Aircraft for locomotion via air

audio equipment; namely, sound amplifiers

SCIENTIFIC INSTRUMENTS, EQUIPMENT AND APPARATUS-NAMELY, OCEANOGRAPHIC UNDERWATER HOUSINGS, AMPLIFIERS, GEOPHYSICAL AND METEOROLOGICAL MEASURING AND RECORDING DEVICES AND CONTROLS FOR SAME, TEMPERATURE RECORDERS, FLOWMETERS, OCEANOGRAPHIC SEA-BED DRIFTERS, COMPASSES, CHART DRIVES, RECORDERS, BUOYS, BEACON LIGHTS, AND INSTRUMENT TOWERS