Signedplaque: MADE BY THE / WESTON ELECTRICAL INSTRUMENT CORP / NEWARK, N.J. / U.S.A. / PATENTED / JAN [illegible] 95, MAR 25 98, OCT 3[5?] 98 / OTHER PATENTS PENDING / MODEL 155 / No. 65945
Inscribedbelow scale: AMPERES A.C. / AMPERES FOR FULL SCALE=15
below screw: CORRECTION
written with black ink over green background: E 1981 / N(U?).S.G. / STOCK
FunctionThis is an ammeter for AC current. It most likely works by deflection of its needle by a magnetic field generated at a coil through which the current to be measured passes.