ID:
320
Maker's Name:
Kelvin, Bottomley and Baird, Glasgow and London, No. 21109
Where made:
Scotland
Dimensions:
22 × 37 × 48 cm
Housed in rectangular brass case painted black, with glass front, rigidly fixed to wooden base with 3 levelling screws. Aluminium pointer includes 3 weights - 28, 84, 333 mg. Comes with mahogany carry case with brass fittings. "Manufacturer's instructions for use of vertical electrostatic voltmeter" pinned to inside of door. 3 ranges: 2500V, 6000V, 12000V.
Multicellular type electrostatic voltmeter, i.e. movement is in the plane of the attracted conductor. Probably used to measure voltages for trains/trams. Has the useful property that large surges of power through it will not harm it unlike a galvanometer based voltmeter.
T.G.
Book reference:
K. Lyall, Whipple Museum of the History of Science Catalog 8, 1991
R. Glazebrook, Dictionary of Applied Physics, Vol. III, MacMillan & Co., London 1922
