Accession No

2211

Brief Description

marching compass, French, 1915 (c)

Origin

France

Maker

Class

magnetism

Earliest Date

1915

Latest Date

1915

Inscription Date

Material

metal (aluminium, brass and one other); glass

Dimensions

length 91mm; breadth 55mm; thickness 21mm

Special Collection

Provenance

Transferred from Department of Geography, University of Cambridge, Cambridge, England, 05/1969.

Inscription

‘MK 104270’ (lid)

Description Notes

Metal alloy; black finish. Hinged lid with sighting vane. Compass face graduated 0 - 64, numbered by 4, divided to 1. Fluourescent spots mark North, South, East and West and magnetised end of aluminium diamond-shaped needle. Scale graduated 0 - 60mm by 10. Hinges away under compass box. Brass shackle.

Condition

References

Events

Description
Magnetic compass
The magnetic compass consists of a magnetic needle attached to a compass card, graduated into angular points, and is used for navigation. The first known dry pivoted compass is dated as early as 1269.

The compass indicates the direction of the magnetic pole but there are problems caused by the difference between magnetic and true north (true north being the useful reading). The variation between the two must be calculated in order to obtain an accurate reading. True north was sometimes simply offset from the direction of magnetic north, but this did not allow for geographical variation. For this, charts were needed. The iron used in building ships during 19th century also led to problems because the magnetism of iron affected the compasses on board.
18/10/2002
Created by: Saffron Clackson on 18/10/2002

FM:44537