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Portable altazimuth telescope
This was one of 5 altazimuth instruments commissioned from Troughton and Simms for the British Transit of Venus expeditions of 1874.
An altazimuth instrument is a telescope with scales and mounting that allow both local coordinates - the altitude and the azimuth - of a star to be measured without the need of any additional apparatus.
The telescope and mount each have their own fitted wooden box. The telescope is made of brass and has a focal length of 550 mm, a lens aperture of 50 mm , and an overall tube length of 250 mm. The diameter of the setting circles is 400 mm. In addition to the telescope and mount there are 2 eyepieces, 4 fine reading microscopes, 2 course reading microscopes, 2 300 mm diameter glass plates (1 broken), 2 enlarging lenses to read the altazimuth scale (1 missing) and 2 spirit levels.
An altazimuth instrument is a telescope with scales and mounting that allow both local coordinates - the altitude and the azimuth - of a star to be measured without the need of any additional apparatus.
The telescope and mount each have their own fitted wooden box. The telescope is made of brass and has a focal length of 550 mm, a lens aperture of 50 mm , and an overall tube length of 250 mm. The diameter of the setting circles is 400 mm. In addition to the telescope and mount there are 2 eyepieces, 4 fine reading microscopes, 2 course reading microscopes, 2 300 mm diameter glass plates (1 broken), 2 enlarging lenses to read the altazimuth scale (1 missing) and 2 spirit levels.
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Object Details
| ID: | AST0962 |
|---|---|
| Collection: | Astronomical and navigational instruments |
| Type: | Telescope |
| Display location: | Not on display |
| Creator: | Troughton & Simms |
| Places: | Baie de l'Oiseau; Venus |
| Events: | Transit of Venus, 1874 |
| Date made: | 1870 |
| Credit: | National Maritime Museum, Greenwich, London |
| Measurements: | Overall: 533 x 254 mm |
| Parts: |
Portable altazimuth telescope
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