ALTHOUGH it has been a matter of about one hundred years since the idea of the internal-combustion engine entered the mind of the inventor, the practical application of its use was not attained till 1860, when Lenoir produced an engine similar to the ordinary high-pressure steam engine, with the valves arranged to admit the explosive mixture and the discharge of the exhaust gases. In this case no attempt was made to compress the gas before ignition, as it was then considered that the explosion under these conditions had a detrimental effect, inasmuch as it would act as a sudden blow to the working parts. Indeed, he went so far as to inject steam and water sprays to reduce the explosion. Under these conditions the consumption of gas was exceedingly high-about 106 cub. ft. of coal gas per b.h.p. per hour-but the mechanical effect showed that the engine ran in every respect as smoothly and quietly as in best steam-engine practice.