Search our collection

Clear all filters
Image
Category
Maker
Object type
Place
Date
Brass quadrant by Peter and John Dollond of 18-inch radius with optical sights on a tripod

Brass quadrant by Peter and John Dollond of 18-inch radius with optical sights on a tripod

1780-1820
Brass quadrant with stand, 1771

Brass quadrant with stand, 1771

1771
Components for Dollond portable quadrant

Components for Dollond portable quadrant

Twelve inch astronomical quadrant by Bird, employed in the observations of the transit of Venus in 1769, at Schiehallion 1774-76,

John Bird's Twelve inch astronomical quadrant

1760-1769
Quadrant on a stand made by B.C. Phelps, United States, 1861. Polished brass frame and index arm. Signed on the left strut: B.C. Phelps | 1861. Polished brass scale from 0° to 93° every 20'. Silver vernier to 1', zero at the left. There is no tangent screw; the clamping screw is on the back of the index arm. Two index shades (both red) on a swivelling arm. The index glass, without adjustment, is fixed at the pivot; there is no horizon glass. The sight vane has one pinhole, and is fixed at the bottom of the index arm, at the 0' of the vernier; a second sight vane with two cross-wires is fixed on the index arm just below the pivot. A detachable bubble level in a brass case is clamped on to the left strut (a later addition probably by a different maker). The quadrant is fitted on a column and can be rotated in the horizontal plane, and secured by a milled knob. The stand consists of a painted brass column on three painted brass feet levelled by milled screws.

Quadrant on pillar stand.

1861
Brass quadrant, 6-inch radius with stand and an optical sight by J. Sisson, London.

Brass quadrant

1749-1783