208 BIOLOGICAL PROBLEMS 



the position of his machine in space from his sense 

 of vision, the feel of his joystick, the feel of his seat, 

 from the direction of the rush of the wind upon his 

 face and the singing of the wind through the wires 

 of his machine. 



A medical man who went up as a passenger in 

 an aeroplane, with his eyes bandaged and his ears 

 plugged so that he could not hear the varying notes 

 of the engine and thereby gather information as to 

 what was taking place, was unable after the first few 

 minutes to inform his pilot by telephone, with any 

 degree of accuracy, the position of the aeroplane. In 

 fact, he experienced the sensation that he was con- 

 stantly rising. 



This fact was also brought out to the writer in the 

 following manner: greatly occupied by an instrument 

 in the bottom of the fuselage, he suddenly cast his 

 glance out of the aeroplane and received the impres- 

 sion that he was looking at the side of an enormous 

 mountain. He quickly, however, appreciated the fact 

 that, in reality, the apparent mountain was the flat 

 earth below, and that he was in the middle of a steep 

 vertical turn without being aware of it. 



Good eyesight is of extreme importance for the air- 

 man in all branches of his work. In particular is 

 this so for the scouting pilot, and it is a point of 

 interest that it has been found that nearly all scouting 

 pilots are possessed of such acuity of vision ; it will 

 be of interest to determine how much of this was 

 acquired before flying scout machines, how much as 

 a result of the training necessary to fly and fight in 

 such machines. 



Good colour vision is also necessary for recognizing 

 signals, identifying troops, and judging the nature of 

 landing-grounds. Good night vision is requisite for 

 all pilots who fly by night, and it is now recognized 



