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Show f ' ' MAKING MAPS BY AIRPLANE Ey Froderic jr. Haskin. t : t WASHINGTON, May 4. To gather by photogTaphy all the materials for a map, Including tho elevations of hills and mountains, moun-tains, while flying over It in an airplane, will be possible within a few years, in the opinion of F. H. Moffit of the geological survey, who, toge-ihei with Major J. W. Bagley of the engineers oorps. and J. B. Mortie, also of the survey, has been at work for rrany months on the use of cameras r.nd airplanes for map-making. These scientists are developing a method of making accurate maps by photography from an airplane, of all features which show In the horizontal. That is, they can now make a map which will show the streams and lakes, the roads, railroads, forests and cities; but which will not yet show the elevations In any distinctive or reliable way. They have, however, among other devices with which they are experimenting, ex-perimenting, an instrument known as th.6 stereo-comparator, which makes it possible possi-ble to work out the elevations from two overlapping pictures U.ken from different points. While This method has .not been used except experimentally, it promises to be one mean? of solving the problem of topographic mapping from the air. ii is also possible to supplement the airplane map by a panoramic picture of the same piece of country, from which elevations may be obtained by a method which Major Bagley has perfected. The importance of this use of the camera and airplane in mapping can scarcely be exaggerated. To the government govern-ment alone it will be invaJuable. Tne gealogical survey, the coast and geodetic survey, the forest service and other branches of tlie government doi ng field work, spend thousands of dollars every year in making maps. Until a few years ago this entailed going into the country and laloriously mapping the topography of the plane-table method work requiring much time and fair weather. Major Bag-ley, Bag-ley, as a member of the geological survey, sur-vey, more than doubled the amount of work he could do in a season by the use of the panoramic camera. He had atill to go Into the country and scale the higi points, but the camera did in a second what would have required half a da. with a plane-table. The scientists had long seen the possibilities possi-bilities of the airplane for this work, but the instrument was not, before the war, sufficiently perfected lor their purpose. Now that the plane has become a stable and reliable craft, the inspiring possibility possi-bility opens up of mapping the wild mountain moun-tain regions of Alaska, for example, with detail and accuracy, while passing over them at tho rate of a hundred miles an hour. This will b3 as far removed from the method of the old-time photographer, toiling through the wiledrness with his load of instruments, as the automobile is from the ox-cart. War gave the Impulse which brought about this development in mapping methods. meth-ods. When things were at their worst in-Europe, in-Europe, and an invasion of America did not seem an impossible contingency,-Bag-ley and Moffit were impressed by the fact already realized by military authorities' that our Atlantic coastal country, from tho mouth of the Patomic clear' arounr1 to the Gulf of Mexico, was an unmapped country, much of it wilriesness. Wireless stations might have been (and possibly were) established in this country, while Its unknown creeks and bavous offered every possible advantago to an invading enemy. What was needed was a method of mapping this country with accuracy in a very short time. Theie was onlv one way of doing this from the air. Bagiev and Moffit brought their work to the attention of the council of national defense and received re-ceived an appropriation for carrying it on. letter the engineer corps, to which Major Bagley belonged, took up the method meth-od so that the work becamo a. co-operation between the geological survey and the corps of engineers. With these funds Bagley and Moffit built their aliplane cameras and their "rectifying" cameras, and carried on their experiments. A panoramic camera and tho ingenious Instruments bv. which he reduced his pictures to maps, had already been designed and constructed by Major Bagley. As a test of the apparatus. Genera'. iSlacK, chief of engineers, asked the two scientists to fly over the city of Washington Wash-ington and make a map of it. This they did producing by photography a map which compared favorably with one made on the ground. Tho general then asked them to cross another portion of tho citv In a ditlerent direction, and to Join the two maps This severe test was passed with notable success. These maps made 'by Baglev and Mof- t , .r XZl ,he f"'st """)S ma(le fro'" he an. The air service had been taking Pictures from f lai.es which were designed to reveal gun emplacements and the like and We,-e mHps , a somie. They hnc, ula rna-do mosaic maps" by taking a i-ioal many small pictures and putting them together as a child pieces out a Chinese Bagley and Moffit Improved this tedious tedi-ous method in two ways. In the first Place, they used a camera wit th e, lenses F.vuehronlzcd, ro that they could take a picture xvlth ,v very wide nimie One ler.s of this camera points It n ? t "le O,hor two- order o 'g ! dp-Xnt-nhrcturHi If you ever went to t. movies and mt know how the ro-,,, ": lcVu-- , ',,VOU ject.n, tho dior,cd'';ii, S 'pi tuoi'lto an inclined plane set. at an angle -would compensate for tha angle original exposure. If this explanation is not clear to vou, vou might visit the coming exhibition of the interior merit at which the Bagley-llofiil laments la-ments will be shown. ., Tlie chief source of error In t'l", map-making now is due to the : the nirplane cannot always be pljft; perfectly horizontal position. T ; . Is that even the central third oft; turo is distorted, and, like the u; Utres, must be corrected. M0'1. ( Lieutenant W. A. Hyde of the airs ; ( are now making experimental n;p-, a stabilized e-anura suspended tot-. ( plane and controlled by a gl'iosw', , gyroscope is operated by a sv... i and tends, of course, to keep tu ' , level, no matter what position UK. , takes. If tho scientists succeed ln, their earncra in a perfectly W; sition by tills method, they win , to make maps from the air wltn -. , , racy as gr'eat as most of those i- made uj on the ground. . i Most Ingenious of all the InftJ. , used in this work is the stereo-cji. lor. bv which elevations can M o--from hat pictures. This machine . vented bv a German for quite an-: pose, and is being experiment" -liagley and Moffit In their ; work. , The comparator finds clevatltn- -., , same wav that human eyes :l The only reason that you can - y, spectlve, or relief, in the lunoscaj f. . you is that you have two -,',,(! focus upon tho same thinf- ' -a .. 1 between thees- two lines of ah-' . r I by the brain, subconsciously, w fi Idea of the distance of the 5'i I at and of Its l elation to 1 ' (l i If you hud never had hut o m t . , would seo everything flat "u idea of perspective. , ii.. th1''' The stereo-comparator nppi. x -.! ciple, much as the familiar ,.-does, ,.-does, by placing two prints ' 1 " c, ( in sucti a wav that Vu lo ' . ,: each eye, through low-P-" n looking In this way at ' K: i' bouse, taken from an nlrr a - amazed to see that the nou.e f;,,i look like a tint blot, a Ppi" I seen bv the naked eyes. b!" v stand up from tro sroiina 1 should. So far you have om. (v- scope applied to pleiurf l1l.,;ii , alwvcv But till coiiM'.".'1'" ;. method by which you "J' ' '(n( i: J moving up and down a nK local plane of the eyeplc e, ' , K, dlstan e iren. top to bottoa ' 5 Thus. In the c-e of a ' ""r P-''1 you know one elevation i you call find them |
