Thomson's Mirror Marine Galvanometer, 1858

Made:
1858 in Glasgow
maker:
White & Barr

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Science Museum Group Collection
© The Board of Trustees of the Science Museum

Science Museum Group Collection
© The Board of Trustees of the Science Museum

Science Museum Group Collection
© The Board of Trustees of the Science Museum

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:
brass (copper, zinc alloy), copper (metal), leather and mahogany (wood)
type:
galvanometer
taxonomy:
  • furnishing and equipment
  • measuring device - instrument
credit:
From Sir William Thomson (Lord Kelvin)