Carl Philipp Heinrich Pistor (1778-1845) was an employee of the Prussian
Postal Service who, having learned about optics and precision mechanics, opened an instrument workshop in Berlin in 1813, and who went into partnership with his son-in-law, Carl Otto Albrecht Martins (1816-1871) in 1841. Pistor & Martins remained in business until the early 1870s, specializing in large instruments for positional astronomy. Pistor & Martins instruments in the United States include the meridian circle at the University of Michigan (1854) and the meridian circle at the U.S. Naval Observatory (1865). American also bought several prismatic sextants based on Martins’ Prussian patent of 1843–a patent describing sextants and reflecting circles with a rectangular prism in place of the horizon glass found on ordinary instruments.
These bits and pieces are is all that remain of the prismatic sextant that was ordered in 1871 by Edward S. Holden, a recent graduate of the U.S.
Military Academy who was then teaching math to cadets at West Point. In 1873, when the prismatic sextant arrived from Germany, Holden was working as an astronomer at the U.S. Naval Observatory. In 1877 Holden sold it to Charles A. Young for the new John C. Green Astronomical Observatory at Princeton University, noting that it had cost him $198.50. The frame is brass. The silvered scale is graduated every 10 minutes from -10o (actually numbered 350) to +255o and read by vernier with tangent screw and magnifier.
Ref: Elias Loomis, Practical Astronomy (New York, 1855), pp. 101-102.
Charles A. Young papers, Princeton University Archives.