Accession No
1338
Brief Description
thermal, reflecting galvanometer, Duddell-type, by Cambridge Scientific Instrument Company Ltd., English, 1916
Origin
England; Cambridge
Maker
Cambridge Scientific Instrument Company Ltd.
Class
electrical
Earliest Date
1916
Latest Date
1916
Inscription Date
Material
metal (brass); wood; glass
Dimensions
height 355mm; base diameter 295mm
Special Collection
Provenance
Transferred from the Cavendish Laboratory, University of Cambridge. Purchased in 1916 by the Cavendish Laboratory.
Inscription
‘No. 31089
DUDDELL’S PATENT
U.K. 17642. 1900’ (on brass block)
‘E. 929’ (on wood base (added))
Description Notes
Circular brass and wooden base; two bubble levels; two threaded brass terminals; mechanism, including permanent magnet, heating element, and suspension mounted on three black columns; front and back circular glazed windows showing mirror; brass block removable to show suspended loop and heating mechanism; black-painted wooden rectangular cover, with removable lid and with glazed window.
Condition: fine (suspension intact); complete.
Anthony Constable visited (13.12.2010) to research the galvanometer and mentioned that the mirror has slipped down and the junction of wires where it links to the heating mechanism is apart at the bottom where it ought to be together.
References
Events
Description
An instrument for the sensitive measurement of small alternating currents. The current heats a resistance wire, which then deflects a mirror through its effect on a thermocouple. A light beam reflected onto a standard scale is used to measure the size of deflection, which can then be converted to a measurement of current in amps.
17/02/2015
Created by: Joshua Nall on 17/02/2015
FM:41058
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