rolling sphere planimeter
Date: 1903
Inventory Number: 1997-1-0247
Classification: Planimeter
Dimensions:case: 9.7 × 33.3 × 23.6 cm (3 13/16 × 13 1/8 × 9 5/16 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 with 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 metal 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 brass roller with hooks on either side, and a graduated metal bar in the shape of an oval with pointed ends.
The inside of the box is felt. There are two 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 ["Costant" is crossed out]." The values are filled into the table by hand, the fourth column empty. At the bottom of the table, "Zurich, the 10 December 03. No. 1777. G Coradi," is written, the date and the no. written in by hand. Below is the hand written note: "For scale of 1 in^2 per large unit. Set arm at 3276. Jan. 5, '24." The bottom of the note contains initials, the second letter probably being a "J".