Add to albumA theodolite is a surveying instrument for measuring horizontal and vertical angles. This brass example was made around 1750, and retailed by London optician Benjamin Martin (1704/5-1782).
This instrument consists of a compass, with two spirit levels, and has both fixed and movable sighting vanes on a graduated circle. It could be used if attached to a ball-and-socket levelling head and tripod (neither shown here), to take readings in both vertical and horizontal planes.
Martin was a much respected designer of scientific instruments and had a shop at the sign of 'Hadley's Quadrant and Visual Glasses' in Fleet Street in London. He was also a prolific writer and gave lectures on Natural Philosophy illustrated with his instruments.
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- Online ID: 000-100-044-570-C
- Image Rights Holder: National Museums Scotland
- Project:
National Museums Scotland
Project description View all records in project
- Ref: National Museums Scotland T.1971.87
- Date: Around 1750
- Material: Circumferentor / compass
- Dimensions:
- What: Circumferentor / compass
- Subject: 5. CARTOGRAPHY, Surveying (Departmental Classification)
- Who: B. Martin, London (Maker)
- Where: England, London
- Event:
- Description: Circumferentor and compass by B. Martin of London
- References:
- For an explanation of the evolution of the theodolite, see Bennett, J.A. The Divided Circle: A history of instruments for astronomy, navigation and surveying. Oxford: 1987. pp 145-9
- Millburn, John R., Benjamin Martin author, instrument-maker, and country showman. Leyden: 1976, pp 224-5
- Millburn, John R., Retailer of the sciences: Benjamin Martin's scientific instrument catalogues, 1756-1782. London: 1986, p 24
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