Page:The American Cyclopædia (1879) Volume I.djvu/167

 AERONAUTICS 147 hours. The first ascent for the purposes of sci- ence was made from Hamburg on July 18, 1803, by Messrs. Robertson and Lhoest, under the direction of the Russian academy of sci- ences. A second voyage followed in the suc- ceeding month, and a third from St. Peters- burg dn June 30, 1804. But although the ex- plorers reached on one occasion an altitude of 23,526 feet, no important results were obtained. In 1804 Laplace proposed to the French acad- emy the solution, by means of observations from a balloon, of certain physical problems, and notably that of magnetic intensity at great heights. Gay-Lussac and Biot undertook to make the observations, and on Aug. 23 as- cended from Paris to the height of 13,000 feet. Their experiments in magnetism, electricity, and galvanism gave results identical with those made on the earth. The rotatory motion of the balloon having presented an unexpected obstacle to careful obervations, Gay-Lussac supplied his balloon with long hanging ropes destined to counteract this movement, and on Sept. 15 reascended alone to a height of 23,000 feet, and found a decline of temperature from 82 to 15, which almost confirmed the theory of a fall of 1 in every 300 feet of elevation. The sky was very blue and the air was found to be very dry. A magnet took a longer time to vibrate than on the earth. He was the first to bring down air collected at this enormous height, which on being analyzed was found to be in its component parts the same as the lower air. In the highest strata of air reached by the balloon he suffered severely from cold. Breathing was difficult, the pulse and respira- tion were much quickened, and the throat be- came parched. In 1806 Carlo Brioschi, the astronomer royal of Naples, in company with Andreani, the first Italian aeronaut, attempted to rise from Naples to a greater height than that attained by Gay-Lussac; but in conse- quence of the bursting of the balloon the ex- plorers were precipitated to the earth, which they fortunately reached without material in- jury. No subsequent scientific aerial expe- ditions took place till 1850, when Messrs. Bixio and Barral ascended from the garden of the observatory in Paris in a balloon filled with pure hydrogen gas. They reached a height of 19,000 feet, when an accident to their balloon compelled them to descend without having had the opportunity to make observations of much value. In a second ascent in July of the same year, they reached a height nearly equal to that gained by Gay-Lussac in his second expedition in 1804, but, owing to a tear in their balloon, were unable to rise above a bank of cloud es- timated to be 15,000 feet in thickness, and reach the blue sky beyond. The most ex- traordinary phenomenon noted by them was the sudden variation of temperature during the last few thousand feet of their ascent. At the height of 19,000 feet the thermometer marked 15, but hi the next 2,000 feet it fell to 39 be- low zero, thus showing a temperature lower by 54 than that noted by Gay-Lussac at a similar elevation. In 1852 Mr. Welsh, of the Kew ob- servatory, in company with Mr. Green, made four ascents from London in the great " Nas- sau" balloon, with results tending to confirm those already recorded by Gay-Lussac. The most remarkable and successful ascents ever made for scientific purposes were those of Mr. James Glaisher, F. R. S., from various parts of England in 1862-' 6, and of Messrs. Camille Flainmarion, W. de Fonvieille, and Gaston Tis- sandier from Paris and other parts of France hi 1867-'9. On Sept. 5, 1862, Mr. Glaisher, accom- panied by Mr. Coxwell, an experienced aeronaut who had already made 400 ascents, reached the astounding height of 37,000 feet, or 7 m. above the earth's surface. At the height of 5 m. Mr. Glaisher gradually lost the use of his limbs, and finally became totally insensible. Mr. Coxwell had meanwhile climbed up to the ring of the balloon in order to free the valve rope, which had become entangled; while doing this his hands became frozen and powerless, and he was compelled to drop down into the car and pour brandy over them to restore the circulation. He then perceived the critical condition of Mr. Glaisher, and endeavored to approach him ; but finding himself also in danger of lapsing into insensibility, and being at the same time with- out the povrer to move his hands, he seized the valve rope with his teeth, dipped his head downward several times, and found to his re- lief that the escape of gas caused the balloon to descend rapidly into a warmer temperature. Mr. Glaisher soon after revived, and they re- turned without further adventure to the earth. The results of Mr. Glaisher's observations in- duced him to abandon the theory of a decline of 1 of temperature for every increase of 300 feet of elevation. M. Flammarion calculated a mean abatement of 1 for every 345 feet when the sky is clear, and of 1 for every 354 feet when the heavens are overcast ; but Mr. Glaisher's midday experiments show that with- in the first 1,000 feet from the earth the aver- age space passed through for a decline of 1 was 223 feet with a cloudy sky, and 162 feet with a clear sky. Above 10,000 feet the space passed through for a like decline was 455 feet for the former, and 417 feet for the latter; and above 20,000 feet the space with both states of the sky was nearly 1,000 feet for a decline of 1. In an ascent made by him on July 17, 1862, the temperature was 59 at the surface; at 10,000 feet it had fallen to 26, and at 20,000 feet it had risen to 42, which shows a difference of 81 from the temperature record- ed by Bixio and Barral at the same altitude in their second ascent in 1850. Notwithstanding the difficulty of extracting any definite law from such capricious datd, the results of Mr. Glaisher's observations above quoted afford a much nearer approach to a solution of the problem than the old rule of a uniform rate of decrease. All aeronauts have been aware of the existence of atmospheric currents, often