DC ammeter with five ranges
Date1940-1970
Inventory Number1997-1-1085
ClassificationAmmeter
Subject
Maker
General Electric Company
1892-present
User
Department of Physics, Harvard University
founded 1884
Cultural Region
Place of Origin
Dimensions8.8 × 13.4 × 20 cm (3 7/16 × 5 1/4 × 7 7/8 in.)
Material
Accessoriesleather case
DescriptionAn ammeter consisting of a black metal box with five electrical connectors near its bottom (labeled +, 50, 150, 300, 500, and 1000), the two rightmost having plastic caps. Over the connectors is a large window, behind which is a metal plate marked with an arc-shaped scale curving in the opposite direction to the connectors. Two ranges are marked on the scale, from 0 to 50 in red, and from 0 to 150 in black. There is a reflecting band directly above the red scale. A thin metal needle hovers above the scale, originating from the covered part of the box.
The metal box fits in a leather case with a lid that uncovers the bottom half of the instrument containing the window and connectors. This leather case also has round holes on the sides near the back of the instrument where screws protrude from the ammeter.
The metal box fits in a leather case with a lid that uncovers the bottom half of the instrument containing the window and connectors. This leather case also has round holes on the sides near the back of the instrument where screws protrude from the ammeter.
Signedabove scale: GENERAL ELECTRIC / MADE IN U.S.A. / D.C. MICROAMPERES
Inscribedsmall print above scale: NO. 3727013 TYPE DP-9
inside of lid handwritten in green: 244
Curatorial RemarksN.P. 71722.
FunctionAn ammeter for direct currents with five different ranges, from the very smallest up to one amp.
ProvenanceFrom the Department of Physics, Jefferson Laboratory, Harvard University.
Weston Electrical Instrument Corporation
Date: 1920-1930
Accessories: standardization card from the A.S. Mancib Co.
Object number: WJ0951
Weston Electrical Instrument Corporation
Date: 1900-1930
Accessories: standardization certificate on inner surface of lid
Object number: 1997-1-1183
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: circa 1913
Object number: 1997-1-0328
Weston Electrical Instrument Corporation
Date: 1901-1930
Accessories: standardization certificate on inner surface of lid
Object number: 2003-1-0038