A gas engine is a heat engine in which the working fluid is atmospheric air and the fuel an inflammable gas.
The efficiency of any form of heat engine is determined by the power obtained from a certain fuel consumption.
You have to have a fall of temperature to run any kind of heat engine.
Considered as a heat engine, the gas engine is now twice as efficient as the very best modern steam engine.
Considered as a heat engine, the efficiency of the most economical steam motor is but ten per cent.
What each one should consume is eminently individual, depending altogether on the sort of heat engine that each one is.
In this view, the muscular apparatus is a species of heat engine.
Thus it appears that we have been able to show by very definite experimental evidence that the radiometer is a heat engine.