Accession No
2817
Brief Description
dry marine compass, by Kelvin and Hughes Ltd., British, 1950 (c)
Origin
Great Britain
Maker
Kelvin and Hughes Ltd.
Class
navigation; magnetism
Earliest Date
1950
Latest Date
1950
Inscription Date
Material
paper (card); metal (alloy, brass); liquids; glass
Dimensions
breadth 305mm; diameter 282mm; height 195mm
Special Collection
Provenance
Purchased from Christie’s, South Kensington, London, England; lot 162, 07/01/1982.
Inscription
‘LORD
KELVIN’S
PATENT
NO.380
REGISTERED’
‘KELVIN & HUGHES LTD’
‘TEN INCH DRY
COMPASS CARD’
‘MADE IN GREAT BRITAIN
BY
KELVIN & HUGHES LTD’
‘SERIAL NO 55 [-] 211’
Description Notes
Dry card marine compass. Part gold painted metal alloy bowl, painted white inside with 4 lubber lines. Translucent bottom weighted with liquid. Glazed brass bezel. Printed paper card connected to cap by radial threads. Card divided to 128 points, with fleur-de-lys, and 0-360o.
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:44464
Images (Click to view full size):
