GENERAL RADIO CO. GR
STANDARDS OF RESISTANCE, INDUCTANCE, AND CAPITANCE FOR MEASURING PURPOSES, DECADE BRIDGES, SLIDE-WIRE BRIDGES, CAPACITY BRIDGES AND METERS, HOT-WIRE METERS, WAVE METERS, AUDIBILITY METERS, SPECIAL MEASURING INSTRUMENTS FOR MAKING MEASUREMENTS AT AUDIO AND RADIO FREQUENCIES, ELECTRICAL COMPENSATORS FOR SUBMARINE DETECTION AND DEPTH SOUND RANGING, AND D'ARSONVAL METERS
Expired · April 3, 1924 · 71194917 ·