Gyroscopic erector, 188 mounting of camera, 187 stabilizer, Gray, 190 Hardener, acid, 262 Hand operation of deRam camera, 121, 125, 129 Haze, 15, 30, 223, 233, 239 Head resistance and weight, equivalent, 156 Heat, effect of on plate sensitiveness, 175, 232 Heater, electric, in camera, 142, 174, 232 Horizon, photography of to indicate inclination, 174 position of, 30 Hurter and Driffield sensitometric curve, 227 Illumination of field by lens, 50, 54, 56, 57 Image of point source, size of, 49, 54, 56 size of in relation to focal length, 59 Incidence, angle of assumed by plane at high altitudes, 206 Inclinometer, 33, 35, 171, 173 Indicators, distance, 163, 295 Inertia, 229, 257 Installation, camera, 24, 208 Instructions, operating, to be placed on apparatus, 42 Instruments, airplane, 30 Instrument board, 30 photographing, 170 Intensification of aerial negatives, 262 Intensity of daylight, 222 Interpretation of aerial photographs, 17, 40, 351 Interval between exposures, 40, 158, 305, 307 for stereoscopic pictures, 334, 338 methods of regulating, 124 Isochromatic plates, 233 Italian photographic practice, 122, 377 Jamming of cameras in operation, 119, 120 K_{1} and K_{2} filters, 239 Keeping power of developer, 259 Kites, 15, 16, 18 Laboratory, mobile photographic, 269 Landscape gardening, use of aerial photography in, 395 Latitude of plates, 229 Lens, 42, 39, =44=, 383 aperture, 39 characteristics, 46 mounts, 65 suitable for aerial photography, 62 symmetrical, 52 telephoto, 61 testing and tolerances, 52 unsymmetrical, 52 wide angle, 62 Levels, spirit, on camera, 95 Light, distribution of in aerial view, 221 trail method of testing camera mountings, 183 Loop, centrifugal force in, 29 Machine gun ring as camera mount, 321 Magazines, =87= bag, 88, 101 Bellieni, 92 Chassel, 92 deMaria, 89, 98 Ernemann, 89 Folmer, 90 Fournieux, 92 Jacquelin, 92 Piserini and Mondini, 90 Ruttan, 92 Magazine racks, 94 installation of, 217 Mapping, 64, 135, 185, 186, =304=, 401 precision, 317, 404 Maps, mosaic, 17, 39, 64, 314 sketch, 314 Marking of negatives, 278 Metol-hydrochinon developer, 261 Mirrors for oblique photography, 324, 326 Monoplane, 24 Motions of camera, 179 Motive power for aerial cameras, =145= Mounting, camera, 102, =103=, 179, 183 384 bell-crank, 120, 198, 203 Brock, 139, 207 center of gravity, 205 floor, 195 G. E. M., 138, 207 Italian, 207 outboard, 194 parallel motion, 198 pendular, 185 tennis ball, 196 Mounting, camera, turret, 312 of prints, 316 of stereograms, 346 Movement, of film during exposure, 75, 142 of image, permissible, 68 Moving pictures from plane, 350 Mud splashing on camera, 214 Naval aerial photography, =368= Negative lens sight, =168=, 299, 305 Night photography, =386=