James Rumsey (1743 – December 21, 1792) was an American mechanical engineer chiefly known for exhibiting a boat propelled by machinery in 1787 on the Potomac River at Shepherdstown in present-day West Virginia before a crowd of local notables, including Horatio Gates.

[1] His cousin was Benjamin Rumsey, a notable Maryland jurist and statesman, who also grew up at Bohemia Manor.

Armed with the certificate, Rumsey obtained a patent from the Virginia legislature for "the use of mechanical boats of his model" and also gained an investor James Mcmechen.

In July 1785, he was recommended by Washington and appointed the superintendent of the newly formed Patowmack Company[2] to oversee the clearing of rocks at what is now Harper's Ferry.

For a year, Rumsey oversaw work on the Potomac River site, while his assistant and brother-in-law Joseph Barnes did much of the building of the boat around Shepherdstown.

The work required much manual labor and difficult blasting, and Rumsey found himself directing a large and restive gang of about a hundred workmen, including leased slaves and bondsmen, encamped in a remote area, without adequate supplies.

Valve castings, cylinders, and other pieces which had been made in Baltimore and Frederick were installed that December, and the boat was taken downriver to Shenandoah Falls for a test.

The single-cylinder pump would draw several gallons of water from beneath the boat and send it down a copper pipe to the stern.

This was resolved by replacing the copper pipe with a square wooden trunk with flapper valves in the bottom to allow water in from the river, to relieve the negative pressure at the pump.

Rumsey was very protective of his designs and, though he was even more plagued by money problems, he sent the boat machinery to Philadelphia in March 1788.

Some Philadelphia businessmen attempted to make the men set up a joint effort; but after years of travails and poverty, Fitch was not in a mood to compromise.

While some of these relate to steamboats (like his water-tube boiler design, which made the steam engine much smaller and more efficient) most are concerned with hydrostatics and water power.

On December 20, 1792, on the eve of the demonstration of his new steamboat the Columbia Maid, he had just finished delivering a lecture to the Society of Mechanic Arts, when he was suddenly stricken with a severe pain in his head, and died the next morning.

Another Rumseian Society[8] was formed in Shepherdstown in the 1980s to construct a replica of the successful Rumsey steamboat and celebrate the boat's bicentennial in 1987.