DISCOVERY 



173 



carrying out survey work in countries where natural 

 conditions make ground survey difficult, if not 

 impossible. 



One of the most interesting cases in which aerial 

 photography lias been used was in the dispute some 

 little while ago between the municipal authorities of 

 Edinburgh and Leith with regard to the boundary 

 between these two places. When affairs had reached 

 a high legal state, it was found necessary to obtain a 

 map of the boundary as no up-to-date map was 

 available. In order to secure the requisite information 

 in the shortest time and with the least expense, an 

 aeroplane was sent up and in the course of one flight 

 secured a series of photographs which were enlarged 

 and pieced together, showing clearly the whole of the 

 disputed area. 



After the Armistice all the big towns in Egj-pt \\'ere 

 accurately surveyed from aircraft. In India, Canada, 

 and the United States aircraft have been used to 

 photograph the timber areas, and from the shading, 

 the type of timber which grows in these areas. For 

 medical purposes aerial photography has been emploj'ed 

 in order to locate mosquito-breeding swamps. 



One of the latest applications of aerial photography 



has been in \'enezuela, where aircraft have been 

 i,mployed to take photographs in the Orinoco Delta 

 in order that the grourid might be surveyed for oil- 

 bearing districts. This country is practically im- 

 possible to negotiate on foot, but it w*as found that 

 aircraft could make use of the waterways and photo- 

 graph the surrounding country, the oil-bearing areas 

 showing up clearly as bare regions in the surrounding 

 vegetation, for oil kills all trees and shrubs in its 

 neighbourhood. 



At the present time one of the greatest needs for 

 aerial navigators is the production of suitable and 

 reliable air maps. Such maps must be accurate and 

 should show the ground to be flown over in such a 

 manner that it should be easily recognisable by the 

 pilot of a machine. Existing maps are, in many cases, 

 ijuite useless, and it is probable that the best form of 

 map will be that prepared entirely from aerial photo- 

 graphs of the routes flown over. These will need 

 certain points emphasising in order that the pilot may 

 compare the ground and map with as little difficulty 

 as possible, but, generally speaking, the aerial photo- 

 graph will be sufficient in itself to prove a reliable 

 guide for travellers in aircraft. 



FIG. ;.— THE GRE.^T I'\K.i.m;i.- i -M AX AIZRuP:, AM. 



The wireless station on the top of Cheops s Pyramid is seen at the bottom of the picture 



