TitleReflecting galvanometer scale About this objectThis calibrated scale forms part of a reflecting galvanometer, an instrument commonly used in submarine cable work. Within the galvanometer, a beam of light reflects off a mirror attached to the coil. The light then projects onto this scale, indicating a reading corresponding to the deflection of the mirror.
Reflecting galvanometers addressed several limitations of earlier needle-based designs. In conventional galvanometers, the needle had to be kept very short to minimise the effects of the earth’s magnetic field and reduce damping errors caused by the mass of the needle itself. However, a shorter needle also makes a smaller movement along the arc, making precise readings difficult. The reflecting system solved this problem: a minute deflection of the mirror produces a large movement of the light beam on the scale, amplifying small movements for greater precision. In telegraphy, this innovation allowed operators to detect weak signals, measure line resistance, and troubleshoot faults with high sensitivity – a crucial capability in long-distance telecommunications. Object No.99.94SourceLa Perouse MuseumOn displayYesTypeMuseum objectsOrganisations (Detailed entries)La Perouse Museum (La Perouse, N.S.W.)ThemesScience and communication
