a greater elevation.

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It would obviously have been better, had the patentee made the upper part of this vessel into an air-chamber, by causing the ascending-pipe last mentioned to dip nearly to the bottom of it.

The annexed engraving is a representation of a pump constructed by Mr. Clymer, on the plan of the ingenious Benjamin Martin; but the suction-pipe and the valves are so disposed as to retain any heavy bodies that may be raised by the pressure of the atmosphere acting upon the vacuum.

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The above perspective sketch shows that the rising main leads into a spacious valve-box, in connexion with two short and wide working-barrels, left open to the atmosphere. The piston-rods are attached to a lever, vibrating on a central fulcrum which is mounted upon a standard between the two cylinders; and to this lever branching handles are united, to enable many hands to be employed in working it The large volume of water discharged from the barrels at each stroke of the pump causes a constant powerful stream up the rising main, so that any globular substances nearly fitting it, as cannon balls, have no opportunity to fall down by any intermission of pressure from underneath; they consequently get lodged in the valve-box, and are ejected by the down-stroke of the Sump. When employed as an engine to discharge water to a great height or distance, an air vessel is screwed on, as represented, and the nozzle is then plugged or capped, by which the current is directed through the air vessel.

In drawing water from great depths, the weight of the pump-rods and the water together are sometimes more than can be easily accomplished by the power at command; in such cases we have occasionally observed, in country places, a very simple apparatus, similar to that represented in the following cut, employed to counterbalance the weight of the rods. In this case, the pump-rod and handle is suspended to a wooden spring, of sufficient elasticity to sustain the weight of the rods, and to require a part of the man's force to depress the piston or bucket, in return for which the spring assists him in the pull upwards. Some persons would be apt to imagine that power was thus gained; but a little consideration will enable them to perceive that it is only by a different distribution of the same force that the desired effect is produced.

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In Dr. Gregory's Mechanics, vol. ii. is the following description of a pump, with little friction, which may be constructed in a variety of ways by any common carpenter, without the assistance of a pump-maker or plumber, and which will be very effective for raising a great quantity of water to small heights, as in draining marshes, marl-pits, quarries, etc, or even for the service of a house. It is exhibited in the subjoined diagram, where abcd is a square trunk of carpenter's work, open at both ends, and having a little cistern and spout at top. Near the bottom there is a partition made of board, perforated with a hole e, and covered with a clack; ffff represent a long cylindrical bag, made of leather or of double canvass, with a fold of thin leather, such as sheep-skin, between the canvass bags. This is firmly nailed to the board e, with soft leather between; the upper end of this bag is fixed on a round board, having also a hole and valve. This board may be turned in the lathe with a groove round its edge, and the bag fastened to it by a cord bound tight round it. The fork of the piston-rod is firmly fixed into this board; the bag is kept distended by a number of wooden hoops, or rings of strong wire f f, f f, f f, etc. put into it, at a few inches distance from each other.