Thomson indicating wattmeter
Date: date 1896
Inventory Number: 0423
Classification: Wattmeter
Dimensions:9 × 16 × 14 cm (3 9/16 × 6 5/16 × 5 1/2 in.)
DescriptionA General Electric indicating wattmeter in a fan-shaped black metal case, mounted on a square wooden base. The face of the meter has two heavy binding posts and three cylindrical bakelite posts (one marked "75") and two push buttons. The instrument case has a protuding half-dome centered at the bottom, beneath which the instrument coil is housed.
The instrument has an irregular, fan-shaped display window, through which the instrument's scale and a needle-shaped indicator may be seen. The scale has two sets of calibrations, one from 0-75 and the other from 0-150. Below the scale is an arc-shaped reflecting mirror.
Description from original card: "Small fan shaped meter black metal case on a rectangular wood base with two heavy current binding posts and 3 smaller bakelite posts (one marked 75) and two press buttons. Scale 4 1/2'' paper with strip mirror & 2 hand calibrated scales one 0-75 and above it 0-150 each cramped at both ends. Knife edge pointer. Another identical instrument 0561 (54615)."
Signedprinted on instrument display: GENERAL ELECTRIC INSTRUMENT CO.
Inscribedprinted on base of scale: THOMSON INDICATING WATTMETER / NO. 54514 / POTENTIAL LIMIT 150 VOLTS / CURRENT LIMIT 2 AMPS. / GENERAL ELECTRIC CO. / SCHENECTADY, N.Y. U.S.A. / PATENTED FEB. 11 '96;
binding post marked: 75
FunctionMeasures the power consumption of a circuit.
Historical AttributesBlue triangle indicates that this instrument was used for teaching in the Physics Department, course Physics 3, in the 1920s.
ProvenanceFrom the Physics Department, Harvard University. Jefferson Laboratory. 12/11/63.