Accession No

1123

Brief Description

geomantic compass, by Xi Yang-San, late 18th C

Origin

China

Maker

Xi Yang-San

Class

magnetism

Earliest Date

1775

Latest Date

1800

Inscription Date

Material

wood (boxwood); metal (steel); organic (mother of pearl)

Dimensions

box diameter 345mm; thickness 43mm

Special Collection

Provenance

Gift from John Couch Adams, 03/1976.

Inscription

Description Notes

Boxwood compass; 24 concentric rings of characters (see history file for details); inset central compass with needle but glass missing; characters inscribed in red and black. Instructions on the reverse with signature and place of origin (Xing An Wang Yang). Circular black box; lid decorated with inlaid mother-of-pearl scene of figures in a landscape with trees. Inside the lid of the box is a longhand description of the compass rings.

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:43581