Thomson's mirror marine galvanometer, 1858

Made:
1858 in Glasgow
maker:
James White
and
White & Barr
(Lord Kelvin) Thomson's marine mirror galvanometer (Lord Kelvin) Thomson's marine mirror galvanometer (Lord Kelvin) Thomson's marine mirror galvanometer (Lord Kelvin) Thomson's marine mirror galvanometer

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Creative Commons LicenseThis image is released under a Licence

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(Lord Kelvin) Thomson's marine mirror galvanometer
Science Museum Group Collection
© The Board of Trustees of the Science Museum

(Lord Kelvin) Thomson's marine mirror galvanometer
Science Museum Group Collection
© The Board of Trustees of the Science Museum

(Lord Kelvin) Thomson's marine mirror galvanometer
Science Museum Group Collection
© The Board of Trustees of the Science Museum

(Lord Kelvin) Thomson's marine mirror galvanometer
Science Museum Group Collection
© The Board of Trustees of the Science Museum

(Lord Kelvin) Thomson's marine mirror galvanometer, made by White & Barr, Glasgow, Scotland, 1858.

A mirror galvanometer is a particularly sensitive electrical indicating instrument and was used to detect the extremely weak currents received through long submarine cables. Instead of a needle indicator, a mirror with a bar magnet cemented on the back is suspended on silk threads within the coil. A beam of light shone on the mirror is reflected on to a scale card some distance away, thus magnifying any movement of the mirror. Although he did not originate it, William Thomson, later Lord Kelvin (1824-1907) made improvements which he patented in 1858.

Details

Category:
Electricity and Magnetism
Object Number:
1876-41
Materials:
mahogany (wood), brass (copper, zinc alloy), leather and copper (metal)
Measurements:
overall: 260 mm x 145 mm x 143 mm, , 1.945kg
type:
galvanometer
credit:
From Sir William Thomson (Lord Kelvin)