Rawson "micro-amp meter" ammeter

Datecirca 1930

Inventory Number0428

ClassificationAmmeter

Subject

Maker Rawson Electrical Instrument Company 1918 - 1968

User Department of Physics, Harvard University founded 1884

User Emory Leon Chaffee 1885 - 1975

Cultural Region

Place of Origin

Place of Use

Dimensions8 × 11.1 × 14.5 cm (3 1/8 × 4 3/8 × 5 11/16 in.)
blue board box: 11.4 × 38.4 × 31.1 cm (4 1/2 × 15 1/8 × 12 1/4 in.)

Material

DescriptionA micro-amp meter, housed in a rectangular, hinged, black metal case. The instrument has three binding posts on the bottom side, marked, "+," "10," and "100."

The face of the instrument has a fan-shaped display window, through which can be seen a scale, marked from 0-10, and a needle-shaped indicator. An arc-shaped mirrored strip is below the scale, and printed below the strip is, "MICROAMPERES / NO. 5716 / RAWSON ELECTRONIC INSTRUMENT CO. / CAMBRIDGE, MASS. / EACH RANGE / RES 2000 OHMS , AT 20° C / PATENTED"

A cylindrical housing is mounted on the face of the instrument, and is marked with a logo: the letter "R" inside a shield design. Two rounded, bakelite adjustment knobs with knurled edges, located on the housing, are marked "ZERO" and "CLAMP"

A small rectangle is painted in the upper left corner on the instrument face.

Signedprinted below mirrored strip: MICROAMPERES / NO. 5716 / RAWSON ELECTRICAL INSTRUMENT CO. / CAMBRIDGE, MASS. / EACH RANGE / RES 2000 OHMS , AT 20° C / PATENTED

Curatorial RemarksSee Provenance.

FunctionTo measure electrical current in a circuit, in micro-amperes.

ProvenanceFrom Cruft Laboratory, 1956. green triangle indicates it was in the Cruft Laboratory stock room or instrument room. Orange rectangle was painted by David Wheatland to mark special meters received for E.L. Chaffee.