Accession No
0234
Brief Description
pocket compass, c.1825
Origin
Maker
Class
magnetism
Earliest Date
1825
Latest Date
1825
Inscription Date
Material
wood (mahogany); paper; metal (brass, steel)
Dimensions
box length 55mm; breadth 57mm; thickness 21mm
Special Collection
Robert Whipple collection
Provenance
Purchased by Robert Stewart Whipple in Southampton on 28/08/1926.
Inscription
Description Notes
Paper rose with 32 points and fleur-de-lys for North, graduated 0 - 90˚ - 0 - 90˚ - 0. Steel needle and brass locking bar. Glass held in place by Brass rim. Set in hinged mahogany box.
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:43338
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