The following engraving represents a perspective view of Newsham's engine, ready for working. It consists of a strong oak cistern, about three times as long as it is broad, mounted on four wheels, and drawn by the handle a. The under part of the cistern is cut away in front, to allow the fore-wheels to lock in turning round: the earliest engines were not furnished with this contrivance, but none are now built without it. At b is an inverted pyramidical case, enclosing the pumps and air vessel, forming a platform c, on which the fireman formerly stood to direct the jet of water issuing from the spout or branch pipe d. This branch pipe is attached to the air vessel by two brass elbows, the first of which is screwed on the top of the air vessel, and the second elbow screws upon the first by a fine screw of several threads, so truly turned as to be per fectly water-tight in every direction. The first elbow revolves on the top air vessel horizontally, while the second elbow revolves on the first the combination of these two motions, therefore, permits the branch pipe to be guided in every possible direction. This contrivance, however, is now obsolete, except in small garden engines, where it is used in an improved form. The flexible leather hose affords such a ready and convenient method of conducting the stream of water to any required point, that all fire engines are furnished with a proper quantity of it, to the extremity of which the branch pipe is attached. At the hinder part of the engine is seen a strong leather suction pipe (prevented from collapsing by a spiral piece of metal running throughout its length), one end of which is screwed on, when required, to a brass nozle at the lower end of the cistern ; the other end is furnished with a rose or strainer, and immersed in the water supplied by a pond, fire-plug, &c. To the hinder part of the cistern is added a wooden trough e, with a copper grating (for keeping out stones, sand, dirt, &c.) through which the cistern is supplied with water, when the suction pipe cannot be used. An open space is left in the fore part Of the engine, also furnished with a copper grating, through which water may be poured into the cistern. In working this engine, the handles ff, visible on each side, are moved up and down, which gives alternate motion to the two pumps. The working is also assisted by persons who stand on two suspended treadles g g, throwing their weight on each alternately as they descend, and keeping themselves steady by means of the two rails h h. The use of treadles, however, has been discontinued for some time, and they only now remain in a few of the oldest engines. Over the hied trough there is an iron handle or key i, which turns the auction cock (a three-way cock) situated beneath it. While the engine is working from water drawn through the suction pipe, the handle i stands in the direction of the cistern, as drawn ; but when the engine works from water contained in its own cistern, this handle is turned a quarter round, into the position shown by the dotted lines. Between the pyramidal case b and the fore end of the engine, there is a strong square iron shaft k, lying in a horizontal position over the middle of the cistern, lengthwise, and playing in brasses at each end, one of which is seen placed between the two uprights 11 supporting the hand-rails. Upon this shaft are fitted two stout iron bars or levers m m, one at each end, which carry the cylindrical wooden handles f f, by which the engine is worked. The treadles g g are suspended at the end by pitched chains, and receive their motionjointly with the handles that are on their respective sides, by means of iron double sectors fixed upon the shaft k; the foremost sectors are seen at n, the others are contained within the upright box b.
Jig. 2, in the subjoined engravings, is a section of the working parts of this engine through the cylinders, as seen on looking from the fore part of the cis tern towards the air vessel; o o are the working cylinders or pump-barrels ; pp the piston rods, with square holes to carry one end of the treadles ; q is the double sector connected with the piston rods by the chains before mentioned.
It will be seen that there are two chains to each piston, one passing from the top of the sector to the lower end of the piston rod; the other from the top of the piston rod to the bottom of the sector. The chains are riveted to the sectors, and attached to the piston rods by screw nuts, which allow them to be kept constantly tight. The pistons r r are formed of two round plates of brass, smaller in diameter than the barrels, put into stout leather cups, and fastened together by a nut, which screws on the piston-rod below the pistons ; sa in is a portion of one of the levers, by which the engine is worked ; the situation of the two entrance-valves is seen at the bottom of each cylinder. Fig. 3 is another section, taken vertically through the hinder part of the engine, showing one of the cylinders o and the air vessel s. On the floor of the cistern is placed the standing-piece, or sole, of cast-brass, which reaches from the nozle .r through the suction cock y, and afterwards divides itself into two branches, so as to open under each of the barrels ; one of these passages is seen in the figure, the other is situated exactly behind it ; through these channels water is conveyed to the pumps, either from the cistern itself, or from any place without, by means of the suction pipes. The two cylinders are screwed down upon the standing, or as it is frequently termed, the sucking piece, with plates of leather between" them, which makes the joints water-tight, and also forms the valves, one of which appears at t. Each cylinder has a projecting piece cast on its lower side, which forms a seat for the air vessel, and a communication into it, which is closed by a valve opening upward at v. The leather valves are kept closed, and also strengthened by a piece of metal having a tail, which passes through the leather, and is cross-pinned under it. When the engine is at rest, all four of the valves continue closed by their own weight ; but when the engine is working, two are opened and shut alternately. q is the sector on the shaft k, and g is one of the treddles in its bearing on the piston-rod ; s shows the internal construction of the air vessel. The action of this engine is exceed ingly simple ; on raising the piston r a partial vacuum is produced in the cylin der o, when the pressure of the atmosphere forces the water up the suction pipe through the cock y, along the sole, and lifting the valve t into the cylinder. Upon the piston reaching the top of its stroke, and beginning to descend, the valve t closes, and prevents the water, which has entered the cylinder, from returning by the way it came ; being urged by the forcible descent of the piston, it is driven along the communication into the air vessel, raising the valve a in its progress, which closes again the moment the water has all passed through. While this process has been going on, the other cylinder has become filled with water, which is now discharged in its turn into the air vessel, and so on continuously. On the water first entering the air vessel, a quantity of air is expelled ; but so soon as the water rises to the dotted line, the lower orifice of the exit pipe becomes covered, and the escape of any farther portion of air is prevented ; the air is therefore gradually by the continued influx of water into a much smaller space than it originally occupied, and by its elastic force reacting on the surface of the water, drives up the upright pipe s, along the leather hose, and out at the branch-pipe, with so great velocity as to break windows, &c., and throw up a jet to the height of sixty or seventy feet. New sham met with great encouragement, his patent being renewed for a second term ; his engines were eagerly purchased by the government, nobility, and gentry, the different parishes, and by the various fire insurance companies that were formed about this time ; viz. the Hand-in-Hand, in 1696 ; the Union, in 1714 ; and the London Assurance Corporation, in 1720.