PHYSIOLOGICAL ASPECTS OF FLYING 205 



in the subject under examination these are satisfactory 

 or not can be assessed. 



It has also been found that in good pilots the pres- 

 sure maintained within the circulatory system between 

 the beats of the heart (known as the diastolic pressure) 

 is relatively high, and that the difference between this 

 pressure and the pressure when the heart is beating 

 (the systolic pressure) is not more than 30 to 40 milli- 

 metres of mercury. The difference between these 

 pressures should not be too great, and the diastolic 

 pressure should certainly not be low in any subject 

 passed for aviation. 



It will be seen that in the examination of the candi- 

 date considerable reliance is placed upon instrumental 

 examination. Such examination gives definite results, 

 which can be recorded so that another medical officer 

 at a subsequent stage in the career of the candidate 

 can contrast the condition of the subject then found 

 with that found previously. In this way the medical 

 officer of an aerodrome is able to overhaul the human 

 engines under his charge, and to say whether they 

 are functioning well, wearing well, or showing signs 

 of stress, and, if the last, to take appropriate measures 

 to prevent it. For this reason, all such tests should 

 be of the simplest possible nature. 



In addition to wearing well, that is, in addition to 

 being sound in wind and heart, other qualities are 

 necessary for the pilot to become a successful aviator. 

 Most important of all, he should possess the flying 

 temperament. This, however, is very difficult to assess 

 from a medical point of view. 



Generally speaking, one prefers a man possessing 

 what may be termed the " sporting temperament". 

 The successful flier is practically always a sportsman. 

 He generally takes up flying because he looks upon 

 it as a sport. His previous record in games is in- 



