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Aviation History
1941
1941 - 2433.PDF
OCTOBER I6TH, 1941. FLIGHT AIR SURVEY WORK Extensive Use of Aircraft in India MOST of the world has beenmapped, but only a small pro-portion of it has been sur- veyed. Air survey is very gradually, but also very surely, gaining accept- ance as a method of great efficiency, and India is one of the countries where extensive use has been made of it. Operations have extended from Burma to Baluchistan. In the east surveys have been made from bases at Chittagong, Akyab and Dacca, while in the west the work was carried on from Quetta and Karachi. Surveys were made for geological research, town-planning, harbour development, irrigation, river control and power line development. In the air survey laboratories and the mapping office at Dum Dum photographic plans were completed of the town of Ujjain on a scale of 32 inches to one mile, plans were drawn for the various surveys above-mentioned and several sets of photographic prints covering over 12,000 square miles of territory were made for stereoscopic examination. One hundred and nine square miles of maps on a scale of 8 inches to one mile and 100 square miles on a scale of 4 inches to one mile were turned out by the topographical mapping section. The science of air survey is developing in India with notable success. More than 83,000 square miles in India and Burma have been surveyed since operations began in 1924. For the revision of large-scale agricultural and town maps, the planning of public works, the prevention of flood, for oil and mineral prospecting—to name but a few of its many applications—the work of the air surveyor is saving both time and money- Harbours, Rivers and Geology Forestry and delta surveys first engaged the air surveyors' Ettentions because of the excessive cost of surveying such difficult terrain by normal means. The second step forward was the revision of large scale maps of agricultural districts, and town surveys were undertaken later. Prior to 1928 little air survey had been done. Pioneer- ing work was done in Burma, the Federated Malay States and Borneo in compiling early maps of forest areas, rivers, coast lines and deltas which 'vould have been practically impossible to map by surface means owing to cost. Ex- perience gained here was put to use in producing in 1927-28 as an experimental measure a map of Chittagong District of Bengal to the very large scale of 16 inches to the mile. Prior to that a scale of 6 inches to the mile had been con- sidered ambitious. But technique was not sufficiently developed at that stage for the satisfactory production of maps on so large a scale. This mud crater photographed in India is an instance of the value of the air camerain providing geological information which otherwise would be obtainable only after great expense and delay. In spite of initial disappointments work was continued, due largely to encouragement given by the Survey of India and the Bengal Government. New methods were de- veloped, and during the succeeding eight years four com- plete districts of Bengal and 4,000 square miles in the United Provinces were mapped from the air. Vertical photographs each overlapping its neighbour by 60 per cent, were found to be excellent for the revision of torn maps, such as those of Indore and Nagpur. Engineers responsible for harbour engineering and for devising protective measures against seasonal floods of rivers have found the information provided by air photo- graphy of very great assistance. Photographs of Karnafuli river taken under conditions of high and low water dis- closed the locality of banks beneath the surface by eddies or "tails" of silt in suspension. River photography shows up erosion and siltation by the condition of the banks, as well as by curvature and direction of flow. The cause of devastating floods which occur almost every year in Orissa has been shown by air photographs to be due to stoppage of the many outlets of rivers along the coast by silt and also by sea-washed sand. The deteriora- tion of cultivable lands in the Punjab through saline satura- tion was investigated experimentally by the air camera. It was found that, in winter, the surface salt shows white in the photograph, Yet another aspect of air photography is photo-geology, which is the best means available to the geologist for getting information rapidly. This entails the use of the stereoscope, which gives him the exact representation of the ground in relief. Stereoscopic photographs are taken into the field .and examined in this manner. After correlat- ing the geological data obtained on the ground, large tracts car. be geologically mapped in the office with rapidilv an accuracy of detail. Oil prospecting in Baluchistan v.as advanced by air photography when more than 1,000 square miles of land were surveyed. Important geological sur- veys have also been carried out in Bengal and Burma. Aircraft from U.S.A. A IRCRAFT, aero engines and equipment to the value of more than $284,000,000 (approximately/71,000,000)v 'as delivered to British air forces, in Britain and else- where, by American manufacturers during the first seven months of the present year, according to a statement by Colonel J. H. Jouett, president of America's Aeronautical Chamber of Commerce. Col. Jouett did not disclose the actual numbers of air- craft nor the proportion of the various categories, but it has been estimated that the total sum mentioned would cover the cost of more than 8,000 fighters or 2,000 bombers. At least three-quarters of the total, however, were combat aeroplanes as distinct from training types, and they repre- sent nearly double the number of aircraft we lost in defending this country throughout 1940.
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