CHAPTER XXXI
FUTURE DEVELOPMENTS IN APPARATUS AND METHODS

Prophecy is an undertaking that always involves risk. The prophet's guess of what the future will bring forth is based only on the tendencies of the past, the most urgent needs of the present, and the activity of his imagination. He may easily—and he usually does—entirely overlook certain possibilities which may arise apparently from nowhere and which profoundly affect the whole trend of development. Conditions which dominate at the present time—such as military necessity—may happily drop into the background and free the science from some of its severest restrictions. With this caution, some future possibilities in apparatus and methods may be presented along the lines already used in discussing the present status of aerial photography.

Lenses.—From the military standpoint the next steps in lens design would be toward telephoto lenses on the one hand, and on the other toward lenses of short focus and wide angle. The telephoto lenses used for spotting would be of long equivalent focus—a meter and more—but of handy size, that is, not more than 50 centimeters over all working distance. The wide angle short focus lenses would be designed for low flying reconnaissance or quick mapping work. They would also be demanded for peace-time mapping projects, where the largest possible amount of territory should be covered in a single flight. Both types of lens should be pushed to the extreme in aperture, for short exposures and the maximum of working days will always be demanded.

Cameras.—Peace-times will give the necessary opportunity to develop self-contained and therefore simply installed cameras. They will at the same time be made very completely automatic but simple to operate in spite of their complexity. Such cameras have, during the war, been the ideal of all aerial photographers, but the time has been too short since the necessary conditions have been understood for that lengthy development work and those complete service tests which are so necessary to develop all automatic apparatus. Several designs which are now being perfected may be counted on to take us a long way toward this ideal.

On the other hand, that military ideal which leaves the camera operator the greatest possible freedom for other activities, is apt to be entirely reversed in peace. The camera operator can now be required to be an expert, who will be free to change plates or filters and to estimate exposures, instead of giving his best efforts to the problem of defence. For him a simple and reliable hand-operated or semi-automatic camera is entirely satisfactory, and the great expense of complicated automatic apparatus has no longer its former justification.

Camera Suspension.—Perhaps the most pleasing prospect before the aerial photographer as he turns from war to peace work is that of having planes built for and dedicated primarily to photography. Instead of his camera being relegated to an inaccessible position, picked after the plane design has been officially “locked;” instead of yielding first place to controls, machine gun and ammunition; instead of being jealously criticised for the space and weight it takes up, the camera can now claim space, weight, and location suitable for any likely aerial photographic need. High speed no longer will be vital, and slower planes, permitting longer exposures in inverse ratio to their speed, will be chosen for photographic purposes.

A development which is sure to intrigue many investigators is the gyroscopically controlled camera. This has its chief raison d'Être in precision mapping, whose possibilities from the air will undoubtedly be intensively studied at once. With the automatically leveled camera will come renewed attention to indicators of time, altitude, and direction, with the ultimate goal of producing aerial negatives that show upon their face the exact printing and arranging directions necessary to put together an accurate map.

Sensitive Materials.—Manufacturers of plates and films will direct efforts toward producing emulsions of good contrast, high color sensitiveness and high effective speed, especially when used in conjunction with the filters necessary for haze penetration. Exposure data will be accumulated and exposure meters appropriate for aerial work will be developed.

Color Photography.—Color photography from the air by any of the screen-plate or film-pack methods is probably out of the question because of the long exposures required. The screen-plates are unsuitable also because of the relatively large size of their grain compared to the detail of the aerial photograph. Ordinary three-color photography, using three separate negatives, is always subject on the earth's surface to the difficulty that the three negatives must be exposed from the same point of view, either in succession or by means of some optical arrangement which is costly from the standpoint of light. In photographing from the air this difficulty of securing a single point of view for the three photographs is absent. Three matched cameras, side by side in the fuselage, have identical points of view as far as objects on the earth below are in question. Consequently, three-color negatives are entirely possible, and indeed will be simple to make as soon as plates of adequate color sensitiveness and speed are available. Probably the new Ilford panchromatic plate has the necessary qualities.

Night Photography.—The searching eye of photography was so omnipresent in the later stages of the Great War that extensive troop movements and other preparations had to be carried out either in photographically impossible weather or else at night. The natural reply to the utilization of the cover of night is to “turn night into day” by proper artificial illumination. At first thought it might well appear that the task of illuminating a whole landscape adequately for airplane photography is well-nigh hopeless by any artificial means. On one hand we have the very short exposures alone permissible; on the other the fact that the intensity of daylight illumination is overwhelmingly greater than those common in the most extravagant forms of artificial illumination.

Toward the close of the war, however, actual experiments made with instantaneous flashes of several million candlepower showed that if proper means were provided to insure the flash going off near the ground, and if its duration were made no longer than about 1
50 second, interpretable photographs were obtainable on the fastest plates. It appears, therefore, merely a matter of manufacturers perfecting the technique of flash production, and of inventors providing the launching and igniting devices to push this kind of photography to the practical stage. The achievement of night photography cannot fail to have an enormous effect on future tactics.

The technique of night photography may take either of two directions. On one hand we may develop flashes of the requisite intensity to give all their light in 1
100 second; on the other hand, it may prove more feasible to use flashes of longer duration and to arrange for the camera shutter (of the between-the-lens type) to be exposed synchronously with the middle of the flash. One way, frequently suggested, to use these longer flashes would be to trail the charge on a long wire, through which the ignition is effected electrically. This is not likely to be satisfactory, however, for the resistance of a wire is so great that when the plane flies at any practical height, the trailed flash, if it reaches near the ground, will be forced to a very great distance behind. Probably the best solution will involve accurate synchronizing of the fuse in the freely dropped sack of flash powder with the exposing mechanism in the camera.

Aside from their element of novelty, aerial photographs have undoubted qualities of beauty and utility. The “bird's-eye view” has always been a favorite for revealing to the best advantage the entire form and location of buildings and of other large objects. Heretofore such views have usually had to be drawn by an imaginative artist.

Aerial oblique views possess the virtues both of pictures and of plans. They are destined to be extensively used in the study of architecture (Fig. 188). Cathedrals, castles, town halls, particularly those still in their cramped medieval surroundings where they can never be seen in their entirety from the ground, come forth in all their beautiful or quaint proportions from the airman's point of vantage. Stereoscopic aerial views are destined to occupy a valuable position also. Stereo prints of the famous buildings of Europe, taken from the air, will give to the prospective traveler or the arm-chair tourist a many fold more accurate idea of their construction than will any number of mere surface views.

A vertical aerial photograph is most closely akin to a map, but has advantages over any ordinary surveyor's product. As a guide it is infinitely superior to the best draftsman's diagram, for it provides a wealth of detail whereby the traveller may definitely locate himself. At a single glance he notes the objects of interest within his radius of easy travel. The guide-book of the future will therefore be incomplete without numerous aerial views, both vertical and oblique. As an illustration of the peculiar merit of the view from the air, consider the photograph of Vienna made during d'Annunzio's “propaganda” bombardment. Or the picture of the Rialto bridge (Fig. 190). No ordinary photograph from land or water suggests the central roadway and no map shows the beauty of its elevation. Both are shown here, as well as an intimate view of the arched and pillared courtyard of the Fondaco de' Tedeschi to the right.

Airplane photographs will undoubtedly be widely used in certain fields of advertising. Architects and real estate agents may be expected to display their wares by the aid of aerial views. A well-planned country estate or golf course, or a suburban development (Fig. 191), can be shown with a completeness, both as to environment and stage of progress which no other form of representation can approach. A sea-side resort can now show the extent and grouping of its natural and artificial amusement features in a single picture (Fig. 192). Even the extent of its bathing beach under water is revealed to the aerial photographer (Fig. 193). Real estate agents can utilize aerial photographic maps of cities to great advantage. On these their properties can be pointed out, with the nature of their surroundings shown at a glance, together with their relation to transportation, schools, churches, shopping districts, parks, or factories. The future purchaser of lots in a distant boom town will no longer be satisfied with a map outlining the streets with high-sounding names. He will demand an authentic aerial photograph, showing the actual number of houses under construction, the streets, gutters and sidewalks already laid, the size and planting of trees.

The study of landscape gardening is another field for which the aerial photograph is peculiarly fitted. A collection of oblique pictures of the chÂteaux and palaces of Europe showing their approaches and grounds, or of the historic estates of our own South, (Fig. 194), will be worth more to the prospective designer of a country estate than maps and ground pictures can ever be. Closely allied to landscape gardening is city planning, for which the aerial map will be quite indispensable. The appearance of a city from the air may indeed become a matter of pride to its inhabitants, and not only the arrangement of streets and parks, but even the character of the roofs of the buildings, be the subject of study (Fig. 195).

Engineers and constructors will depend more and more on preliminary photographic surveys as a basis for locating their operations. At the later stages of their work they will use aerial photographs for recording progress. Periodic photographs of buildings in process of construction, such as are now made from the ground, are much more illustrative when made from the air. Only from above is it possible to obtain in a single picture the progress of the complete project, such as the construction of an aviation field (Figs. 196 and 197) or of a shipyard. The building of large structures—bridges, hotels, ships on the stocks—particularly demands aerial views if the foreground is not to eclipse the center of real interest.

News events will soon call for an aerial photographic service. Already we are seeing newspapers and magazines featuring aerial photographs of the entry into conquered cities and the parades of returning fleets. Accidents, fires, floods and wrecks, of either local or national interest, can best be represented by this newest form of photography.

The photographing of wrecks, fires and floods suggests the importance of aerial views to insurance underwriters, who require the most minute information on the characteristics of buildings in every neighborhood, and on the extent and nature of damage done. Marine insurance companies might with profit use the airplane camera to help estimate the chances of salvage of a stranded ship or a vessel foundered in shallow waters (Fig. 181).

Numerous scientific uses for aerial views seem likely. Prominent among these is their use in geology, for the study of the various forms of earth sculpture. Pictures from the air of extinct volcanoes will give information as to their configuration that would otherwise require months of painstaking survey to obtain. Aerial photographs of active volcanoes (Fig. 198), showing the results of a succession of outbursts—one obliterating the other—would prove of the greatest value, especially when studied in conjunction with other scientific data, the whole making a record unobtainable by any other means.

In earthquake regions—notably Southern Italy and Japan—the changing coast lines, shallows and safe harbors, could be promptly ascertained after the subsidence of each fresh shock, with a consequent keeping open of trade routes and often the saving of life. River courses, glacier formations, caÑons, and all the larger natural formations which man usually sees only in minute sections, and which he must build up in his mind's eye or by models, are today quickly and accurately recorded by the camera in the air. Such formations as coral reefs, whose configurations can now be accurately learned only by laborious surveys of a limited number, could be studied in quantity and with heretofore unknown satisfaction as the result of a single expedition with a ship-carrying seaplane and aerial camera.

Another scientific field—probably one of many similar ones—lies in the study of the waves set up by ships (Fig. 199). These are of extreme importance in the realm of naval architecture, but before the day of the airplane could never be easily studied in full scale.

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).

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.

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.

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!