26 ARTIFICIAL HORIZON INDICATING APPARATUS FOR USE IN MARINE, LAND, AND AEROSPACE VEHICLES; TRACKING SYSTEMS; COMPUTERS; DATA ACQUISITION, REDUCTION, AND PROCESSING SYSTEMS FOR USE IN MARINE, LAND, AND AEROSPACE VEHICLES; STABILIZATION, GUIDANCE, RATE AND DYNAMIC CONTROLS FOR MARINE AND AIRBORNE VEHICLES; LASERS; MASERS; SONAR; RADAR; CAMERAS; TELEMETERING APPARATUS; ELECTRONIC AND INSTRUMENTATION TEST EQUIPMENT-NAMELY, TELEPHONE TEST EQUIPMENT AND TEST EQUIPMENT FOR GYROCOPIC EQUIPMENT; ELECTRICAL AND OPTIONAL ANALYZZERS; OPTICAL LENSES; AND REFERENCE INSTRUMENTS FOR AIRCRAFT, MISSILES, FIRE CONTROL AND SURVEYING-NAMELY, GYROSCOPES, TURN AND BANK INDICATORS, AUTOMATIC PILOTS, AIRCRAFT INSTRUMENTS, AND ATTITUDE AND HEADING REFERENCE SYSTEMS