Note 45 — Chapter I

The now well-known principle of a steam-engine is this: there is a cylinder with its rod fixed to one end of a lever, which is worked by the combined pressure of the atmosphere and the steam upon a piston, a temporary vacuum being made below it by suddenly condensing the steam, which had been let into the cylinder where this piston works, by a jet of cold water thrown into it. A partial vacuum being thus made, the weight of the atmosphere presses down the piston and raises the other end of the straight lever, thereby drawing up water from a mine, or, by the numberless improvements made of late years, communicating a mechanical power which may set in motion every description of machinery.