Accession No

4245

Brief Description

Wheatstone Bridge, Callendar and Griffiths type II, by Cambridge Scientific Instrument Company Ltd., English, c.1902

Origin

England; Cambridge

Maker

Cambridge Scientific Instrument Company Ltd.

Class

electrical

Earliest Date

1902

Latest Date

1902

Inscription Date

Material

Wood; metal (brass, mercury?); plastic (ebonite)

Dimensions

length 450mm; breadth 196mm; height 129mm

Special Collection

Cambridge Instrument Company Collection

Provenance

Donated by the Cambridge Instrument Company.

Inscription

“CAMBRIDGE SCIENTIFIC INSTRUMENT CO. LTD. / CAMBRIDGE No. 1818 / CALLENDAR & GRIFFITHS PATENT” (on brass bar screwed to ebonite top);
“T.R. 65 (?)” (on wooden top);

Description Notes

Wheatstone Bridge, Callendar and Griffiths type II; made by Camb. Sci. Inst. Co., c.1902;
Seven resistance coils; ‘Collins’ Patent’ mercury contacts using seven brass and ebonite plugs; coils marked from 10 to 640 (0.1 to 6.4 ohms; each coil differs by 0.1 ohm from the sum of those below it); eight brass terminals, six marked ‘G2’, ‘P1’, ‘P2’, C1’, ‘C2’, and ‘B’, respectively; double slide wire with 28-cm brass scale; vernier scale on sliding contact; wooden case with ebonite top; upper wooden box fixed on top;

Condition: fair (one slide wire broken); incomplete (two plugs missing); no liquid mercury in contacts

References

Events