Thomas Whitney (d. 1823) served an apprenticeship with a mathematical
instrument maker in London before moving to the United States. He set up shop in
Philadelphia and, according to an announcement in the Federal Gazette for
April 12, 1798, prepared to make "various instruments in the most approved
and accurate manner." Over the course of the next quarter century, Whitney
made about 500 surveyor’s compasses, and a few other instruments as well. He
also trained William J. Young, who would become the most important mathematical
instrument maker in the United States in the middle decades of the 19th century.