Shutter, 42, 68 between-the-lens, 58, 70, 112, 115, 316, 387 efficiency, 70, =72=, 76 focal plane, 70, 71, 73 focal plane, double for stereo work, 341, 345 focal plane, moving alternately in opposite directions, 76 focal plane, types of, 80 Shutter, Folmer, 80 Ica, 81 Klopcic, 78, 84, 98 release, 96, 99, 124 speed, 39, 40, 58, 70, 249 testing, 76 testing apparatus, 77 Sights, =164=, 166, 296, 301, 327 adjustable for angle of incidence of plane, 169 attached to plane, 167 negative lens, 168, 299, 305 rectangular, 98, 167, 373 stereoscopic, 338 to indicate size of field, 166, 373 tube, 101, 166 Single-seaters, carrying cameras in, 114, 211 Slide rule, photographic, 303, 339 Solenoid, 151, 163 Sound, not to be used for indication in plane, 164 Spacing of pictures in film camera, 144 Speaking tubes on plane, 296 Speed, of development, 236, 267 of plates, 228, 236 criteria of, 230 effect of temperature on, 175, 232 variable, control of camera, 144, 151 Spotting, 64, 125, =291= Spring motors, 149, 155 Springs, use of in aerial cameras, 41 in magazines, 88 Stabilized camera, 95, 187 Static electric charges on film, 131, 133 Stereo-comparator, 404 Stereo-oblique views, 115, 321, 343 Stereoscopes, 331 Stereo printing, 283 Stereoscopic cameras, 341, 344 effect, absence of at flying heights, 30, 334 Stereoscopic photography, 329 mounting, 346 pictures, fusion of without instruments, 330, 343 sights, 338 views, 39, 40, 64 uses for, 348 vision, principles of, 329 Stop-watch attached to shutter release, 310 Strap, on hand camera, to go around observer's neck, 99 on plate magazine, 87 to go over hand, on hand camera, 100 Stream lines, 26 lined hood, 214 Suction for holding film flat, 131, 132, 142 advantages of continuous and intermittent, 132 Surveying by aerial photography, 401 Tank development, 270 Tearing edges of prints, 317 Telephones on planes, 296 Telephoto lens, 61 Temperature, coefficient of development, 258 effect of on focus, 41 effect of on mechanical functioning, 41, 102, 125 effect of on plate speed, 232 limits of development, 258 Test chart, lens, 52 Threshold value, 230 Thrust, propeller, 152 Timber, location of by aerial photography, 413 Tone rendering, correct, 226, 230, 239 Touch, sense of, not dependable in plane, 41, 125, 164 Trailer, photographic truck and, 268 Transmission of power to camera, 161 Transparencies, 252, 330 Transparency, 227 Trays, camera, 195 Tri-color ratio, 235 Triplane, 24 Tuning fork, used in shutter tester, 79 Turbine, wind, for driving camera, 116, 127, 144, 147, 158 Uniformity of curtain speed in focal plane shutter, 76, 82, 84, 86, 315 Unit system of camera construction, 42 Uprights, camera, in plane, 209 Uses for aerial photography, =388= Velocity constant, 258