Accession No

0557

Brief Description

surveyor’s compass, by Dudley Adams, English, 1798

Origin

England; London

Maker

Adams, Dudley

Class

magnetism

Earliest Date

1798

Latest Date

1798

Inscription Date

1798

Material

wood (mahogany); metal (steel, brass); glass; paper

Dimensions

box length 151mm; breadth 152mm; thickness 27mm

Special Collection

Robert Whipple collection

Provenance

Purchased from R. Beard, London, on 26/05/1929.

Inscription

‘D ADAMS LONDON’ (centre of compass rose)
‘Dec 29 1798’(ink inside lid)

Description Notes

32-point paper rose with sun face. Graduated 0 - 90˚ - 0 - 90˚ - 0, numbered by 10˚, divided to 1˚. Brass scale above graduated 0 - 360˚, numbered by 10˚, divided to 1˚. Steel needle with locking bar. Glass held in place by brass ring.
Fitted mahogany box with brass hinges.

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:43342