Galvanometers
Astatic Galvanometers
Astatic Galvanometers are precision instruments used to detect small electric currents by generating a magnetic field. Thereby changing the direction of a suspended compass needle. From measuring the deflection of the compass needle from true North, the electric current can be detected, as well as it's relative strength (if needle moves completely around, the charge is greater- if the needle barely moves, the charge is smaller). As telescopes first showed us the macro world, astatic galvanometers first showed us the micro world. This instrument was a first for sensitive and quantitative electrical data, paving way for the incredible advancements in electron studies and technological innovations ever since.
Circa 1880-1900
Astatic Galvanometer by A.P. Gage
Original paper face is numbered 0-90-0-90, and reads: 'The Astatic Needle is used only when the Galvanometer is required to be very sensitive. Resistance 0.43 ohm.' Astatic Galvanometer signed 'A.P. Gage, Boston'. Galvanometer sits atop a Mahogany base, on three adjustable brass legs. With fitted, hand-blown antique glass cloche.
Featured at the Hampden-Sydney College.
circa 1880-1900
Astatic Galvanometer by Central Scientific Co.
Made by Central Scientific Company. Good condition. Galvanometer with magnetized needle above and in fixed coils. An aluminum pointer attached to needles is suspended by a thread above paper scale graduated from 0°-90°-0°-90°-0°. L-shaped brass suspension support. Coils rest on circular brass base, with two binding posts and three leveling screws. A bell jar enclosure covers the meter.
Tangential, Single-Current, & Unipivot Galvanometers
Tangent Galvanometer's built on this concept and were designed to deflect the compass needle when electrical currents are passed through the vertical copper coils. Single-current Galvanometers operate with a single coil.
circa 1945
Tangent Galvanometer by W.B. Nicolson
Antique Tangent Galvanometer. Irish made, circa 1945. Signed 'W.B. Nicolson, Scientific Instrument Maker, Glasgow'. Composed of wood, brass, and glass. 9 turns on front (three knobs), 50 turns on back (two knobs). Displayed in glass cloche. Mirrored dial is numbered 0-90-0-90, original steeled needle. Base sits atop three adjustable brass legs.
Similar Model Featured in The Science Museum Group.
circa 1920-1940
Unipivot Galvanometer by Cambridge Instrument Co. Ltd.
Beautiful, high quality instrument for the detection of minute electrical emf originally created by the military during World War 1 for blasting and signaling. Features a spring-mounted universal pivot. Moving coil effectively floats on fine spring, protected by a plunge pin in the base that frees the coil on a flat, stable base.
Circa 1900
Unsigned Single Current Galvanometer
Unsigned Galvanometer. Made of Walnut and lacquered brass. Marked 90-0-90. Half-blue steeled needle, with Ruby pivot. Original glass.
circa 1920
Telegraph Works Galvanometer
For single current type ( 22ohms) with 2 brass terminals, 4 quadrant scale 0-90, and compass type pointer. Would have been used by engineers testing lines for the Post Office in conjunction with a Wheatstone Bridge. British made, circa 1920.
Signed 'Teleworks, Silvertown London, No. 2752'.
No-Serial Model Featured in the Powerhouse Collection.
Circa 1920-1940
Dollar Tangential Galvanometer
English or American made, circa 1920-1940.
Similar Model Featured in the Science Museum Group.