26 [ SONIC DEPTH SOUNDERS, RADIO DIRECTION FINDERS, ] MARINE ENGINE SYNCHRONIZERS, [ FIELD GLASSES, SPORT GLASSES, OPERA GLASSES, ] BAROMETERS, THERMOMETERS, HYGROMETERS, COMBINATION HYGROMETER-THERMOMETER, COMBINATION THERMOMETER-HYGROMETER-BAROMETER, TACHOMETERS, COMPASSES, ALTIMETERS AND SPEEDOMETERS