Popular Science Monthly
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���Can He Pilot a Battleplane i
To find out if his sense of balance is good he is whirled around in a special chair. The object of the whirling is to displace the fluid in the labyrinth of the ear, the fluid that controls your sense of balance and tells you whether you are standing on your feet or your head. The examiners then note how long it takes him to recover poise
��it and to select, by punching through the perforations, anything in the chart which appears red or green, as the case may be. These punches are recorded on a blank beneath the chart, so arranged as to show
��whether or not the selections were correct. The eyes must be in perfect alinement. To determine whether they are or not, their muscle-balance, as it is called, is taken. In other words, they must show
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