rolling sphere planimeter
Date: 1907
Inventory Number: 1997-1-0250
Classification: Planimeter
Dimensions:case: 9.5 × 33.5 × 24.1 cm (3 3/4 × 13 3/16 × 9 1/2 in.)
Accessories: carrying case
DescriptionRolling sphere planimeter in a rectangular, wooden box. Planimeter consists of a long metal tracer arm with a stylus on the end, attached to a black metal frame containing two silver wheels. The tracer arm is attached to the frame by a clamp and a spring. On top of the frame, between the two wheels, is a metal bar. There is a white plastic dial, displaying the numbers 1-45 in intervals of five, on top of the end of the bar closest to the tracer arm. A white plastic vernier scale is wrapped around the other end of the bar. The rounded edge of a hemispherical piece of metal is in contact with the side of the bar. There are several objects not attached to the planimeter: a graduated, adjustable metal bar [an extension to the tracer arm?], a shorter, flat metal bar, a metal bar with a square cross-section, a brass roller with hooks on either side, and a small brush.
The inside of the box is felt. There are three pieces of paper attached to the inside of the lid. The top one contains a four-column table with the printed headings "Scales/Position of the vernier on the tracer bar/Value of the unit of the vernier on the measuring roller/Constant." The values are filled into the table by hand, the "Constant" column left blank. At the bottom of the table, "Zurich, the 12 Februar. 1907. No. 2232. G Coradi," is written, the date and the no. written in by hand.
Below the table are instructions typed in German. To the left of the German instructions is a typed translation that reads as follows: "(translation of instructions) / to take the instrument from the case, hold it with the right hand on the large frame, never by the frame of the measuring roller, and with the left hand hold the tracer arm. Lift carefully from the case without the use of force with the left hand." In handwriting it is written, at the top of the card: "To read sq. inches, set vernier on 3258."