432 



SCIENCE 



[N. S. Vol. XLIX. No. 1271 



of, attack, can swoop down upon him from 

 above. 



Witli this as one of the fundamental con- 

 ditions of aerial warfare, it was inevitable 

 that in the development of the battle plane 

 there should be the utmost effort to pro- 

 duce machines of continually greater speed 

 and, its correlative, climbing power. Like- 

 wise in the air, the greatest practicable alti- 

 tude has meant for the flying man at once 

 an advantage over his enemy and a re- 

 d^uction of his own chance of being hit by 

 anti-aircraft fire from the enemy's guns 

 on the ground. 



Accordingly, from the comiparatively low 

 altitude at which the aerial fighting of the 

 first year of the war usually occurred, the 

 struggle rose, as more and more powerful 

 aiiiplanes were 'Constructed by both sides, 

 until at the end of the war it was quite 

 common for battle planes to ascend to alti- 

 tudes of 15,000 to 18,000 feet— three miles 

 up, higher than the summits of the Rocky 

 Mountains or the Alps. 



Along with this development there oc- 

 curred with increasing frequency among 

 the aviators a condition of so-ealled "air- 

 staleness." It is a condition closely sim- 

 ilar to, perhaps identical with, the "over- 

 training" or staleness, the physical and 

 nervous impairment of athletes in a foot- 

 ball team or college crew. In the last year 

 of the war this condition had become so 

 oommon that, as reported to us by some ob- 

 servers, the majority of the more experi- 

 enced aviators in the British service were 

 incapacitated to ascend to the necessary 

 altitude, and many could no longer fly at 

 all. It was to make good this most serious 

 military deficiency that the enlistment and 

 training of aviators was undertaken by the 

 American Air Service on the enormous 

 scale that it was. It was for the purpose 

 of testing our airmen initially, and of keep- 

 ing tab on their physical condition there- 



after, that the work at the Mineola lab- 

 oratory, of which probably you have heard, 

 Avas undertaken. 



It is work which lies in a field of phys- 

 iology in •wliioh before the war not half a 

 dozen men in America, and not many more 

 in Europe, were interested, and for them it 

 was a field of what is called "pure" sci- 

 ence. To-day it promises contributions of 

 practical value not only to aviation, but to 

 prolblems in medicine, climatology, ath- 

 letics and hygiene. 



We will turn then to the problem of the 

 aviator and the methods of human engi- 

 neering which have been developed for its 

 solution. But first, it wiU be advisable to 

 review briefly what is known concerning 

 the immediate effects of low barometric 

 pressure and the functional readjustments 

 involved in acclimatization to elevated re- 

 gions ; that is, life at great altitudes. 



Paul Bert,- the brilliant French physiol- 

 ogist, was the first to demonstrate, in 1878, 

 that the effects of lowered barometric pres- 

 sure or altitude are whoUy dependent on 

 the decreased pressure of oxygen. He 

 carried out experiments upon men and 

 animals both with artificial gas mixtures 

 and reduced barometric pressure in a steel 

 chamber. 



He showed that in pure oxygen at 21 per 

 cent, of atmospheric pressure life goes on 

 in practically the same manner as in air, 

 which contains 21 per cent, of oxygen, at 

 the ordinary pressure. So also the breath- 

 ing of an artificial gas mixture containing 

 only 10.5 per cent, of oxygen has tlie same 

 untoward effects at sea level tliat breath- 

 ing pure air has at an altitude of about 

 20,000 feet, where the barometer is reduced 

 by one half. 



These considerations are fundamental 

 for the differentiation of the disorders in- 



2 Paul Bert, "La Pression Barometrique, " Paris, 

 1878. 



