Brass quadrant by Peter and John Dollond, 18 inch radius with optical sights on tripod

Brass quadrant of 18-inch radius with optical sights on a tripod stand. Made by Peter and John Dollond, St Paul’s churchyard, London, and issued by the British Admiralty for surveying work in Lower Canada.

This London-made quadrant was supplied by the British Admiralty around 1800 for surveys in Lower Canada, present-day Quebec. It is associated with Lt.-Colonel Joseph Bouchette (1774-1841), the Surveyor-General of Lower Canada.

Quadrants are used to measure the altitude of celestial objects and the angular distance between them. They were used by surveyors to determine precisely their longitude and latitude.

Much of the territory in Lower Canada was relatively unknown to the British. They produced maps, charts and topographical sketches of the region as they sought to defend their interests against indigenous peoples, and against the French and Americans.