_Of another useful invention for raising water easily, by the which a certain Italian ventured to boast that he had discovered the Perpetual Motion._ DESCRIPTION OF THE INSTRUMENT.--A is an exhauster, or pump. [Illustration] B, a little wheel placed at the bottom of the exhauster, about which pestils, or circular flaps of prepared leather, revolve lightly, so that they rise easily: they are connected by crooked iron. C C C, pestils, or circular leathers, by means of which the water is raised in the pump. D, a wheel, by which the said circular leathers are raised up. E, a pinion, moving the wheels D and B. F is a wheel, continued from the wheel G, whose teeth the pinion E propels circularly. H, a pinion moving the wheel G. USE OF THE INSTRUMENT.--This instrument is classed with those of the first sort, on which account it is absolutely necessary for a multitude of purposes, because it bears upward a large quantity of water with the least labor; for the number of wheels is not variable; but the length of the receiver A is about the proportion of 35 feet, and its breadth one foot and one-third. The concavities of it should be made exactly round, that they may not lose any water by contracting in their ascension; the concavity of the pump, therefore, should be perfectly round. The great water-wheel should be 24 feet diameter, and the wheel G 20 feet. The Italian, deceived by his own thoughts, conceived that as much water would be raised by this pump as would keep the wheel perpetually in motion; because he said that more force was required at the extremity of this machine than at the centre; but because he calculated the proportions of power wrong, he was deceived in practice. P. Valentine Stansel's Device. Prior to 1657 (Exact date not known): [Illustration] A, B, C is a large cistern of water, above which is another cistern D, E, which is supplied from the lower cistern by the pump X, operated by the water-wheel M, N, the crank L of which is attached by a rod K to the horizontal beam H, I, K, which swings at H, from the side of the upper cistern, as shown at F, G, H. The force-pump X, on the depression of the plunger O, causes the water to rise up the vertical pipe P, Q, R, S, and thence discharge itself into the cistern D, from which a small portion is allowed to escape through the short pipe T, V, whence it falls on the water-wheel, and so on continuously. Vogel's Device In 1847, A. F. Vogel, of Leipzig, invented what he called "Hydrostatic General Mobile." It was described at the time in a pamphlet, and its operation is sufficiently illustrated by the following annexed figure and explanation: [Illustration]