Accession No
0267
Brief Description
surveyor’s compass, by Thomas Wright, England, c. 1730
Origin
London; England
Maker
Wright. Thomas
Class
magnetism
Earliest Date
1730
Latest Date
1730
Inscription Date
Material
metal (brass, steel); wood; paper; glass
Dimensions
length 153mm; breadth 157mm; height 27mm
Special Collection
Robert Whipple collection
Provenance
Purchased by Robert Stewart Whipple from T. H. Court on 29/05/1926.
Inscription
‘Made by Thos. Wright. Instrument Maker to ye King.’ (centre of rose)
Description Notes
32-point paper rose, divided 0 - 360˚, 0 - 90˚ - 0 - 90˚ - 0 and 0 - 32. Fleur-de-lys for North. Steel needle. Brass scale above graduated 0 - 360˚. Brass rim holding glass. Birch (?) box. Decorative pattern engraved on inside and outside of lid. Lid with brass hinges decorated with engraved motifs. Box badly cracked across base, causing rose to tear.
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:43343
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