James Rumsey, an American inventor, born at Bohemia Manor, Cecil co., Md., about 1743, died in London, England, Dec. 23, 1792. In September, 1784, he exhibited on the Potomac, in the presence of Gen. Washington, a boat which worked against the stream by means of mechanism. He subsequently gave his attention to steam as a motive power, and in March, 1786, propelled a boat on the Potomac by a steam engine, which secured motion by the force of a stream of water thrown out by a pump at the stern. In December, 1787, the experiment was successfully repeated on a larger scale. About the same time he became involved in a controversy with John Fitch. (See Fitch, John.) In 1788 the "Rumsey society " was formed in Philadelphia; and the inventor going to England, a similar society was formed in London, a boat and machinery were built for him, and he obtained patents for his inventions in Great Britain, France, and Holland. A successful trip was made upon the Thames in December, 1792, and he was preparing for another experiment when he died.

He published a "Short Treatise on the Application of Steam" (1788).