Accession No

4246

Brief Description

Wheatstone Bridge, Callendar and Griffiths type II, Collins' patent, by Cambridge Instrument Company Ltd., English, 1924

Origin

England; London

Maker

Cambridge Instrument Company Ltd.

Class

electrical

Earliest Date

1924

Latest Date

1924

Inscription Date

Material

wood; metal (brass, steel, mercury?), plastic (ebonite)

Dimensions

length 475mm; breadth 230mm; height 270mm

Special Collection

Cambridge Instrument Company Collection

Provenance

Donated by the Cambridge Instrument Company.

Inscription

“CAMBRIDGE INSTRUMENT CO LTD ENGLAND / No. L-12304 / CALLENDAR & GRIFFITHS BRIDGE / COLLINS’ PATENT” (on top)

Description Notes

Wheatstone Bridge, Callendar and Griffiths type II; made by Cambridge Instrument Company, c.1925;
Eight resistance coils; ‘Collins’ Patent’ mercury contact using eight brass plugs; four pairs of brass terminals marked ‘G’, ‘P’, ‘C’ and ‘B’ respectively; coils marked from 10 to 1280 (0.10 to 12.8 ohms; each coil differs by 0.10 ohm from the sum of those below it); double slide wire with 30-cm scale; vernier scale on sliding contact; stepped wooden case with ebonite tops. Steel stand probably not original;

Condition: good; complete; excess mercury removed from contacts; residual mercury

References

Events