Joseph Knox (1805-1877) and Charles J. Shain (1822-1891) opened their own shop in 1850, and soon thereafter acquired the circular dividing engine that Jesse Ramsden had built in 1774. Although Knox & Shain remained in business until 1929, this instrument must have been made before 1880, when the Ramsden dividing engine was sold to Henry Morton, professor at the Stevens Institute of Technology. Morton, in turn, gave this historic engine to the Smithsonian Institution.
If this transit instrument resembles those made by William J. Young, it is because Knox had been Young's foreman and Shain had apprenticed with and then worked for Young. The
horizontal circle is inside the compass face, graduated to 30 minutes of arc, and read by vernier to single minutes. The face is dark, and the needle ring is silvered. There are level vials outside the compass, at south and east.