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Aviation History
1911
1911 - 0397.PDF
MAY 6, 1911. JySRT) AVIATION AND COMMON SENSE. IN the enthusiasm aroused by the recent sudden and wonderful developments in the line of aerial navigation, the aviators seem to have lost sight of certain principles of common sense, the observance of which would have protected them from many of the discomforts, dangers and tragedies of the past. As a consequence of this oversight it has been said that many of the most famous aviators, such as the Wright Brothers, Bleriot, Farman, Paulhan, Duray, Gibbs, Rougier, Sommer, &c, have been obliged to abandon the sport of flying because of accidents or because of the impairment of their health and nerves by ruined heart action, strained lungs, or attacks of vertigo and similar troubles in the air. As a result of experience it is suggested that the intense nervous strain of flying will, in a short time, so wreck the strongest nerves as to render a man unfit to go aloft under conditions requiring an absolute control of himself and instantaneous action in emergencies. In this suggestion a probable explanation of some of the apparently inexplicable accidents of aerial navigators is found. Now, while it is known to physicians that the above physiological effects can aty be produced by the lessened atmospheric pressure and a corresponding decrease of oxygen, which impairs the respiratory and circulatory processes of the body, it does not seem to have occurred to our aviators that the same effects have been observed to attack those who climb mountains, the lessened atmospheric pressure there producing the same symptoms of air sickness which are nearly constant in the order in which they manifest themselves with each increase of altitude. Each decrease of atmospheric pressure aggravates and accelerates these symptoms, which are collectively there called " mountain sickness." It has also been found that practically the same symptoms attack anyone who is shut up in a pneumatic chamber. These and other facts clearly show that the disordered physio logical conditions produced by aviation are primarily due to the progressive effects of a deficiency of oxygen supply. In the air the amount of oxygen decreases with the eleva tion, so it must inevitably follow that the swift transition in an airship from the dense atmosphere of the earth at sea-level to lofty heights in the highly-rarefied air must result in a severe shock to the respiratory and circulatory processes, and that the effects, though transient at first, must, unless counteracted, tend to become chronic if the flights in the air are often repeated or are too prolonged. At the surface of the earth at sea-level every square inch bears a weight of about 15 lbs., while at a height of a little over three miles above it the air pressure is found reduced one-half. Between these two points there is a gradual lessening of the air pressure, which has a mechanical effect on the respiratory activity of men and animals, altering it in proportion to the varied tension and density of the air. These changes chiefly affect—(1) Respiration; (2) The action of the heart ; (3) Those functions of the muscular and nervous system which are dependent on the amount of oxygen in the blood ; (4) The distribution of the blood in the vascular system. Oxygen is chemically attracted and bound by the blood cells, and the blood of an animal at rest is normally saturated with it. Moritz and Traube found that the oxidations of the body occur in the cells and not in the lungs or blood. It has been found that when the external air pressure is greatly reduced the cellular oxygen is drawn upon to supply the atmospheric deficiency, and air is given off from the blood to help the system in its struggle for existence. The haemoglobin of the red blood corpuscles carries oxygen to the body tissues. An increase in altitude is found to increase the number of red blood corpuscles, but they are diminished in size. Lack of oxygen produces deterioration and toxic conditions in the body from the retention of waste products in the lungs and glands. Gland cells deprived of oxygen decompose to a state of liquefaction. Pravaz and Campana have shown that the lungs are expanded only by the air pressure, and that when this is diminished the elastic resistance of the lungs is hard to overcome and the contraction of the lungs is more rapid and intense. The lungs of animals who die in rarefied air are found to have become atelactic, and sink in water. In the case of growing children it is found that a deficiency By F. I. WILBUR. Copyrighted by F. I. Wilbur.) in the oxygen supply tends to produce dwarf formation, for growth is impossible without oxygen. It does not seem advisable, therefore, for children to indulge in air-riding to any extent. The brain is known to require a large amount of oxygen in order properly to perform its functions. Indeed, it is now held that the evolution of mental phenomena is essen tially a chemico-vital process in which oxygenation of the cell plasma is the great feature. There is an exceptionally intimate relation between the oxygen-carrying arterial blood and cerebral function. Venous blood is absolutely fatal to normal intellectual activity, hence a progressive impairment of the mental faculties naturally follows every decrease in the oxygenated arterial blood supply. The skin has been found to be an absorber of oxygen, and hence is unpleasantly affected by a decrease in the atmo spheric supply of it. As the oxidation processes in the body are usually accom panied by heat and light, it is perfectly natural that a lack of oxygen should be followed by a lowering of bodily tem perature, which necessitates the use of warmer clothing in aerial navigation than would ordinarily be required. W. and E. Weber discovered in 1835 that the air pressure helped to retain the femur in its socket, and Dr. Faraboeuf estimated that if the air pressure fell very greatly the joint would become loose. It is probable, therefore, that very lofty or long-continued flights in the air might produce lame ness, weakness or trembling in the lower limbs. A fact of significance to aviators is that the seats of growth of the bacillus of tuberculosis in the body correspond to situa tions where there is a low pressure of oxygen. It ceases to grow in the presence of a high oxygen percentage. The development of tuberculosis, however, seems to depend on the conditions of cellular oxygenation rather than on the oxygen furnished directly from the air, for inhalations of oxygen have been found to be of no benefit in the treatment of tuberculosis, although they are advantageous in cases of air-sickness and in athletic exercises. Visits to high altitudes, are found to be especially injurious to those with heart disease or pulmonary emphysema. The advantage of carrying bags of oxygen to inhale in the high altitudes was long ago found by balloonists, and has recently been successfully used in mountain climbing. Its usefulness having been thus tested, is here commended to aviators. Sometimes the symptoms of deoxygenation become troublesome after even a change of 1,000 ft. or less of alti tude ; at greater heights they are naturally more marked. In the Peruvian highlands newcomers to the city of Cerro, which is over 14,000 feet above the sea, have the symptoms of mountain sickness in a chronic form for a long time. The symptoms of slight headache, vertigo, weakness of the limbs, a frequent and accelerated pulse without fever, nausea, faintness, coldness in the hands and feet, and a feeling of drowsiness followed by unrestful slumbers and great oppres sion at night, usually last only from six to twelve days, but the symptoms of lassitude and difficult respiration generally last a year before the person gets acclimatised. This is evi dently because the lung is the only organ of the human body whose activity can be mechanically altered by the effect of atmospheric pressure. This must be especially considered in making flights from places like Denver, Col., having a high altitude above sea-level. WTith this brief preliminary survey of the physiological conditions, let us consider somewhat in detail the specific effects which follow a decrease in atmospheric pressure. In a most interesting and scientific article on mountain sickness, much of which we quote here, George von Liebig has given a review of the conditions and symptoms which, in various parts of the world, have been found associated with decreased atmospheric pressure. For the benefit of aviators who have not studied the subject we here give a brief summary of them. The symptoms are—(1) Increased frequency of the pulse, especially under exertion ; (2) Lessened fulness of respira tion : if one walks frequent pauses are necessary in order to take deeper breath ; (3) An unusual weakness in the lower limbs, necessitating frequent rests ; (4) Great palpita- 399
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