Oil lamp base for Thomson mirror speaking galvanometer, 1858

Made:
1858 in City of London
Thomson mirror speaking galvanometer, made by Elliott Brothers, Strand, London, England, 1858 (Pt1); Lamp cover for 1925-179 Pt 1 (right hand object):
      
      Thomson mirror speaking galvanometer, made by Elliott Brothers, Strand, London, Thomson mirror speaking galvanometer, made by Elliott Brothers, Strand, London, England, 1858 (Pt1); Lamp cover for 1925-179 Pt2: 
      
      Lamp cover for Thomson mirror speaking galvanometer, made by Elliott Brothers, Strand, London, 1925-179 Pt2: 
      
      Lamp cover for Thomson mirror speaking galvanometer, made by Elliott Brothers, Strand, London,

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Thomson mirror speaking galvanometer, made by Elliott Brothers, Strand, London, England, 1858 (Pt1); Lamp cover for
Science Museum Group Collection
© The Board of Trustees of the Science Museum

1925-179 Pt 1 (right hand object): Thomson mirror speaking galvanometer, made by Elliott Brothers, Strand, London,
Science Museum Group Collection
© The Board of Trustees of the Science Museum

Thomson mirror speaking galvanometer, made by Elliott Brothers, Strand, London, England, 1858 (Pt1); Lamp cover for
Science Museum Group Collection
© The Board of Trustees of the Science Museum

1925-179 Pt2: Lamp cover for Thomson mirror speaking galvanometer, made by Elliott Brothers, Strand, London,
Science Museum Group Collection
© The Board of Trustees of the Science Museum

1925-179 Pt2: Lamp cover for Thomson mirror speaking galvanometer, made by Elliott Brothers, Strand, London,
Science Museum Group Collection
© The Board of Trustees of the Science Museum

Oil lamp base for Thomson mirror speaking galvanometer, made by Dietz and Company, City of London, England, 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. Instruments of this type were used on the Atlantic cable expedition of 1858. The mirror galvanometer became the standard instrument for receiving telegraph messages, but it did have a disadvantage in that it needed two operators - one to read and call the signal, and another to write the message down. This problem was solved by Thomson when he invented the siphon recorder, which used a glass tube dipped ink to record to movements of the cable on a moving tape, to then be read and decoded.

Details

Category:
Telecommunications
Object Number:
1925-179 Pt6
Materials:
metal (unknown) and textile
type:
oil lamp
taxonomy:
  • furnishing and equipment
  • furnishing - artefact
  • lighting device
  • lamp - lighting device
credit:
Donated by the Eastern Telegraph Company