An exhaustive study of the ideal pilot established the fact that he should have an acute and correct sense of equilibrium. This does not appear so essential for an observer, who if he is fairly safe in the air and does not become giddy in stunting, may prove acceptable.
The “rotation tests,” described in detail below, have proved that as regards a great number of successful pilots—referring to those who have flown 100 hours and more,—in no case has a man been discovered who has not conformed to the above standards laid down for admission to the brigade. Above all there is demanded a sound physical condition, by which alone all bodily functions will respond normally.
The following data are taken verbatim from memoranda issued by the senior medical officer and authorized by the G.O.C. for the information of medical and flying officers:—
“For the information of the flying officer, a short explanation of the phenomena of equilibrium may not be out of place. Deep in the bones of the skull, in close connection with the hearing apparatus, lie, one set on each side, a series of three minute canals, filled with a clear fluid and lined with a membrane intimately connected by delicate nervous elements with the brain.
“These canals, each corresponding to half of the arc of a circle, are about half an inch in length, have a diameter of about one-twentieth of an inch and inter-communicate. They lie in the three dimensions or planes of space, and it is primarily due to movements in the contained fluid acting on the delicate nerve terminals, which are directly connected with the brain through fibres of the Vill nerve, that man is enabled to maintain the equilibrium of the body. It may be of interest to note at this point that the corresponding system in birds shows the extremely high degree of development one would expect. Knowing that to be a successful pilot a man must have an accurate and delicate perception of his position in relation to the earth, it is readily seen how intimately the internal ear, its adjuncts, and the problems involved in aeronautics are related. It should be understood that the canals mentioned above have nothing to do with the sense of hearing.
“Close to these, and in the same portion of the bone, lie two others closely resembling the spiral canals found in conch shells, and it is on these canals, also filled with fluid and lined with cells connected to the brain by fine nervous filaments, that we rely for our auditory impressions. It has been proved that not only dizziness, but also nausea and vomiting, all untoward symptoms frequently encountered in airmen, are closely connected with lesions or functional disturbances of the labyrinth of the auditory apparatus.
“In order to test the action of these canals, the contained fluid may be set in motion by rotating the body. This is most readily done by seating the patient in a revolving chair, and so, with the head in different planes, testing the different canals in turn. It has been found that pilots experiencing difficulty in flying, especially in maintaining equilibrium, and those who are troubled with vertigo or nausea, often show abnormal reactions, and it is for this reason that these tests are employed. These ‘rotation’ or ‘turning tests’ have been used for a considerable time in connection with diseases of the internal ear and in the diagnosis of lesions of the brain, but it is only recently, as a result of experimental work, that their application to aeronautics has been demonstrated and proved to be of practical value.
OPERATING ROOM. CAMP BORDEN HOSPITAL.