Signedbelow scale: WESTON D.C. MICRO-AMMETER
on standardization certificate: WESTON D.C. MICROAMMETER, MODEL 45 (322 striked through)
on plaque: MADE BY THE / WESTON ELECTRICAL INSTRUMENT CO. / NEWARK, N.J., U.S.A. / PATENTED / [9 patent dates] / MODEL 45 No. 29111
Inscribedaround screw: 0 / CORRECTION
in white paint on box: DC AM / 000500
FunctionAn ammeter for measuring very small direct electrical currents. It is most likely a galvanometer type. Seems to be designed for portability.
ProvenanceFrom the Department of Physics, Harvard University.