Fuller's Computing Telegraph Circular Slide Rule

George Philip and Son · 1861-1865

This square yellow cardboard instrument has circular discs that rotate about a metal pin. The edges of the instrument are bound in red morocco leather. The disc on one side, Fuller's Time Telegraph, is designed to rapidly compute intervals between dates on the calendar. It has linear scales for the 365 days of the year around the edge of the disc and on the surrounding circle on the frame. In addition to the name of the instrument and directions for finding the number of days and weeks between two dates, there is a copyright mark: Entered according to Act of Congress in the year 1845 by John E. Fuller in the Clerk's Office of the District Court of the State of Massachusetts (/) Eng[rave]d by G. G. Smith, Boston.