Accession No
3181
Brief Description
marine compass, in Kelvin-type binnacle, by Kelvin and Hughes Ltd., Lilley and Reynolds Ltd., 1950 (c)
Origin
England; London
Maker
Kelvin and Hughes Ltd. Lilley and Reynolds Ltd.
Class
navigation; magnetism
Earliest Date
1950
Latest Date
1950
Inscription Date
Material
metal (brass, wire, iron); glass; wood; paper (card)
Dimensions
compass diameter 258mm; height overall 1470mm
Special Collection
Provenance
Purchased at Sotheby’s; lot. 519, 6/6/1984. Purchased with the assistance of a grant-in-aid from the Preservation Fund, administered by the Science Museum.
Inscription
‘KELVIN & HUGHES LTD.
MADE IN GREAT BRITAIN TYPE 72956
SERIAL No.5110’ (maker’s plates)
‘KELVIN & HUGHES LTD
MADE IN GREAT BRITAIN’ (on inclinometer)
‘LILLEY & REYNOLDS. LTD
LONDON E.C.3.’ (on compass card)
Description Notes
Dry-card compass in Kelvin-type binnacle. Brass removable cover with side and top glazed apertures, and removable oil-lamp with handle housed at side. Dry-card compass with cut-away card and housing for 2 magnets. Printed black on white card with compass rose and degree scale 0-360o to 1o; 2 wire lubber ‘lines’. Brass gimbal mount to brass fitting above slatted-wood binnacle, 2 compensating soft-iron spheres (painted red and green), carried by brass brackets, can be clamped at adjustable distance from the compass, each with scale of 10-12 1/4 ins. from the centre, divided to 1/4 inch. Hinged door and two removable panels (with locks) give access to permanent magnets (not extant); 2 brass brackets (one broken) behind carry cylindrical brass housing for permanent magnet (not extant). Bubble inclinometer with degree scale 45o-0-45o to 5o. Two makers plates. Square wooden base.
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:41367
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