Page:Popular Science Monthly Volume 91.djvu/730

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��Popular Science Monthly

��no latent tendency to turn up or down, in or out. The test is important. If there were any such latent tendency, it would manifest itself under great strain ; the aviator would see double and thus en- danger his life.

And now the ear, nose and throat are examined. The hearing must be per- fect; there must be neither diseased ton- sils nor adenoids ; both sides of the nose must be free, which means that there must be noth- ing present to pre- vent the automatic equalization of air pressure through the Eustachian tubes (the little tubes lead- ing into the middle ear). A military aviator is subjected to a wide range of variation in temper- ature and atmos- pheric pressure. If his nose and throat are not normally ventilated these rapid changes might produce dizziness, vertigo and nausea. He might not be able to control his machine, with the result that he would wreck it and lose his life.

Your Sense of Balance Is in Your Ears

We have been taught that we have five senses — sight, hearing, touch, taste and smell. A sixth should be added — that of equilibrium. It is as much a separate sense as touch or sight, and that it is en- titled to consideration as such, the develop- ment of aviation is fast driving home. Balance, or equilibrium, is maintained through the eyes, the skin, the joints and muscles, and, much as it may surprise you, the ears. Just as the end organ of sight is in the eye and the end organ of feeling in the fingers, so the end organ of equilib- rium is to be found in the ears.

As the accompanying diagram shows, the inner ear is made up of two parts — a cochlea, which contains the end organ of hearing, and the labyrinth, which contains the end organ of balance. In other words, the labyrinth of the ear is the human stabilizer. Nevertheless, from the time

���How Long Did It Take Him to Recover?

After having been revolved with eyes closed in the chair, the applicant is told to look at a distant object. There will be a rhythmic to and fro movement of the eyes. It lasts as long as the fluid within a particu- lar canal in the ear continues to flow artificially

��that man first discovered the possibilities of travel over the waters and hoisted his first sail over a log, down to the time when he navigated great ocean liners, this little organ of bal- ance has been the one thing that has made the sailing of the seas unpleasant. Not the stomach or liver, but the lab- yrinth is the cause of seasickness. Is it not singular that the organ which upsets us on the ocean sta- bilizes us in the air ? Were it not for the constant intelligence flashed by the lab- yrinth to the brain, the aviator might actually find him- self soaring upside down! His move- ments in the air up and down, right and left, in and out, are constantly regis- tered by this won- of mechanism within

��derful little piece

���The Test for Pass-Pointing

The applicant extends his right arm and touches the examiner's hand. Then he raises his arm vertically and is told to bring his finger back and touch the ex- aminer's hand again. Another picture shows the result

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