EXPLORATION BY AIRPLANE 



407 



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Fig. 3 



Fig. 4 



Fig. 3 — The echo sounding apparatus (Behm model) of the type used in making the sounding of 

 S440 meters in the deep basin of the Arctic Sea in latitude 77° 45' N. and longitude 175° W., on April 14, 

 1927, during the writer's flight to that point. 



The square objects to the left and right are batteries for the transmitter and receiver, respectively. 

 In the center is the head set, in the background are two coils of cable, on the sides two receiving mi- 

 crophones and in the center detonating cartridges. 



Fig. 4 — Riiser-Larsen making the sounding of 3750 meters in the Arctic Sea, May 28, 1925, 

 in latitude 87° 32' N. and longitude 10° 54' E., with an apparatus of the same model as shown in Fig. 3. 

 (Figs. 3 and 4 from Behm Echolot Gesellschaft.) 



daylight and continuous clear weather during certain seasons when the 

 sun is low and shadows are long bring about a condition ideal for 

 mapping from the air. 



For general observation close to a base an airplane ofifers the 

 advantage of being easy to handle on the ice by a limited personnel. 

 After landing, the plane can be anchored to the ice without difficulty, 

 turned in a small area, and moved in any direction. It will take off 

 and land in a small space, and it can be used for housing the party 

 during a long period of observation with less risk than with a ship 

 fast in the ice pack. 



The capacity of the airplane and the distance of the desired point 



