This Machine is represented in [Plate 8], [fig. 2 and 3]. It is composed of two barrels A B, both of them forming part of the column of water to be raised; connected together by a crooked tube C, of equal diameter, out of which the lower Piston-rod passes through a stuffing box into the air: as does the upper Piston-rod at D, where the column leaves the Pump to pass upward. The two Pistons fixed to the rods E and F, are of the bucket kind; made as thin and light as possible; their valves opening upwards and their motions being such, generally, that when one of them is drawn up, the water rises through the other, then descending: But here lies both the novelty and utility of this Machine; these upward and downward motions are not reciprocal: Both Pistons fall faster than they rise, and thus leave an interval of time when they both rise together; during which their valves, respectively, close by their own weight before the column of water falls upon them. In such manner, indeed, that the column never falls at all. By this important arrangement, the work is constantly going on, and no commotion occurs to absorb Power uselessly, or to destroy, prematurely, the Machine; circumstances which constantly attend every Pump Machine acting by merely reciprocal motion.
This non-reciprocity then, I produce by several methods; one of which (perhaps the most easily understood) is that shewn in [fig. 2]: There, A B are two friction-rollers, made as large as possible, rolling on the curves C X, the ascending and descending parts of which are essentially unequal. For example, the rising part of the curve occupies 2⁄3 of the whole circumference; and the falling part 1⁄3 only; so that both curves recede from the centre at the same time, during 1⁄6 of a revolution, at the two opposite positions, A C and X Y. Applying then, these curves and levers to the Pump-barrels represented in [fig. 3], we obtain that continuity of uniform motion, which is necessary to doing the greatest quantity of work with the least power; and to securing the greatest durability of the Machine. Having hinted at a minimum of power, I must add here that this Machine appears to promise that result, much more credibly than any reciprocating pump whatever; especially if to this continuity of motion we add a certain largeness of dimension that shall produce the required quantity of water, with the slowest possible motion of each particle; and even here this continuative principle helps us much; since pistons and valves of the largest dimensions may be used without introducing any convulsive, or (what is synonymous) any destructive effects.
One particular remains to be noticed in [fig. 2]. It relates to the means by which the perpendicularity of the motion in the Piston-rods is secured. The arcs M are portions of cylinders having the bolts Z, for their centres, and which, rolling up and down against the perpendicular plane O N, secure a similar motion to the bolts. The tenons P, are cycloidal, on their upper and lower surfaces; and work in square or oblong holes in the plane N O, being kept in their holes by the action of the two springs on a pin let through these tenons: and thus is the motion of the point Z of the levers M B, a perpendicular one; and that of the friction rollers A B, very nearly so.
My object in this work, is to make known the principles, and some of the forms of these Inventions, but my limits will not permit their being dilated on; else I could give several more useful forms of this Machine: but, to make room for other subjects, I must hasten forward—reserving to some future period, many hints respecting the adaptation of those ideas to particular cases. Those of my readers who love to speculate on the doctrine of permutations, will anticipate how much may be done by the combination of a hundred Machines with each other: and they will give me credit for detached items of knowledge—useful in themselves, though too minute to be severally brought forward. Should, however, the degree of patronage I have already experienced, be proportionably extended as the work advances, I can and will follow it up with many useful hints, tending to shew the extent of some of my present subjects, and the amplitude of the sphere in which they roll.
It should be observed, in concluding this article, that the present Machine was executed in France, in 1793, and also proposed to the Government, as a substitute for the celebrated Machine of Marly. In the report then published, it was preferred to the whole multitude of former projects; but left in equilibrio with one modern Machine,—a competition which prevented it’s adoption for the moment—and indeed till I was glad to escape the notice, instead of courting the favour of the then rapidly succeeding governments.