During the process, the returning stroke of the beam and the vessel r has shifted the slider v from the mouth of the pipe j upon the mouth of u, and by the same opera tion formerly described, the rod in and the end n of the beam are raised, by which means the end z descends and places the cap jz on the top of its cylinder, and the gas in the cylinder a turns and raises the water into the cylinder in the manner already described.
In order to raise the caps off their respective cylinders a and b, after a vacuum has been made in them, a small quantity of air is admitted by a slide valve in the air pipe A, which is worked by chains BB attached to the floats t x, and by means of the lever z z to which the slide above A is attached, the ascent and descent of the floats admits the air alternately into the cylinders a and b immediately after the water is risen.
The gas is turned off and on by chains C, C, with sus pended weights, passing from the ends of the vessel r to the stop cock in the gas pipe f. The water raised by the engine is retained by the valves at D, D, and it occupies the mains and the outer cases of the cylinders which keeps the interior cool ; but the greater portion of the water that is received into the cylinders a, b, off through pipes EE to the trough F, from which it is delivered through a sluice into the buckets of a water wheel GGC, which it drives, and from the axle of which any kind of machinery may be driven. This wheel is unnecessary when the machine is to act merely as a pump.
The inventor remarks, that a piston may be worked on the principle of producing a vacuum beneath it by burning the air in the manner above described ; and he proposes that this be done in a distinct vessel, so as to communicate with several cylinders, and consequently to work several pistons at once; the air and vacuum valves being opened and shut by the same means as the induction and eduction valves in steam engines.
Mr. Brown proposes to impel steam boats with this engine, which, he says, will require only a few butts of oil for a long voyage.
Among the advantages of this engine are its small size, which is only one-fifth the weight of a steam engine and boiler of the same power, and its entire freedom from danger. See Dr. Brewster's Journal of Science, vol. i. p. 337.
The Rev. Mr. Cecil has described in the Cambridge Transactions, vol. i. part. ii. an engine in which a vacuum is created by the explosion of a mixture of hydrogen and common air. Mr. Cecil suggested in his paper that the expansive force of the explosion might also be employed.
24. Description of Mr. Hunter's Self-acting Pump.
This pump, invented by Mr. Hunter of Thurston, is founded on the same principles as the Hungarian machine, which we have already described in our article HYDRODY NAMICS. The object of it is to raise water above the original reservoir, by the descent of a certain portion of it. It is represented in Plate CCCCLXXI. No. I. Fig. 12, where A is the cistern filled by the spring B, C the cistern at which the water is required, and D a water-proof metallic box, twelve inches square, and four inches deep.
placed within A, and near the top of it. A pipe F, of half an inch bore, leads from the top of A to the bottom of F, which is a metallic box similar to D. A pipe G of half an inch bore, leads from the top of the box F to the top of D, the upper part of it being above the level of B. Another pipe H, of half an inch bore, leads from the bottom of D to the bottom of C, and is made as long as from R to S. One valve I opening upwards, is placed at the mouth of the pipe H, another K opening upwards at the bottom of D, and a third L opening upwards at the bottom of F. A pipe M conveys the overflowing water of E to a small light pan N, which, when filled with water, presses down one end of a lever 0, which opens the valve L. A flat piece of leather at the end of a chain, is suspended from the pan P, and that piece of leather opens a hole at A, when the arm 0 and pan N are forced down. The hole Q must be of a suffi cient size to let the water escape from the pan N, in the same time that D is filling with water through the valve K.
When the vessels D and F are full of air, the water flows from A into E, drives out the air from F, passes through G and D to I, and from E, F, and G, to the level of B. It then flows over at R into the pipe M, fills N, which descending by the weight of the water round the fulcrum ,f opens the hole Q, and the valve L as formerly described. The vessel F then empties itself at L, is filled with air from D through G, and D is filled with water through K. At the same time N is emptied through Q and returns to its place, allowing L to shut, and leaving F and G full of air. The water continues to rush through F, expelling the air from F through G at D, which air again expels the water from D through H up to C, until F and G are filled with water, and 0 with air, when the machine has returned to the same state as at the commencement of the operation, F and G being filled up to the level of B.
If it is desired to supply a house with water at the level et the middle story, the vessel may be placed in the kitchen, and C in the bed-room, and every gallon of water under the kitchen will give nearly a gallon in the bed-room. The pipe F may be supplied with impure or even dirty water; and in that case, the whole of the spring water of B will be doubled to C, instead of half of it being wasted at L ; so that the whole of any spring may be raised by forming a dam as in mills, and obtaining a fall for a part of the water equal to the height to which it is required to pump up the spring. The effect will be the same, whether R is on a level with B or not. The water will always rise as high above D, as R is from S. The superiority of this pump arises from its acting with very little friction, and, as a proof of this, it may be mentioned, that Mr. Hunter had a small one which wrought, without being touched, for three months, raising eight hogsheads of water every day.