A black metal cylindrical magnet stands on a tripod of legs, two of which have brass leveling/attachment screws with ridged edges. A black metal strip is attached across the top of the magnet. Two small brass rods (terminals?) point directly upwards out of the strip. Between them is a small label affixed to the strip with a metal bracket frame. Around the exterior of the cylindrical magnet is painted “IIE”.
At the front the cylinder there is a box approximately 7×4.5cm in diameter with a round flat glass window in the centre and a brass tube projecting out from the top. At the top of the tube there is a ridged section and a protruding vertical rod. Below the window there is a small brass knob with a rod handle attached. This is labelled “clamp”, with an arrow indicating direction of rotation. Visible inside the window there is a small coil, which is dangling freely at an angle.
Accession Number: 2009.ph.187
Metal: Copper Alloy, Metal: Iron Alloy, Glass, Paper
Around the glass window there are labels “CAMBRIDGE INSTRUMENT CO. LTD. ENGLAND”, ” Nl-“, “CLAMP”, “21210”, and lastly with a scratched label “850”. The label affixed to the top of the plate reads “R=434Ω“
Height = 19, Width = 15.5, Length = 16.5
Mirror galvanometers precisely measure electrical current through the user measuring the deflection off a light source reflected off a small mirror suspended between the ends of a permanent magnet.
Very Good: The instrument appears to have all its parts, although the interior components may be damaged. The exterior iron surfaces of the instrument have been painted. The paint is in good condition, although it is chipped and worn around the rim of the cylinder. Here, the metal is rust. They brass is dirty and scratched, but has been enameled and this is intact. The “IIE” written on the exterior of the cylinder was painted on by hand. The ink on the label is slightly faded to brown, but very readable.
Manufacturer: Cambridge Instrument Co. Ltd. England
Date of Manufacture: 1900-1919
Provenance: Dr. Martin Lee’s Collection
Additional Information and References: