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Aviation History
1910
1910 - 1062.PDF
\fjjCHT DECEMBER 24, 1910. THE BLOOD PRESSURE OF AVIATORS. By permission, from the "Lancet") THE wonderful triumphs of the new art of aviation have directed attention to the mechanics of the aeroplane, but the equally new problem of the physiological effects upon the aviator seems to have attracted little notice. The rapid ascent to great altitudes exposes the body to conditions different from any terrestrial ones. Mountain climbing offers some analogy, but it differs in the fact that the transition from the high atmospheric pressure of the sea-level to a low pressure takes place much more slowly. In the Gazette Hebdomadaire des Sciences Midicales de Bordeaux of September 25th Professor R. Moulinier has reported some interesting observa tions on the blood pressure of aviators who have ascended to high altitudes. On alighting after ascending to a height of 1,200 to 2,000 metres the aviator presents cyanosis of the extremities, probably from the low temperature of the high regions of the atmosphere. Often there is congestion of the conjunctiva;. The pulse is slightly accelerated, but there is no palpitation, arrhythmia, or epistaxis. There is often slight and transient headache and tinnitus aurium. Sometimes there is a tendency to sleep, and this may be felt even during flight. After the flight the blood pressure is always increased. In one aviator at 5.30 p.m., before flight, the constant blood pressure in the radial artery was found with Pachon's sphygmometer to be 9 centimetres of mercuryand the maximum pressure to be i8centimetres ; the pulse was 70. At 6 p.m., after a flight of 25 minutes, during which at the twentieth minute he reached the height of 1,100 metres, the constant pressure was 12 centimetres of mercury and the maximum pressure 19 centimetres; the pulse was 80. This increase in pressure is all the more remarkable as the aviators were athletes in full training. The rise was less marked in aviators who were fatigued. These showed palpitation of the heart and marked acceleration of the pulse (108). In one case troublesome tachycardia, symptomatic of functional insufficiency of the heart, and vertiginous movements, were observed in an aviator who, after a flight of an hour, had reached the height of 1,000 metres. No rise in blood pressure was found in aviators who flew at low altitudes, such as 100 to 150 metres. As to the cause of the rise in blood pressure, Professor Moulinier puts forward the hypothesis that it is due to the sudden descent to earth in four or five minutes from a height of 1,000 to 2,000 metres which was attained in 20 to 25 minutes. At a height of 2,000 metres the atmospheric pressure is 591 millimetres of mercury, at the sea level 760 millimetres. In the short time of the descent the circulatory system had not time to become adapted to the change of pressure. He therefore advises aviators to descend more slowly. He also points out the dangerous fatigue to which flight at high altitudes exposes the circulatory apparatus by pro voking increased and irregular activity of the heart and vessels. A sound heart and supple arteries are absolutely necessary to an aviator. The list of distressing fatalities to aviators has become comparatively long in a very short time. The accidents are always attributed to some mechanical cause—some breakdown in the machine or unexpected current of air. No doubt this is usually true, but it seems to us quite possible that in some cases the break down may have been in the human machine, which is exposed to a new and peculiar stress, both physical and psychical. It is curious that this point does not seem to have received attention. AIRSHIP AND BALLOON EWS. " Ville de Pau" in Service Again. THE Astra-built dirigible "Ville de Pau " has been taken down to the South of France for the winter and reinflated. On the 16th inst. the first ascent of the winter season was made and the dirigible cruised over the town for about an hour. Two ascents with passengers were made on Tuesday. The Belgian Military Dirigibles. THE airship " Ville de Bruxelles " has been kept waiting in the large hangar at Etterbeck for a spell of fine weather to enable the last trip of the year, from Brussels to Namur and back, to be made. As soon as this trip has been carried out the airship will be deflated and thoroughly overhauled in preparation for next season, when it in all probability will take part in the Army manoeuvres. The airship " Belgique III" will shortly be taken to Etterbeck and dismantled for overhauling with a view to its also talking part in next year's manoeuvres. New Gross Military Dirigible. THE new German dirigible of the Gross type, to be designated "M IV," which is now nearing completion, will have one gas envelope 94 metres in length and of a capacity of 8,500 cubic metres. Two cars will be fitted each containing a six-cylinder Koerting motor of 200-h.p. driving two propellers. Lung-distance Ballooning. LEAVING London on Sunday afternoon in her balloon, the Hon. Mrs. Assheton-Harbord, accompanied by Mr. C. F. Pollock and Capt. Sartorius, landed an Monday morning at La Chatre, Indre, about 130 miles due south of Paris. The attempt was made in connection with the competition for the Aero's Club's Challenge Cup. ® ® ® ® Oxy-Acetylene Welding. AMONG the firms who have devoted considerable attention to the design of oxy-acetylene apparatus for use in connection with aeroplane construction is Messrs. McGowan, Wild and Co., of Birmingham. The system adopted is that of carbide to water, the carbide being automatically fed and completely immersed in water and the gas passing through water into an accumulator. A feature of the generators made by this firm is that all joints in the apparatus are welded by the same process for which they are made, thus avoiding any leaky joints, &c. The blow-pipe used is also a special construction and designed so as to be particularly suitable of a welding of thin tubular work. The sets are made in various sizes, the smallest being arranged on wheels for ease in moving from place to place. "CLARUS" ALUMINIUM ALLOY. "CLARUS" is the registered name of a new aluminium alloy patented by Messrs. Gabriel and Co., of Birmingham, the special features of which are that it is considerably stronger than ordinary aluminium although its weight does not exceed one-third of that of brass. Whether used for castings or whether made up into the form of tubes, sheets, or wire it readily takes a high polish closely resembling silver in appearance, and is not readily tarnished by atmospheric action upon it. As regards its relative strength this is approximately 60 per cent, in excess of that of ordinary aluminium, while owing to its greater density it is, we hear, apt when being cast to be freer from air-bubbles or other defects than is the case with pure aluminium. Needless to state its lesser brittleness is greatly in its favour ; and as far as can be seen it is eminently suited for quite a considerable percentage of the fittings on motor cars and upon aerial craft. Official tests with some "Clarus" tubes show the tensile strength to be in the order of 17 tons per square inch, as against 10 tons for ordinary aluminium tube; and similarly with "Clarus" wire a tensile strength of nearly 40,000 lbs. per square inoh was obtained, as against anything from 23,000 to 28,000 lbs. with aluminium wire. Its expansion and contraction over wide variations of temperature appear to be comparatively small; and at the present time experi ments are being conducted with aluminium solder which cause it confidently to be anticipated that "Clarus" is considerably more readily soldered than aluminium. Mr, Joseph Clarkson's model direct lifting machine. The diameter is 8 ft., and it supports 12J lbs. for an expenditure of -4-h.p. 1060
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