Nikola Tesla U.S. Patent 517,900 - Steam Engine Patent Wrapper Page 6

78 TO ALL WHOM IT MAY CONCERN: BE IT KNOWN, that I, NIKOLA TESLA, a citizen of the United States, residing at. New York, in the County and State of New York, have invented certain new and us eful Improvements in STEAM ENGINES of which the following is a specification, reference being had to the drawings accompanying and forming a part of the same. 2: Heretofore, engines, operated by the application of a force such as the elastic tension of steam or a gas under pressure, have been provided with a fly-wheel, or sone rotary system equivalent in its effect and possessing relatively great mechanical inertia, which was relied upon for maintaining a uniform speed. urbring I have produced however, an engine which without such appurtenances produces, under very wide variations of pressure, load, and other distcauses, an oscillating movement of constant period, and have shown and described the same in an application filed on Aug. 19th, 1893, Serial No. 483,563. A description of the principle of the construction and mode of operation of this device is necessary to an understanding of my present invention. When a spring which possesses a sensible inertia is brought under tersion as by being stretched and then freed, it will perform vibrations which are isochronous and, as to period, mainly dependent upon the rigidity.