590 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 3 8 



showed in a recent lecture on an Himalaya climb a photograph of a 

 lark sitting on her eggs at a height of 18,000 feet. And I suppose she 

 did not get there on her feet! 



The existing altitude record of 50,000 feet, obtained in 1936 by Flight 

 Lieutenant Swain in a Bristol airplane, was reached in a different way. 

 In this case the pilot was enclosed in a suit — rather like a diver's 

 suit — which could be kept at a pressure of several pounds per square 

 inch higher than that of the external atmosphere. Oxygen is pre- 

 ferred for such a suit because of the lower pressure required and hence 

 the greater ease of movement. Actually 2% pounds per square inch 



PROGRESS of WORLD S 



ALTITUDE RECORD. 



5 30.000 



(^ 20.000 



< 



1 I I I M ITTTM I I I m I I I m I i-i 



1905 



1910 



1915 1920 



Figure 3. 



I I I ■ I I IT 



1925 



1925 



1940 



is found to be a convenient pressure, and such a suit has been tested 

 in a low pressure chamber to a "height" of 80,000 feet. 



Of course, one may go further than a special suit and provide an 

 enclosed cabin in which a suitable internal pressure is artificially main- 

 tained. Although there would be grave objections to this in a military 

 aircraft, there would be none in civil machines other than perhaps a 

 reluctance to face the necessarily cramped space in which the occu- 

 pants would be confined. Although the temperature is low in the 

 stratosphere, flight at high speeds brings its compensation, since any 

 entering air would be heated by compression by the number of degrees 

 centigrade that is equal to the square of the speed in hundreds of miles 

 an hour, e. g., 9° centigrade at 300 miles per hour. 



