One of a collection of surveying, nautical, astronomical, meteorological and drawing instruments - a brass sector, marked R.191, with various scales engraved on both sides, in a fitted wooden box, made by Thomas Jones of Charing Cross, London, a later trade label has been pasted into the box by the instrument maker W.F Stanley, handwritten on label is 'adjusted H 7/11/84', made in late 18th - mid 19th century

English sector, used in navigation, maker unknown, probably from the nineteenth century

Six-inch brass sector by Michael Butterfield, Paris, c. 1700

Six-inch ivory sector opening to 12-inches, used for trigonometric calculations, maker unknown

Six-inch boxwood sector opening to 12-inches, used for trigonometric calculation, maker unknown

Folding 6" sector extending to 12", made of ivory and brass, made by Hunter of Edinburgh, c. 1800

Brass Gunter's sector, English, unsigned, probably by Elias Allen, London, c. 1625

Portuguese sector of brass, 18th century