the reservoir C, from which it is raised again by the fountains into the upper cistern E; and so on as long as you please, or as long as the whole keeps in repair and in good order. The apparatus may, with facility, be stopped for convenience at any time without fear of derangement, because the fountains carrying water faster than it escapes from the lower orifices, the cisterns will be always full; and it may be again set in motion with equal facility. With the above proviso, it cannot stop till the prevailing natural causes which gave it motion--viz., the pressure of the atmosphere and the descent of water, which in their nature and tendency are of themselves perpetual--shall be diverted. Thus you may have the power, free and disposable, of three water-wheels in perpetual motion, to be applied to such useful purposes of machinery within the building as its inmates may require. A supply of water-mills might be thus provided in any situation--in the center of the metropolis or other large towns--in places subject to a deficiency of rivulets suitable for mills on the common system. Neither would there be any necessity for resorting to rivers, or raising immense buildings upon their banks; wherever there was a convenient house, it might be readily appropriated with little further expense than machinery. Yours, etc., ED. "VOCIS RATIONIS." Jan. 10, 1831. Böckler's Plates In 1662 George Andrew Böckler published a work on mechanics. The work is replete with fine drawings. Not a great deal of space is devoted to Perpetual Motion devices, but the following three plates which are numbered 150, 151 and 152 in his work are shown as Perpetual Motion devices. These devices do not appear to have been the inventions of Böckler himself, but are devices noticed by him. They are not explained with any considerable detail. [Illustration] Figure 150 is "A Water Screw," and it is stated that the inventor intends it for a Perpetual Motion device, and it is further stated that he has scarcely worked out his purpose. The author states that the excellence consists in the proportion and distribution of the wheel, balls and weights, and says further that he does not describe it in detail, and that it is his intention to publish at a future time a separate treatise on Perpetual Motion in which this and other similar machines will be considered.