Scientific Instruments

Measuring: Electrical

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Early 20thC bench tangent galvanometer by 'A Gallenkamp & Co Ltd.'. Mahogany case, jewelled bearing and silvered / mirrored dial. Back of case has 5cm 'wings' either side with holes in to affix to desk. Size (excl.wings) 15.5cm square. £68 ($136)

Late 19th C Tangent Galvanometer. Mahogany base with lacquered brass terminals, 3 levelling screws and original glass dome. -Lovely piece of kit! £340 ($680). Total height 22cm, base diameter 17cm.
The Tangent Galvanometer was introduced by Servais Mathias Poullet in 1837. A current flowing through the coils will deflect the needle of the compass. The current strength is proportional to the tangent of the angle of the deflection. The present instrument could be used as a teaching device for physics classes, for demonstration of the tangent law (the relation between the current flowing through the coils and the tangent of the angle of deflection of the compass). Such instruments would also be used to plot the horizontal component of the earths magnetic field in the laboratory-an important consideration in any laboratory where studies involving magnetism are to be conducted.