(n.) An instrument for measuring the intensity of light\, or, more especially, for comparing the relative intensities of different lights, or their relative illuminating power.

Bourdon tube Gyropilot Gyrosin compass HFDF Mach meter RDF absolute altimeter accelerometer aerial reconnaissance camera aerometer aeroscope air log altigraph altimeter ammeter anemograph anemometer anemoscope aneroid automatic pilot autosyn barometer bombing locator bombsight calorimeter card compass chronometer compass control rod evaporimeter flight recorder galvanometer gosport gosport tube gyrocompass gyroscopic compass gyrostatic compass horn hub dynamometer hygrograph hygrometer hypsometer inclinometer induction compass inertial navigation system joy stick loran magnetic compass magnetic needle meteorograph micrometer needle octant optical altimeter ozonometer photometer pitot-static tube pluviometer potentiometer pyrometer quadrant radar radio radio compass radio direction finder radiogoniometer rate-of-climb indicator recording hygrometer robot pilot sextant shoran spirit level static tube sting strike radar scanner sun compass tachometer thermograph thermometer thermostat throttle transit instrument variometer venturi tube viscosimeter wireless compass yoke