The Ear and Aviation.

In order to preserve the wonderful accuracy necessary in con trolling such a delicate mechanism as the flying machine, the avia tor relies preeminently on his ear balance-sense.It is highly probable that many an aviator has gone to his death because, all unknown to him, he did not possess a n,ormai ear mechanism.Even when an individual is standing or walking on the earth, his ears constitute his sense organs of balance; and he has in addition the contributory help of information received from his muscle sense and his sight.When he rises above the earth and flies in the dark it is obvious that these contributory factors are practically eliminated and that he must rely almost exclusively on the ear balance sense.The following briefly summarizes the fundamental principles underlying the examination for aviators.The aviator must have 20/20 vision without glasses.He must have 40/40 hearing.He must be a normal man, with the additional requirements of a cer tain relative height, weight, and chest measurement, and a definite vision and auditory acuity.Moreover, he must have a good bal ance-mechanism.The tests for nystagmus, pointing and falling1 are merely to deter mine whether or not the ear mechanism is normal.A limited num ber of candidates give what might be termed " border line " res ponses.It is here that the caloric test is useful.Water at 68° F. is allowed to run into the external auditory canal from a height of about 3 feet through a stop nozzle, with the head tilted 30 degrees forward, until the eyes are seen to jerk or the individual becomes dizzy.The length of time shown by the stop-watch in the normal i.Some Observations on the Barany Tests as Applied to Aviators, p. 563.