This is a metallic brass instrument with a cylindrical form. At its base, three adjustable feet support a circular base. Around the perimeter of this base are two banks containing four electrical leads each. The base also supports a cylindrical cover. with a rectangular window section at its centre through which part of the instrument’s interior can be viewed. At the top of the cover is a smaller cylindrical cover and two thin stems with knurled knobs at their tips.
This upper cover may be removed using three screws. Its removal reveals a cylindrical enclosure of glass and brass, as well as two screws that permit the hanging of a galvanometer suspension. This suspension is not in place.
The lower and larger of the covers may be removed using three screws. Its removal reveals a complex galvanometer mechanism consisting of two sets of coils, arranged vertically, with a window at the centre. Various screws and knurled nuts permit adjustment of components and access to the coils.
A folded piece of lined paper has been inserted through the centre of the instrument between the coils. Cradled within this paper is the suspension that would hang through the centre of the instrument when in use.
Accession Number: 2009.ph.228
Alternative Name:
Primary Materials: Copper Alloy: Brass, Iron, Glass
On the front of the cylinder affixed to the base, above the window:
“PASCHEN GALVANOMETER
THE CAMBRIDGE SCIENTIFIC INSTRUMENT CO. LTD.
CAMBRIDGE. ENGLAND
NO. 14480.”
Scratched into the metal just below the above marking:
“545”
Dimensions (cm): Maximum Diameter = 23; height = 31.2
Used to detect and measure electric current.
This instrument is in cosmetically good condition and appears to be complete. The surface has various small oxidized patches. The white lettering identifying the electrical leads is deteriorating. The suspension is not in pace. Insulation on the wiring under the circular base of the instrument is crumbling away. A section of wire has been soldered to the perimeter of the base, presumably to ground the instrument
Associated Instruments:
Manufacturer: Cambridge Scientific Instruments Ltd.
Date of Manufacture: c. 1910 to 1920.
Department of Physics, University of Toronto
This instrument appears in a Cambridge Scientific Instruments Co. trade catalogue published in 1912 and preserved on the Smithsonian website:
C.S.I. Co. Ltd. “Some Electrical Instruments – List No. 202” (1912) http://www.sil.si.edu/DigitalCollections/trade-literature/scientific-instruments/files/51687/ (accessed March 13, 2017)
An Paschen galvanometer identical to this one was used by R.C. Dearle in his thesis research at the Department of Physics and appears in photographs showing the experimental setup used. Raymond C Dearle, “Lines in the Infra-red Spectrum of the Mercury Arc” (MA Thesis, University of Toronto, March 1916) Western University Archives A07-032-001: Fig. 4, Arrangement of Apparatus.
Note that The Cambridge Scientific Instrument Co. Ltd became the Cambridge and Paul Instrument Co Ltd in 1920. In 1924, the name was shortened to the Cambridge Instrument Co.