Accession No
2351
Brief Description
geomantic compass, by Jiang Da-hong, Chinese
Origin
China
Maker
Jiang Da-hong
Class
magnetism
Earliest Date
Latest Date
Inscription Date
Material
wood (boxwood); glass; metal (steel)
Dimensions
diameter 95mm; thickness 18mm
Special Collection
Provenance
Bequeathed by R.S. Newall, 1978.
Inscription
Description Notes
Circular boxwood disc with inscription on base (Jiang Da-hong Xing An Xiu Yi); rounded edges; 5 concentric rings of information; inset compass with NS line; steel needle with red pointer; characters in red and black.
Complete.
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:43577
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