Images(6)

proportional compass

Date1751-1791

Inventory NumberDW0716

ClassificationProportional compass

Subject

Maker John Gilbert (II) fl. 1751-1791

Maker William Gilbert (I) fl. 1776 - 1813

Cultural Region

Place of Origin

Dimensions25.1 x 2.6 x 3.5 cm (9 7/8 x 1 x 1 3/8 in.)

Material

DescriptionThis proportional compass with a stabilizing arm is made of silvered brass. Its points are steel. The cursor is fixed in place by a large knurled thumb screw. On the back side of the cursor is a threaded collar. A smaller, knurled thumb screw is stored in the back collar and holds the stabilizing arm there when it is not being used. This small screw can be repositioned to a threaded sleeve at the end of a compass arm when the stabilizing arm is in use.

The stabilizing arm is a long, narrow, slotted bar, which is attached to a long, fine-adjustment screw with a knurled head. This screw goes through a pivoting collar standing upright from the surface at the end of one of the proportional compass arms. The far end of the stabilizing arm is held against a threaded sleeve at the end of the other compass arm by means of the small knurled screw thumb screw (mentioned above). This will keep the proportional compass fixed to a set opening.

Sector scales are engraved on the arms of the proportional compass. They include a line of "Lines" (also known as a line of equal parts), a line of "Circles," line of "Solids," and line of "Planes."

Signedon one arm: Gilbert London

Curatorial RemarksXRF analysis of the metals was done by Katherine Eremin and Sara Schechner in August 2007.

ProvenanceDavid Wheatland purchased from Alain Brieux, Paris, May 1, 1963 (lot 11/2). Donated to CHSI 1985.