Page:Popular Science Monthly Volume 12.djvu/271





45. engines of Hero and Branca were, it will be remembered, non-condensing; but the first plan of a non-condensing engine that could have been made of any really practical use is given in the "Theatrum Machinarum" of Leupold, published in 1720. His sketch is copied in Fig. 23. It is stated by Leupold that this plan was