He gives the first as Fig. 150, "A Water Screw," the purpose of which is not quite so obvious as to be understood at the first view of the figure; for the inventor intimates that he intends it for a perpetuum mobile. He has, however, scarcely worked out his purpose, as we may, nevertheless, say without any prejudice to the inventor. Nor will we here describe how the excellence of this work consists in the proportion and distribution of the wheel, and the balls or weights, because it is our intention to publish, at a future time, a separate treatise on the perpetuum mobile, in which we shall consider this and several similar machines. Figure 151 is "A Water Screw," having a grindstone for cutlery. The author remarks concerning this machine as follows: [Illustration] This machine also is intended for a perpetuum mobile. The inventor discharges water from the reservoir A, by the canal B, on the water-wheel C, which turns the open screw-cylinder D, by means of the toothed wheel E, the cog-wheel F, the spoked wheel G, together with the cylinder H, and the spoked wheel I, whilst this spoked wheel I, catching the small cog-wheel L, together with the cylinder M, and the handle R, turns the small spoked wheel of the screw-cylinder H, and the screw-cylinder itself, and thus draws up again the water discharged from the reservoir A through the spiral screw Q. In order to render this machine useful, a couple of grindstones are placed on the cylinder D. Concerning this machine, it is particularly to be considered, whether a sufficient amount of water can be raised again, as has been frequently remarked before about similar works. Figure 152 is said to represent "A Double Water Screw, with Double Pump," and the author observes: This machine is, on the whole, similar to the preceding ones. The water is discharged from the round or square reservoir A, by B, on the water-wheel C. A continual supply of water for the water-wheel is provided as follows: The crown wheel H is fixed on the upright cylinder M, and is turned by the revolutions of the cylinder, whilst it turns at the same time the upper wheel L, which, acting on the spokes of the double screw K, K, draws up sufficient water by I, I, and then, as stated, discharges it by B, on the wheel C. The machine may be rendered useful by furnishing the cylinder D with the double crank E, to drive the two pistons of the tubes F, F, which lift the water through the pipes G, G, into the reservoir N, whence it may be carried off for service. [Illustration] John Linley's Hydraulic Device. 1831 An account of this was published in 1831 in Mechanics' Magazine, and is as follows: 32. Perpetual Water-wheels and Pumps (vol. 14, 1831).--A correspondent gives a description of a plan which he says he believes to be entirely original, and not without considerable claims to plausibility, thus: [Illustration]