"Made by Benjn Rittenhouse"
telescope 26 inches long
This is one of the earliest wye levels in America. It was made by Benjamin Rittenhouse around 1785, and owned by George Gilpin, who was the chief surveyor for the Potowmack Canal
Navigation Company. Although this Canal Company had been organized in 1772, the project
was shelved during the Revolution. It was resumed in 1785, and construction began the
following year. Thomas Ellicott purchased the level at the sale of Gilpin's estate in Alexandria,
Virginia, in 1813, and it remained in his family until its donation to the Smithsonian in 1997.
The level vial of this instrument is mounted above the telescope; in the form that would become
standard in the 19th century, the level hangs below the telescope.
Ref: Silvio A. Bedini, "The Telescopic Level in Early America," Rittenhouse 11 (1997):