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Mural quadrant
Bradley's quadrant follows the same design as Halley's, the main difference being the metal used. After twenty years of use, the frame of Halley's iron quadrant had buckled under its own weight and become inaccurate. Bradley made his quadrant from brass, a lighter material, in order to overcome this problem. Bradley's quadrant also has an arc which has been hand-divided and signed by one of the great instrument makers of the day, John Bird.
See, John Bird, The Method of Constructing Mural Quadrants, ...Published by Order of the Commissioners of Longitude, 1768.
Carole Stott, 'The Greenwich Meridional Instruments (up to and including the Airy Transit Circle)', Vistas in Astronomy, 28, (1985), pp. 133-145
See, John Bird, The Method of Constructing Mural Quadrants, ...Published by Order of the Commissioners of Longitude, 1768.
Carole Stott, 'The Greenwich Meridional Instruments (up to and including the Airy Transit Circle)', Vistas in Astronomy, 28, (1985), pp. 133-145
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Object Details
| ID: | AST0971 |
|---|---|
| Collection: | Astronomical and navigational instruments |
| Type: | Telescope |
| Display location: | Display - ROG |
| Creator: | Bird, John |
| Date made: | 1750 |
| Credit: | National Maritime Museum, Greenwich, London |
| Measurements: | Overall: 2438 mm |
| Parts: | Mural quadrant |