AND IN THE TROPICS, TOO

The station records of the Army and Navy Air Services reveal interesting excursions into the little-known territory of our island. possessions. Near Central America, for example, there are thousands of islands which depend upon shallow-draft sail boats for communication. Trips require many days and but little intensive exploration had been done. The all-seeing eye of the aerial camera has been turned upon these regions and as a result geographies are being improved.

If continental United States is inadequately mapped, what of Hawaii and the Philippines? Flights are constantly being made in the islands by our Service planes and full utilization of the scientific results of these tours awaits only more adequate co-ordination of our aerial activities in Washington.

LOCATING A RAILROAD BY AIR

The Air Service, which is keen to aid commercial aeronautics in every way possible, reports the following concerning the locating of a railroad in the Philippines by means of aircraft:

"Locating a railroad by airplane is the latest venture of the Third Aero Squadron, Camp Stotsenburg, Philippine Islands, and one long flight has enabled a railroad engineer to determine which one of three general routes will be utilized for the new road. The saving of many months and thousands of dollars has resulted. Instead of three parties of locating engineers being sent out to make the preliminary survey only one will now be necessary. "The Manila Railroad Company has planned the extension of its line from Cabanatuan through parts of the provinces of Nueva Ecija and Nueva Vizcaya to Bayombong. Parts of the two provinces are very thinly settled and no comprehensive maps or surveys were available.

"The military authorities are vitally interested in the extension of the Manila Railroad Company line, and accordingly permission was obtained from the Commanding General, Philippine Department, to use a government airplane on the preliminary reconnaissance trips.

“The first trip was made by Mr. E. S. Von Piontkowski, Chief Engineer, in a D. H.-4 piloted by Lieut. W. C. Maxwell, 3rd Aero Squadron. Lieut. Maxwell, with the railroad officials in the gunner's cockpit, passed over Mt. Arayet and then followed the Pampanga River until he picked up the railroad line at Gapan. He followed the river from Cabanatuan on to Pantabangan and over Mt. Pangloriahan, thence to Bayombong.

“The railroad engineer on the return was enthusiastic over the trip, declaring that the single flight has saved him months of tedious work in running lines through difficult territory. Before his surveying party is sent he plans at least one additional reconnaissance trip."

AIRCRAFT IN URBAN DEVELOPMENT

It is many leagues from Philippine engineering to transportation problems in the heart of New York City or Chicago. Yet aircraft provide a common utility.

City planners who have long drummed into the unheeding ears of the American public the wisdom of starting new cities aright and remedying the old by applying a little wisdom in the disposal of terminals, municipal buildings, residential districts, sanitation facilities, etc., have found in aircraft a propagandist as well as a powerful

servant.

"There would be fewer opponents of city planning, could they see the average city as it actually is from the cockpit of an airplane," says a writer in the American City Magazine. "A view of a city from above gives to the city planner its appearance as a whole. Some men have the rare gift of visualization and can construct the picture from a knowledge of its parts. The successful city planner must accomplish this by some means or other, because in the broad sense city planning disregards concentration or details and concerns itself primarily with the formation of the complete entity. The airplane does not give that confusion of detail one is so apt to get on the ground, and the general plan stands sharply out. Maps and drawings cannot give just this result because they cannot adequately differentiate the old buildings from the new, or, indeed, show anything except in a conventional and mechanical manner.

"When a city-planning scheme is decided upon, it is rare that there are suitable plans or maps to guide one. Plans, as a rule, are littered with streets projected, subdivisions proposed, buildings and improvements not existing on the ground. Everything that the map shows has to be verified before planning work can begin. Aerial photography avoids this by the production of a pictorial survey accurate to the very minute the picture is taken. The city planner making a flight over a city can correct his maps in the air, mark the limits of the built-up area, etc., and altogether form a fairly good estimate of the correctness of the maps.

"From the air, the value of space, fresh air and light are realized much more than on the ground, where one is too near the picture to comprehend it properly. And, again, parks, open spaces and trees are seen as distinguishing landmarks. Buildings seen in bulk suggest questions at once-open space? residences? adequate roads? factory locations? and so on. One strives to reconcile all these features in the scheme of things. No amount of map study could place them in the same relationship one with the other and with the city as a whole."

If not "town planning," then "town correction." Here, too, is where the aerial photographer is making good. The Fairchild Aerial Camera Corporation, to which the compilers of this volume are indebted for much information, states:

"We recently took a series of views of the congested areas of New York to show for the American Red Cross the block after block of tenement buildings with no parks or playgrounds. A hundred ground pictures would not record what this one aerial view showed.

"Real estate is most advantageously shown by the aerial view. The New York Evening Post is one of the pioneers in this movement. Every Saturday the real estate section of the New York Evening Post contains an aerial view of some new real estate development. Many engineering firms have had aerial views taken of properties. Insurance companies examining risks have found the aerial mosaic of great value in revealing the character and type of buildings, together with their surroundings."

THE TECHNIQUE OF AERIAL PHOTOGRAPHY

Preceding sections of this chapter may have raised a question in the mind of the reader just how aerial photographs are made and applied, not only to scientific but commercial problems.

Major H. K. Maxwell, formerly in charge of photographic training of the British Royal Air Force, and who since the war has been engaged in commercial aerial photography, has contributed his views:

ver

"There are two distinct branches to this fascinating work tical photographs taken directly above the object and oblique views taken sidewise, the latter called bird's-eye views." He writes: 'Vertical photographs have been made of river and canal systems, harbor works and ports, oil fields, ranches and farms, town sites, railways, roads, streef car lines, plants, factories, etc.

"Rivers were depicted so that the currents, rocks, depths (in shallow water), condition of the banks, trees, course and surrounding country were plainly discerned. The constantly changing terrain. in the oil fields and all approaches have been successfully mapped by the aerial camera. Mosaics of ranch lands have been made portraying grazing and cultivated areas, fences, dams, irrigation, timber, nature of the terrain whether hilly or flat, condition of roads and trails and, in fact, everything that would require weeks by the old system. Yet the airplane photographer does it in a few hours.

"Scale maps of cities involve many problems, because of the varying height of buildings and the multiplicity of streets which must be photographed at certain set times owing to shadows and difficulty in eliminating an accumulated error over long lines of streets and avenues. Large cities are at present difficult to map in this manner, although it is only a matter of time and experience.

Cities 25 square miles in area have been mapped accurately, every possible detail being shown, even trees and shrubbery in the gardens.

MAKING VERTICAL PHOTOGRAPHS

"Three methods of making vertical photographs are, first, matching and joining the photographs, by which the mosaic is correct, but the scale may not be; second, carrying out a preliminary survey by triangulation so that definite, marked points will appear in each photograph and then making the mosaic from known measurements between these points; third, building up a mosaic from actual survey data of the terrain.

"The second and third methods cost three or four times as much as the first and, though they are suggested for accurate work, the first will prove satisfactory if care is taken, sometimes scaling to 1/50th inch error, which compares favorably with a majority of maps.

"It is almost impossible to make a map or mosaic from aerial photographs without a suspended camera, either controlled by hand or gyroscopically - and the latter at present cannot be practically carried out; a plane which not only gives a clear and uninterrupted view to the pilot (especially) and photographer but has a high speed and a ceiling of at least 16,000 ft. which it can reach fully loaded in at least 30 minutes and maintain for at least three hours; a pilot who is not only a perfect flier, but can accurately fly a series of straight lines over country which has few if any prominent land marks, with a perfect and concise knowledge of map reading and cross country flying generally, and a certain amount of photographic knowledge; an aerial photographer with a steady hand and an absolute mastery of his camera under all conditions, a trained reader of maps, and all sorts of country and a clear and concise knowledge of his object; a skilled surveying or civil engineer to arrange the scale and method of procedure and put resulting photographs into accurate map form. There is also required a skilled darkroom. staff, probably the most important of which is the printer; for aerial negatives are nearly always a little uneven and if this is not corrected in the printing room, a resulting mosaic will look like a patchwork quilt rather than an evenly colored picture of the terrain.

MAKING OBLIQUE PHOTOGRAPHS

"There are many ways of making oblique photographs of scenery, real estate and properties, but there is only one way in which this sort of subject can be fully depicted and that is by flying around it at heights and over certain points which have been decided before

hand and on knowing which, photographs can be obtained, giving any angle of view required. In this way the resulting photos show the extent, size, position, height, shape, and every detail of the buildings and grounds concerned in a way which is so much better seen and easily comprehended, that a photo taken from the ground can show no comparison.

"All governments are interested in this work, but the U. S. Army Air Service, without doubt, has accomplished more and progressed further in solving the many intricate problems than the others, especially in the survey and mapping division; while its oblique work with the long focus lens will remain for some time the best that has been produced."