May 9, 1919] 



SCIENCE 



439 



With this inadequate sketch of present 

 scientific knowledge regarding life at great 

 altitudes as a background, we may turn to 

 the application of this knowledge to the 

 problems of human engineering in the avia- 

 tion ser%'ice of our army during the war. 

 In September, 1917, I was appointed chair- 

 man of the Jledical Research Board of the 

 Air Service and was asked to lay out a plan 

 for the development of a method of testing 

 the abilitj' of aviators to withstand altitude. 



You will readily guess the line along 

 which one would attack such a problem. It 

 consisted in the development of an appa- 

 ratus from which the man under test 

 breathes air of a progressively falling ten- 

 sion of oxygen. The particular form which 

 we use is called a rebreathing apparatus. 

 It consists of a steel tank holding about 100 

 liters of air, connected with a small spirom- 

 eter to record the breathing, and a cartridge 

 containing alkali to absorb the CO. which 

 the subject exliales. Breathing the air in 

 this apparatus through a mouthpiece and 

 rubber tubing the subject consumes the 

 oxygen which it contains, and thus pro- 

 duced for himself the progressively lower 

 and lower tensions of oxygen which are the 

 physiological equivalent of altitude. To 

 control and test the accuracy of the results 

 with the rebreathing apparatus we installed 

 in our laboratory at Mineola a steel cham- 

 ber, in which six or eight men together can 

 sit comfortably, and from which the air can 

 be exhausted by a power driven pump 

 down to any desired barometric pressure. 



Such apparatus was however only the be- 

 ginning. The practical problem was to de- 

 termine the functional changes — pulse rate, 

 arterial pressure, heart sounds, muscular 

 coordination and psychic condition occur- 

 ring in the good, the average and the poor 

 candidates for the air service, and then to 

 systematize and introduce these standards 



on a very large scale at the flying fields in 

 this country and in France. 



That this program was successfully car- 

 ried through, and was approaching comple- 

 tion when the armistice was signed, was due 

 chiefly on tlie scientific side to the brilliant 

 work of my colleagues Majors E. C. 

 Schneider, J. L. Whitney, Knight Dunlap 

 and Captain H. P. Pierce, and on the ad- 

 ministrative side to the splendid coopera- 

 tion of Colonel W. H. Wilmer and Lieuten- 

 ant Colonel E. G. Seibert. 



We have recently published a group of 

 papers," brief but fairly comprehensive in 

 their technical details, and I shall not now 

 repeat what has there been said, but shall 

 confine mj-self to a few salient points. One 

 of these is a final and striking demonstra- 

 tion of our main thesis. Schneider and 

 Whitney went into the steel chamber and 

 the air was pumped out of it until the 

 barometer stood at only 180 mm., 23 per 

 cent, of the pressure outside : the equiva- 

 lent of an altitude of 35,000 feet. Through- 

 out the test they were supplied with oxygen 

 from a cylinder through tubes and mouth- 

 pieces. They experienced no discomfort 

 except from flatus: the gases of the stom- 

 ach and intestine of course expanded nearly 

 five fold. 



In comparison with this observation is 

 to be placed the recent record ascent by 

 Captain Lang and Lieutenant Blowes in 

 England to a height of 30,500 feet. They 

 were supplied with oxygen apparatus; but 

 a defect developed in the tube supplying 

 Lieutenant Blowes and he lost conscious- 

 ness. Captain Lang seems to have suffered 

 only from cold. 



From this it might appear that the 



Y. Hcn<lerson, E. G. Seibert, E. C. Schneider, 

 J. L. Whitney, K. Dunlap, W. H. Wilmer, C. 

 Bcrens, E. R. Lewis and S. Paton, Journal Ameri- 

 can Medical Associntion, 1918, Vol. 71, pp. 1382- 

 1400. 



