All About Inventions and Discoveries
The Romance of modern scientific and mechanical Achievements

198 All About Inventions gave the world a new means of generating power which changed completely our conditions of industry and locomotion, inasmuch as their ideas culminated in Stephenson’s invention of the locomotive and of the steamship. Yet the rotary engine has always possessed an indescribable fascination for inventors, comparable with the search for perpetual motion ; and, up to the dawn of the ’eighties of the past century, just about as much success was recorded in the former as in the latter field of thought and experiment. The rotary engine differs from its rival very radically. In the steam-engine devised by Newcomen and Watt, and the fundamental features of which remain to this day, the steam is admitted into a cylinder in which moves a piston. The pressure, or expansive properties of the steam, drive the piston back to the limit of its travel in the cylinder. Attached to this moving piston is a long rod, the piston-rod, the oppo- site end of which is attached to a crank, set at right angles to the piston-rod. The movement of the piston communicated through the rod revolves the crankshaft, to which a flywheel, acting as a reservoir of energy, is mounted. From this flywheel the power may be distributed to other machinery through a suitable medium, such as gearing, belt, chain, or by friction. When the piston has reached the limit of its back- ward travel steam is admitted behind it, thereby driving it forward. This action not only gives another boost to the crank and flywheel, but serves to drive out of the cylinder the steam which was first admitted and has completed its work. A fresh supply of steam enters the cylinder at its forward end, driving the piston back once more, this alternate introduction of