The telescope of this instrument has stadia wires and a hanging level. The base has a level vial, a screw adjustment, and a vertical arc that extends 50 degrees either way and that is read by vernier to singe minutes. There is also a plumbing arm for use on plane tables. Albert Joseph Seligman (1859-1935)
probably bought this alidade in the late 1870s, when he studied mining engineering at Freiberg, and he probably donated it to the Rensselaer Polytechnic Institute, his alma mater, around 1899, when he obtained a seat on the New York Stock Exchange. A German silver tag on the wooden box reads "Albert J. Seligman New York."