The Wrangell sentinel., 1926-08-12

most ambitious man. When one checks the amount of territory to he covered by this survey it will be seen to be by far the largest in square miles yet attempted by the air service of any nation. From q standpoint of the ruggedness of the terrain surveyed. it has no equal.
 There is little of general interest in the technical details of aerial pho tographing butt in the results ob- tained in Alaska it has intense in terest, not only in Alaska, but in the | United States and especially at Washington. D. C. During but a few weeks of actual flying in South eastern Alaska by the naval forces engaged in this work much has been learned of the actual possibilities for future development in this sec tion of the country.
 By the usual method of surveying the plane table is used and the country has to be laboriously trav- ersed on foot-an almost impossible task in the dense brush and timber ed mountains of Alaska. By the aerial method, the flyer takes his film and camera aloft, flies over the territory, takes photographs, deyel- ops them, and then matches adjacent prints into a complete mosaic pie true which shows the entire terri tory under survey. It is possible to scale this picture as accurately as any chart, or for that matter a blue print. In this map all details such as trails, trees, streams, mountains, cultivated and uncultiyated land are clearly seen. In short an aerial survey is a picture which. places all objects in their exact position and size in relation to one another.
 The rapidity with which an aerial survey can be made is astounding A plane flying at 15,000 feet above sea level making one hundred miles per hour can survey a strip seven miles wide and one hundred miles long, that is, seven hundred square miles, in one hour. Imagine the man on the ground covering seven hundred square miles of mountain territory in one hour.
 The camera is mounted in the bottom of the plane and kept in the vertical position so that the pho<o- graphs are taken looking straight downward. A roll of film is used which is six inches in width and three hundred eighty feet in length containing one hundred ninety expo sures. The exposures are so timed that the objects on the ground over lap on the print about forty per cent. In other worls aerial mapping is nothing but a moving picture re- yersed. The camera does the moving while the objects photographed are stationary.
 The area to be covered in the present survey is approximately forty thousand square miles. Due to the climate and the ruggedness of the country little progress has been made by the old methods of survey. Tn this region of so much stormy weather plane table methods are ex- tremely slow-since the mountains are much of the time covered with fog.
 The expedition comprises three units; the planes, the tender, and the barge. Of the three planes, two are used for mapping purposes, the third is always kept in readiness to search for any plane that might fail to return on schedule time. This plane, known as the re- lief plane, is equipped with radio and when in the air is in constant communication with the tender The Gannet is kept in readiness at all times during mapping operations to go to the assistance of any plane which may have been forced down by motor trouble or any other cause. During flight operations over particularly dangerous areas the Gannet is used as a patrol fitted with a motor shop for care Of the
 nlane motors, a special photographic
 laboratory where the film is devel
 oped immediately upon the return oi the planes from mapping, and radle equipment for communication WILT
 the planes or tender when they arc away from the base.
 In making the survey the flyers
 are seeing much territory seldom
 before viewed by man. Lakes have
 been discovered on the island of Re
 villigegido that eventually will pro
 duce tremendous power to turn th'
 wheels of industry. From many O the lakes never before charted, vii come the power to make pulp ant
 paper thereby utilizing one of tn greatest natural resources or south eastern Alaska. Many bright days and favorabl atmospheric conditions have aide'