milli-ammeter
Date1890-1910
Inventory Number0221
ClassificationAmmeter
Subject
Maker
Hartmann & Braun AG
1879 - 1999
Cultural Region
Place of Origin
Dimensions21 x 20 x 11.5 cm (8 1/4 x 7 7/8 x 4 1/2 in.)
Material
DescriptionMoving coil ammeter graduated in milliamperes, with a current lead spring mounted in a bakelite panel with the scale at the top. The instrument is housed in a wooden case with a glass panel at front, and there are two electrical connectors on the front part of the wooden base.
A large metal needle points to the linear scale of 50-0-50 milliamperes.
A large metal needle points to the linear scale of 50-0-50 milliamperes.
Signedon dial: HARTMANN & BRAUN A.-G. FRANKFURT A/M / N° 115906 / D. R. PATENT
Inscribedfront of base marked: 20E142
rear of base marked: 199
front of base: 221
FunctionMeasurement of small electric currents.
ProvenanceFrom the Department of Chemistry, Harvard University.
Jewell Electrical Instrument Company
Date: circa 1931
Accessories: inside lid is a standardization certificate from Oct. 16, 1931.
Object number: 1997-1-0334
Weston Electrical Instrument Corporation
Date: 1901-1930
Accessories: standardization certificate on inner surface of lid
Object number: 2003-1-0038
Marion Electrical Instrument Company
Date: 1937-1959
Accessories: cardboard box; saran wrap
Object number: WJ1263
Weston Electrical Instrument Corporation
Date: circa 1924
Accessories: standardization certificate from Jan 7, 1924 inside lid
Object number: 1997-1-1055