26 ELECTRICAL [ TELEMETERING ] SYSTEMS CONSISTING ESSENTIALLY OF LIQUID LEVEL MEASURING GAUGES, [ FREQUENCY METERS, RESONANCE-TYPE RESPONSIVE GAUGES, ] FUEL MEASURING INSTRUMENTS FOR AIRCRAFT DROP TANKS, LIQUID CONTENT GAUGES, ELECTRONIC SELECTION CIRCUITRY; AUTOMATIC FUEL FEED CONTROL AND SWITCHING APPARATUS, TIME DELAY APPARATUS FOR CIRCUIT CONTROL, VOLUMETRIC GAUGES FOR CONDUCTIVE LIQUIDS, AIRCRAFT AND SPACE FLIGHT INSTRUMENTS, [ VOLTAGE CONTROL OSCILLATORS, ] TORQUE MONITORS, MASS FLOWMETERS, ILLUMINATED DIALS OR COUNTERS, APPARATUS FOR MEASURING AND CONTROLLING FLUID/AIR RADIO IN GAS TURBINES, DENSITOMETERS, [ RADIOMETERS, AND MERCURIAL CAPACITORS ] FOR MEASURING TEMPERATURE [ , PRESSURE AND OTHER PARAMETERS ]