sisted only in the use of steam-boilers instead of air-heaters. The English writer is here incorrect, as she was supplied with steam-boilers and engines.
The Ericsson made a trip from New York to Washington, and is said to have used an enormous quantity of tallow in lubricating her machinery.
This difficulty is avoided in some of the smaller machines now built, by saturating the air with steam.
See Aero-steam engine.
In a paper read by Mr. Rankine before the British Association in Liverpool, September, 1854, is a succinct statement of the principles underlying this subject of invention; from it we derive the following: —
Heat acts as a source of mechanical power by expanding bodies, and conversely, when mechanical power is expended in compressing bodies, or in producing friction, heat is evolved.
This mutual convertibility of heat and mechanical power is expressed in the following law: That when mechanical power is produced by the expenditure of heat, a quantity of hea