This instrument belonged to the John C. Green Astronomical Observatory at Princeton University. New, it cost $680. It made after 1877 when the Observatory was equipped, and before 1898 when Buff and Berger went their separate ways. The horizontal circle is silvered,
graduated to 20 minutes, and read by opposite verniers with magnifiers and ground glass plates to 20 seconds. The vertical circle is silvered, graduated to 20 minutes, and read by opposite
verniers with magnifiers and ground glass plates to single minutes. The telescope has a filar
micrometer eyepiece; the attached level has a micrometer adjustment.Ref: Buff & Berger, Hand-Book and Illustrated Catalogue of the Engineers' and Surveyors'
Instruments (Boston, 1890), p. 129.
