Variation Compass and magnetometer, 1837-1843

Unifilar variation compass and magnetometer by Henry Barrow &

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Unifilar variation compass and magnetometer by Henry Barrow &
Science Museum Group
© The Board of Trustees of the Science Museum

Unifilar variation compass and magnetometer by Henry Barrow & Company, 26 Oxenden Street, London. Used by Sir J. Richardson and on the voyages of Sir John Franklin.

The balance point of a magnetic needle was of crucial importance when measuring the difference between geographic north (around which the earth spins) and magnetic north. This example, made of brass tipped with platinum, comes from a magnetometer made by Henry Barrow of London, in about 1840. The instrument was used by Sir John Richardson and William Pullen on the Arctic Expeditions searching for Sir John Franklin.

Details

Category:
Terrestrial Magnetism
Object Number:
1876-790
Materials:
brass (copper, zinc alloy), glass, iron, silver plated and mahogany (wood)
Measurements:
overall: 400 mm x 230 mm x 220 mm, 3.695kg
type:
magnetometer, magnetic measuring instrument and magnetic variation compass
credit:
Meteorological Office