Accession No
1036
Brief Description
compass, by Dollond, English, 1800 (c)
Origin
England; London
Maker
Dollond
Class
magnetism
Earliest Date
1800
Latest Date
1800
Inscription Date
Material
metal (brass, steel, silver); glass
Dimensions
diameter 86mm; thickness 16mm
Special Collection
Provenance
On loan from Gonville & Caius College, University of Cambridge from 1950.
Inscription
‘Dollond LONDON’ (rose)
Description Notes
Brass box and lid. Silvered 8-point rose. Lower scale divided 0 - 90˚ - 0 - 90˚ - 0.. Upper scale divided anticlockwise 0 - 360˚. Blued steel needle held in place by locking bar. Glazed.
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:43374
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