The Great Theodolite

The Great Theodolite

© Royal Geographical Society

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The Great Theodolite





Plate from book



This contraption is called a theodolite. This one was used by both William Lambton and George Everest when surveying in India.

It weighed 1100lbs (499kgs) and required 12 strong men to carry it. A theodolite is basically a very superior telescope, mounted on a sturdy structure. This structure was essential if the theodolite was to stand rock steady and give the highest precision of readings. It was also engineered so that the telescope could pivot both vertically and horizontally to enable readings to be taken.

This photo is taken from Historical Records of the Survey of India, vol. IV; 1830 to 1843; George Everest (1958).