26 AIRCRAFT INSTRUMENTS-NAMELY, ACCELEROMETERS, AIR SPEED INDICATORS, ALTITUDE INSTRUMENTS, ANGLE OF ATTACK INDICATORS, COMPASSES, MACHMETER INDICATORS, PITOTS, PRESSURE GAGES, PICKUPS, SEXTANTS, TACHOMETERS AND SYNCHROSCOPES, VERTICAL SPEED INDICATORS, NAVIGATING DEVICES, ASTRO-TRACKERS AND OPTICAL INSTRUMENTS