- Brief Description
- A large format rectangular protractor of the first half of the 18th century. It has been attributed to the notable London maker Thomas Heath on the basis of the other instruments which it accompanied when acquired.
- Item type
- Object
- Makers
- Thomas Heath
- Provenance
- Presented by Howard Dawes.
- Object type
- Protractor
- Dimensions
- Height: 2mm Width: 405mm Depth: 102mm
- Inventory No
- 118805.1.7
Description
Brass rectangle whose upper face has bevelled edges, with a protracting scale [0] - 180 divided to 5, 1 and ½° and numbered by 10, running in both directions. On the raised portion are two 10" diagonal scales, one dividing an inch and a half inch into 100 equal parts, and the other similarly dividing ¼ and ¾".
The reverse carries scales of equal parts 15, 20, 25, 30, 35, 40, 45, 50 combined with three scales of chords C [0] - 90 to different radii. Separated by a band of leaf decoration are plain scales labelled on the left side: Hou (hours), Lat (latitude), Lea (leagues), Rum (rhumbs), Cho (chords), Sin (sines), Tan (tangents), S.T. (sine and tangent). Along the length of these are additional scales for L (latitude or longitude?), E.P. (equal parts) and Sec (secants). There are also additional chord scales to alternative radii and a scale Mo (meridional parts?).
Related Items
More related items- Rectangular Protractor and Plain Scale, London, c.֫. 1730Inventory Number 18805.1.6
- Architectural Protractor to the Design of William Halfpenny, by Thomas Heath, London, c. 1728Inventory Number 18805.1.5
- Architectural Protractor to the Design of William Halfpenny, by Thomas Heath, London, c. 1728Inventory Number 18805.1.4
Sector, by Thomas Heath, London, c. 1730Inventory Number 36704