Page:The South Devon Atmospheric Railway.djvu/8

 By, Past-President,.

Leaving out of consideration Savory's and such like machines for the raising of water by means of a partial vacuum produced by the condensation of steam— the first suggestion, so far as the writer is aware, for transmitting energy by the rarefaction of air, was made by Denis Papin, who, in 1695, published in Cassel a book called "Recueil de diverses pieces touchant quelques nouvelles machines," where, at page 36, is to be found the description of the drawing, Fig. 1, page 300.

Without repeating Papin's minute description, it will suffice to say that the waterwheel Q, by means of the double-throw crankshaft P, worked two exhausting pumps T T, from which proceeded the common exhaust-main E to the place where the power was required to be developed. Here there were two open-topped working cylinders 1 1, containing pistons H G, on the under side of each of which a partially vacuous condition was, from time to time, to be made by connecting their respective pipes N and M alternately with the exhaust main E and with the atmosphere, by the operation of the central cock S. The pistons had ropes E and F attached to their upper sides; these ropes were wound in reverse directions around the axle D, which axle carried the large grooved wheel A, having over it the rope B, at each end of which were the buckets C, to raise the water.