EXPLORATION AND MAPPING
Aerial photographic mapping in war-time has been almost entirely
confined to inserting new details in old maps. For such work some
distortion or a lack of complete information on altitude and directions
is not a serious matter, because the known permanent outlines serve as a
basis. Furthermore, in so far as outline maps are concerned, as
distinguished from pictorial maps, these have been drawn on the ordinary
scales, and with the ordinary conventions of engineering map practice.
Aerial photography may be used in the future in practically the same
way, as an aid to the quick recording of those minute details which
would ordinarily consume an enormous amount of labor to survey directly.
The region shown in Fig. 200 affords a good illustration. A discouraging
amount of time and effort would be required to map this section of
Virginia by the usual methods, while the smallest curve of creek and
shore is instantly and completely recorded on a single photographic
plate. But there are other possibilities, diverging from this
application both toward greater and lesser requirements for precision.
Pictorial maps, in which the actual photographs figure, promise to be an
essential part of the airman's equipment, whether he be pilot or
passenger, mail carrier or sportsman. Without any pretention to detailed
accuracy of location, these maps will show, in strip or mosaic form, the
general appearance of the country to be traversed, with particular
reference to good landing fields and other points of interest to the
aviator. Vertical pictorial maps may be supplemented by obliques giving
the view ahead, whereby the pilot may direct his ship. Thus the
Washington monument as seen by the pilot from Baltimore is a truer guide
than is the country beneath him. The crossing of mountain ranges is
another case where the oblique picture will be more useful than the
vertical (Fig. 201).
[Illustration:
FIG. 200.—An aerial photographic survey of ground difficult to cover
by ordinary surveying methods.]
[Illustration:
FIG. 201.—Seeking out mountain passes.]
Contrasted with the merely pictorial maps will be precision surveys.
Whether it will prove practical to make these entirely from the air is
still an open question. It is to be assumed that cameras can be
constructed with lenses having negligible distortion of field, with
between-the-lens shutters to obviate the distortions due to the
focal-plane type, with auxiliary devices for indicating compass
direction, altitude, and inclination, or with gyroscopic mounting so
that an inclination indicator is unnecessary. The application of aerial
photography to precision mapping will depend upon the perfection which
such cameras attain, as estimated by the permissible errors in this form
of mapping. Entire dependence on photography, as in uncharted regions,
is likely to be worked up to slowly, beginning with a stage of rather
complete triangulation of natural or artificial points—say three in each
constituent picture—then through several stages each successively
employing fewer and fewer well determined points. The photographic
mapping of some of our Western States will be greatly facilitated by the
100-yard squares into which the land is divided and already marked in a
manner which shows clearly in aerial photographs.
A theoretical possibility is the plotting of contours from stereo-aerial
pictures. Given two elements of a stereoscopic pair, taken from points
whose separation is known, the position of any point in space shown in
the stereoscopic view can be determined by the use of the
stereo-comparator. This is an instrument already employed in mountain
photo-surveying, which consists essentially of a compound stereoscope in
whose eye-pieces are two points movable at will so that the relief image
formed by their fusion can be made to coincide with any chosen part of
the landscape. The chief difficulty in the application of this idea to
aerial work is to fix the base line. This problem may be met in some
cases by using stereo obliques, and getting the base line by
simultaneously made vertical photographs of well surveyed territory
beneath. Possibly also methods can be developed by which photographs
from two or more known altitudes may furnish the requisite data.
[Illustration:
FIG. 202.—Business section of Hampton, Virginia. A survey made by a
single instantaneous exposure.]
[Illustration:
FIG. 203.—Mosaic map of the City of Washington. White rectangle shows
portion included in next figure.]
[Illustration:
FIG. 204.—Portion of Washington mosaic, full size.]
City mapping is a field for which aerial photography is peculiarly
fitted (Fig. 202). A complete map of a large city is a labor of years.
In fact, a modern city is always dangerously near to growing faster than
its maps. An aerial map, on the contrary, can be produced in a few
hours. Paris was mapped with 800 plates in less than a day's actual
flying. Washington was completely mapped in 2½ hours, with less than 200
exposures. The entire map is shown, on a greatly reduced scale, in Fig.
203, while Fig. 204 shows a small portion of it in full size, from which
can be obtained an idea of the dimensions of the original. These maps,
while not accurate enough for the recording of deeds and mortgages, yet
serve the majority of needs. There is indeed no reason why with long
focus cameras, given several accurately marked points, the photographic
map of a piece of real estate should not be made with all the accuracy
needed, still leaving the whole process of partial surveying helped out
by photography an enormously simpler one than the usual method.
Rougher types of surveying, in open country, offer a most promising
opportunity. Railway surveys, showing the character of the country:
passes through mountain ranges: the available timber and other materials
of construction. Canal routes, with the available sources of water
supply, and the best choice of course to avoid deep cuttings and
aqueducts. Irrigation projects, with the natural lakes, river courses
and valleys, which may be dammed to form storage basins. Coast, river
and harbor surveys are possible by aerial means with a promptness and
frequency which should entirely revolutionize the making of maps of
waterways. Shifts in channels and shallows, even of considerable depth,
stand out prominently in the aerial photograph. The actual bottom, if
not more than three or four meters down—as in a bathing beach—shows in
the aerial photograph (Fig. 193), while the varying surface tints caused
by light reflected from the bottom at far greater depths are readily
differentiated by the camera from the air. An instantaneous photograph
will thus perform the work now done by a week's soundings. Fig. 205,
taken near Langley Field, shows how the aerial photograph may be used to
chart natural channels, while Fig. 206 shows the dredged channels of the
port of Venice. Navigation of such a river as the Mississippi with its
shifting bars may come to be guided by monthly or even weekly aerial
photo maps.
[Illustration:
FIG. 205.—Shallows and channels revealed by the aerial photograph.]
[Illustration:
FIG. 206.—Venice from the air, showing dredged channels.
Italian official photograph.]
[Illustration:
FIG. 207.—Bengasi, a North African town, surveyed for the first time
from the air.
Italian official photograph.]
[Illustration:
FIG. 208.—Thurnberg on the Rhine.
Photograph by photographic section A. E. F.]
Among other uses for aerial photography will be the location of timber.
As one illustration, may be taken the discovery of mahogany trees. Their
foliage at certain times of the year is of characteristic color. This
may be recorded on color sensitive plates with a scientifically chosen
filter, and the cutting expedition sent out with the photograph as a
guide. In this as in other cases where rough or unexplored country is to
be covered, it is a question whether the airplane will after all be the
most feasible craft, on account of its necessarily rapid rate of travel,
and its need for known landing fields. The dirigible of large cruising
radius, which can seek its landing field at leisure, is probably
indicated for this kind of work. It may indeed, as already hinted, prove
to be the chief photographic aircraft of the future.
Archæological surveys offer a fascinating opportunity for airplane or
dirigible balloon photography to render scientific service. Buried in
desert sands or overgrown with tropical vegetation the ancient cities of
Asia Minor, of Burma, and of Yucatan evade discovery, and even when
found remain unmapped for decades. Discovery and mapping can now go
hand-in-hand. The topography of barbaric or colonial towns and villages,
whose importance could not warrant elaborate surveys, but which should
nevertheless be a matter of record, will be quickly and easily plotted
by photography (Fig. 207). To this day who knows how the streets run in
Timbuctu, and how, save from the air, can we ever map the teeming cities
of China? He who would follow in the footsteps of Haroun-al-Raschid can
even now explore the by-ways of Bagdad by the aid of the Royal Air Force
photographic map!
INDEX
Aberrations, lens, 47, 54
Aberration, spherical, 47, 54
chromatic, 48, 54
Acetylene light, 284
Advertising, use of aerial photography in, 392
Aero 1 and Aero 2 filters, 241
Airplane, as camera platform, =20=
types of, 24
Air speed, 27, 308
indicator, 33, 34
Alcohol, use of in plate drying, 275
use of in print drying, 286
Altimeter, 33, 174
reading recorded on film, 135, 171
Altitudes of flight for photography, 61, 224
Anastigmatic type of lens, 47
Aperture, lens, 39, 44, 56, 57
Archæological surveying, 413
Astigmatism, 49, 50, 54
Auxiliaries, camera, =163=
installation of, 214
Bagley camera, 286, 314
Balance, of camera, 96
of plane, 157, 208, 217
Balloons, 15, 16, 18
Banking, 27, 324
Batteries, storage, 150, 156
Bay, camera, 120, 210
Bellows, camera, 65, 95
Biplane, 24
Blast marks in front of guns, 363
Bleaching out print to leave interpretation marks, 367
Boat, flying, 25, 374
Bowden wire, 103, 106, 108, 111, 114, 116, 118, 126, 129, 136, =163=
Brightness, range of, 221, 225
Burchell photographic slide rule, 303, 339
Camera, airplane, =39=, 384
automatic, 18, 43, 90, 116, =124=, 125, 311
B. M., =120=, 203
Bagley, 286, 314
Brock automatic plate, =126=
C type, 43, 87, 103, =109=
classification of, 43
deMaria, 86, 89, 103
deRam, 82, 93, =121=, 129, 157, 205, 214, 326
E type, 43, 87, 103, =109=
elements of, =42=
film, _see_ Film cameras
Folmer automatic plate, =126=
hand held, =95=, 321, 369
English, =99=
German, =99=
U. S. Air Service, =100=
Ica, =103=
Lamperti (Italian), =112=, =211=
L. B., =120=
long focus, 103, 301, 324
L type, 43, 82, 94, 102, =117=, 162, 210
M., =106=, 203
non-automatic, 43, =102=
Piserini and Mondini, =111=
semi-automatic, 43, =116=, 149
stereoscopic, 341
Camouflage, filters for the detection of, 225, =243=
stereoscopic views and, 329, 358
Ceiling of plane, 27, 130
Channels, detection of by photography, 408
Chemicals, photographic, =257=
Chlorhydrochinon developer, 261
Chromatism, lateral, 49, 54
City planning, use of aerial photography in, 396
Clock-work for driving cameras, 149, 155
Clouds, 224, 242
Collimator, 66
Color, coefficient or index of negative, 259
filters, _see_ filters
photography, =385=
sensitive plates, 15, 174, 233, 237
sensitiveness of film, 131
sensitizing, methods of, 235
Coma, =47=, 48
Communication, means of on plane, 296
Compass, 33, 173
reading recorded on film, 135, 171
Cone, camera lens, 42, 114
interchangeable, 108, 120
Construction operations, aerial photographic records of, 396
Contact, imperfect in printing, 279, 284 prints, 45, =279=
Contacts, electric, on plane, 163
Contours by stereo aerial photography, 404
Control, distance, of camera, 110, 163
speed, of camera, 136, 144, 157
Controls, duplicate, 19, 25, 195, 209, 214
of plane, 21, 26
Convergence point, 337
Cord for adjusting shutter aperture, 82
Core rack development, 271
Contrast, in brightness on earth's surface, 221
in photographic emulsions, 15, 230, 236, 258
Counter, exposure, on magazine, 88
on release, 164
Covering power of lens, 44, =49=, 50, 58
Crabbing, 27, 308
Cradles, camera, 195
Cross wires, 23
insertion of camera through, 42, 210
Curtain, auxiliary shutter, 80, 84, 106
speed of travel of shutter, 74
uniformity of, 76, 82, 84, 86, 315
Cylinders, relation between vibration and number of, 185
Dark slides, double, 87, 99
Daylight, intensity of, 222
Definition, lens, 44
Density, of air, effect of on propeller, 154
of photographic image, 228
Developers, for plates and films, =257=, 260
for papers, =262=
Developing machines, film, 133, =273=
Ansco, 273
Brock, 274
Eastman, 274
G.E.M., 273
Development, core rack method of, 271
factor, 228
film, =272=
methods of, =267=, 269
of prints, =286=
speed of, 236, 267
tank, 270
time, 269
DH-4 plane, 210, 217, 296
photographic, 213
DH-9 plane, 296
Diaframs, to equalize illumination of plate, 78
lens, 48, 58
Dilution coefficient of developer, 258
Dirigibles, 15, 16, 413
Distortion, absent with between-the-lens shutter, 74
barrel, 51
due to camera tilting, 206, 286, 305, 315
in aerial maps, 317
lens, 39, 44, 51, 54, 56, 62
pin-cushion, 51
produced by film shrinkage, 237
produced by focal plane shutter, =74=
produced by glass plate in front of film, 131
with wide angle lenses, 63
“Dodging” in printing, 279, 315
Doors in plane for camera to work through, 214
Drying of films, =267=, 276
of plates, 267, 275
of prints, =286=
Earth, appearance of from plane, 30
Eastman apron film developing machine, 274
twin reel film developing machine, 274
Efficiency, propeller, 155
shutter, 70, =72=, 76
English aerial photographic practice, 45, 46, 283, 291, 340
EK filters, 241
Electric, drive for cameras, 116, 119, 123, 145, 149
generator operated by motor, 146
motor, characteristics of, 151, 156
motor, service, 163
Elevation possible to detect in stereoscopic views, =340=
Emulsions, photographic, characteristics of, =227=
Enlarging, 45, =279=, 283
camera, 283
Enlarging versus contact printing, 59
Exhaustion of developer, 259
Exploration, use of aerial photography in, 401
Exposure, data charts, 250
distance between for mosaic maps, 307
distance between for stereos, 336
estimation of, 248
limitations to, 247
meters, 251
meter, Wynne, 251
of aerial negatives, =247=
relation between motion of plane and, 68, 185
under, period, 230
Field, angular, of lens, 57, 302
flatness of lens, 56
Field laboratory, mobile, 268
Film cameras, 43, =130=, 134
Brock, 138
Duchatellier, 131, 136
F type, 134, 171
G.E.M., 138
German, 64, 76, 139, 317
K type, 142, 203, 214
Film, celluloid, 130
backed, 133
changing in the air, 137, 144
color sensitiveness of, 237
cut, 275, 278
development of, 130, 272
drying, 131, 276
means for holding flat, 130, 131
relative performance of compared to plates, 237
satisfactory kinds for aerial work, 238
shrinkage, 237
Filters, 15, 58, 106, 174, 224, 233, =239=, 241, 243
effects secured by use of, 241
Filters, gelatin, 244
glass, 245
holders for, 67, 106, 224
ratio, 240
Fixing bath, 262
Flaps, auxiliary to shutter, 80, 84, 85, 98, 99, 101, 119
to protect lens, 214
Flash lights, 18, 386
Flying boat, 374
Focal length, relationship of lens characteristics to, 55, 57
requirements for, 39, 42, 58, 61, 103
Focal plane, 50
shutter, 70, 71
distortion by, 74
performance of, 86
types and representative, 80
Focus, depth of, 44
effect of temperature on, 41, 65
fixed, in aerial cameras, 40
ground and air, 65
Focussing, automatic, 284
by parallax, 65, 66
Fog, atmospheric, 224
photographic, 237, 258
French aerial photographic practice, 45, 46, 283
Friction disc speed control, 136, 159, 160
Fuselage, 21, 87
shape and size depending on type of engine, 23
Future of aerial photography, =383=
German aerial photographic practice, 63, 103, 209
Glass, optical, used in lenses, 44
Gloves, handling apparatus through, 41, 89
Governor for camera speed, 159
Graphite, use of to prevent static discharge, 134
Gravity, action of in aerial cameras, 41, 112, 115, 119
center of, should not change in cameras, 125, 207
change of center of, in magazines, 92, 112
depended on in magazines, 88
handles best at center of, 96
pseudo, in moving vehicle, 188
support at center of, 182, 203
Ground speed, 27, 307
indicator, 311
Guide-books, illustration of, 15, 392
Guides for inserting magazines, 41
Gyroscope, 189
Gyroscopically controlled instruments, 29, 174, 192, 312
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=
Numbering devices in cameras, 169
Oblique views, 39, =320=
angles at which taken, 40, 321
exposures for, 69
filters for, 242
use of hand cameras for, 95
Observer, function of in aerial photography, 291, 295, 304
Oil spray from motor, 214
Opacity, 228
Opening for camera, 211
Opposite directions, shutter to move alternately in, 76, 139
Orthochromatic plates, 233
Overlaps, for mapping, 307
for stereoscopic views, 40
on a turn, 64, 139
Panchromatic emulsions, 233
plates, 49, 238
Panoramic views, 321
Parallax method of focussing, 65, 66
Parallel, flying in, 308
Photographic planes, special, 213
Pilot, function of, in aerial photography, 291, 295
Pinpoints, 39, 291
Pistol grip for hand cameras, 95, 96
Plate holders, 87
Plates, bathed, 235
behavior of compared to film, 237
color sensitive, 233
iso- and ortho-chromatic, 233
panchromatic, 233
satisfactory kinds for aerial work, 238
self screening, 245
shape of, 63
size of, 43, 62
Plumb line, behavior in banking plane, 28
Ply-wood veneer construction, 23, 211
Positype paper, 238
Potassium carbonate for drying plates, 276
Power required to drive cameras, 125
Pressure, of shutter curtain, 131
plate, for holding film flat, 131, 141
Printing, =279=
contact, 279
machines, 279
media, 252
Prints, paper, 253
development of, =286=
Prisms for oblique photography, 324, 326
Propeller, characteristics, 152
constant speed, 129, 159
drive for cameras, 102, 116, 119, 135, 136, 144, 157, 158
position of, 120
variable speed, 159
Pump, for producing suction on film, 132
Punch marks on film, 144, 272
Pyro developer, 261
Racks, negative, 271
Real estate, aerial mapping of, 393
Rectifying, 286, 305
camera, 314
Reduction of aerial negatives, 262
Release, shutter, 96, 99
duplicate, for pilot, 164
Release, shutter, time controlled, 124
Relief, criterion for correct, 335, 344
exaggerated, 337
impression of, produced by motion, 349
Resolving power of plates, 59, =235=, 260
Richard stereo printing frame, 283, 348
Rinsing of plates, 259
Rubber, sponge, use of in camera mountings, 195, 203
Safe lights, photographic, 269
Safety catch on camera mounting, 203
device on camera driving mechanism, 162
Salvaging of ships, aerial photography and, 399
Seaplane, 25, 374
Self screening plates, 245
Semaphore signalling in plane, 297
Semperfocal enlarging camera, 284
Sensitized materials, requirements for, 225
Sensitometry, =227=
of papers, 253
Shadows, compass directions from, 356
proper direction for, in examining prints, 352
Shaft, flexible, 119, 123, 142, 161
Sheaths, plate, 87, 88, 93, 126, 170
Shrinkage, film, 237, 317
paper, 285, 315, 317
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
Veneer construction, 23, 209, 211
Venturi tube, 132, 142, 144
Vibration, 16, 18, 26, 40, 41, 58, 102, 179
Volcanoes, photography of, 15, 399
Water for mixing chemicals, 262
Watkins factor, 258
Weight and head resistance, equivalence, 156
of film compared to plates, 101, 130
of deRam camera, 123
of hand cameras, 96
of K type camera, 144
of K film roll, 144
of L type camera, 117
of M type camera, 109
of storage batteries, 157
Wind, flying against, 68, 308
motor, 146
Windows in side of plane, 214, 328
Wire, barbed, appearance of in aerial photograph, 360
* * * * * *
Transcriber's note:
1. Silently corrected typographical errors.
2. Retained anachronistic and non-standard spellings as printed.