portable galvanometer with moving coil
Datecirca 1889
Inventory Number0223a-e
ClassificationGalvanometer
Subject
Maker
Emile Gérard & Company
User
Department of Chemistry, Harvard University
?
founded 1791
Cultural Region
Place of Origin
Place of Use
Dimensions48.5 × 20.5 × 14 cm (19 1/8 × 8 1/16 × 5 1/2 in.)
Material
Accessoriescoil; case; cover; strings
DescriptionFrom instrument card: "String galvanometer with large moving coil and mirror with kerosene lamp housing and scale, each in separate wooden boxes attached to central, vertical board with handle. Boxes to be mounted on a wall. Set of suspensions attached to underside of #223b."
Brass frame containing coil and small circular mirror mounted on one side of box (0223d). Black painted wood box (0223c) fits into upper part of box and houses replacement parts for wire suspension. Central suspension tube with two circular viewing windows on either side. Plastic ruler mounted along suspension tube (broken in several places). Boxes rest on square wooden base (0223a). Four brass binding posts on one side of box and two binding posts on other side.
Brass frame containing coil and small circular mirror mounted on one side of box (0223d). Black painted wood box (0223c) fits into upper part of box and houses replacement parts for wire suspension. Central suspension tube with two circular viewing windows on either side. Plastic ruler mounted along suspension tube (broken in several places). Boxes rest on square wooden base (0223a). Four brass binding posts on one side of box and two binding posts on other side.
Signedon plate inside case: MÉDAILLE D'OR / EXPOSITION UNIVERSELLE PARIS, 1889 / EMILE GÉRARD & Co / LIÈGE (BELGIQUE)
Inscribed
FunctionThis portable galvanometer was used in measuring very low voltage potentials for calibrating equipment. When a current is applied to the galvanometer, a small variation will create a torque motion on the mirror. A light is then beamed on the mirror, which will be redirected away from the galvanometer towards a graduated scale. The position of the reflected light on that scale will indicate the variation of the current detected by the galvanometer.
ProvenancePossibly from the Department of Chemistry, Harvard University, 1/8/1957.
Leeds & Northrup Company
Date: 1930-1950
Object number: 1997-1-0340
American
Date: circa 1886
Accessories: cover
Object number: 0546
Robert W. Paul Instrument Company
Object number: 2012-1-0013
Leeds & Northrup Company
Date: 1920-1940
Object number: 1998-1-0534
American
Date: 1890-1930
Object number: 0155a,b,c,d
