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brass moving wire micrometer, 1740-1760
Brass moving wire filar micrometer by J. Sissons, London, 1740-1760
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This type of micrometer was considered the best of its time. It was attached to the front of a telescope and used to measure the angular separation of stars, or the angular separation between two positions of the same star. One of the vertical wires, or sights, is fixed while the other is moveable. The exact distance between the two being shown on the dial.
- Measurements:
-
overall: 85 mm x 225 mm x 140 mm, 0.7 kg
- Materials:
- brass (copper, zinc alloy) , iron and steel (metal)
- Object Number:
- 1927-1491 Pt1
- type:
- instrument component and filar micrometer
- Image ©
- The Board of Trustees of the Science Museum
