The Museum has the original bill of sale, which indicates that John Ferris, a surveyor of
Dutchess County, New York, bought this transit from Stackpole & Brother in 1866. The basic
instrument cost $250, while the meridian finder--marked "Stackpole's Mern. Findr. Patented,
Sep. 26, 1865 107"--cost an additional $40. William Stackpole's patent (#50,182) describes a
small reflector that attaches to the objective end of the telescope, and that enables a surveyor to
easily use the sun to locate the true meridian.
Ref: Conrad S. Ham, "A Family History of a Group of Surveying Instruments, 1750 to the
Present Year 1954," Annual Report of Proceedings of the Connecticut Society of Civil Engineers, 70 (1954): 134-138.