Oliver Evans, an American inventor, born in Newport, Del., in 1755, died in New York, April 21, 1819. He was apprenticed to a wheelwright, and before he had reached the age of manhood the construction of a land carriage to be propelled without animal power began to occupy his attention. At the age of 22 he invented a machine for making card teeth which superseded the old method of manufacturing them by hand. Two years later he entered into business with his brothers, who were millers, and in a short time invented the elevator, the conveyor, the drill, the hopper-boy, and the descender, the application of which to mills worked by water power effected a revolution in the manufacture of flour. In 1786-"7 he obtained from the legislatures of Maryland and Pennsylvania the exclusive right to use his improvements in flour mills, and Maryland also gave him a similar privilege with respect to steam carriages. It was not till 1799 or 1800 that he was able to set about the construction of a steam carriage; but finding that his steam engine differed in form as well as in principle from those in use, it occurred to him that it could be patented and applied to mills more profitably than to carriages; and in this he was completely successful.

This was the first steam engine constructed on the high-pressure principle; and to Evans, who had conceived the idea of it in early life, and in 1787 and again in 1794-'5 had sent to England drawings and specifications, the merit of the invention belongs, although it has been common to assign it to Vivian and Trevithick, who had had access to Evans's plans. In 1803-'4, by order of the board of health of Philadelphia, he constructed the first steam dredging machine used in America, consisting of a flat scow with a small engine to work the machinery for raising the mud. The machine, which he named the "Orukter Amphibolos," propelled itself on wheels to the Schuylkill, a distance of 1 1/2 m., was fitted with a paddle wheel in the stern, and navigated the river to its junction with the Delaware. This is believed to have been the first instance in America of the application of steam power to the propelling of land carriages. He predicted the time when such carriages would be propelled on railways of wood or iron, and urged the construction of a railroad between Philadelphia and New York, but was always prevented by his limited means from prosecuting his mechanical experiments to the extent he desired.

He was the author of " The Young Engineer's Guide " (8vo, Philadelphia, 1805; translated into French, Paris, 1821-'5 and 1838), and " Miller and Millwright's Guide" (8vo, Philadelphia, 1797, 1807, 1818; and 8vo, Paris, 1830; 14th ed., with additions and corrections by Thomas P. Jones, and a description of an improved merchant flour mill by C. and O. Evans, 8vo, Philadelphia, 1853).