Dip circle with 11 inch needle, c 1820.

Made:
1820 in London England and London
maker:
Peter Dollond

Dip circle, 11 inch needle, by Dollond, c.1820

Dip circles are used to measure the angle between the direction of the earth's magnetic field and the horizontal at any point on the earth's surface. A freely-suspended magnetic needle lies horizontal only at the magnetic equator, where the attraction to the poles is equally balanced. Elsewhere, the needle dips to an angle depending on the distance from the nearest magnetic pole, and vertically at the poles. Scientists frequently took dip circles on field expeditions from the 18th century onwards. This example was made by Dollond of London.

Details

Category:
Terrestrial Magnetism
Object Number:
1876-805
type:
dip circles and dip needles
credit:
Admiralty Hydrographic Department

Parts

Dip circle with 11 inch needle, c 1820.

Dip circle with 11 inch needle, c 1820.

Dip circle, 11 inch needle, by Dollond, c.1820

Object Number:
1876-805 Pt1
type:
dip circles and dip needles
Dip circle needles in storage box

Dip circle needles in storage box

Part

Object Number:
1876-805 Pt2
type:
needles