AERONAUTIC VOYAGES 



PERFORMED 



WITH A VIEW TO THE ADVANCEMENT OF SCIENCE. 



Translated for the Smithsonian Institution from the works of Francis Arago, late secretary 

 of the French Academy of Sciences, Sfc. 



I. — THE INVENTION OP BALLOONS. 



Man, by reason of Lis weight, and the weakness of his muscular power, 

 seemed doomed to creep on the surface of the earth, and to have been disquali- 

 fied for studying the physical properties of the higher regions of our atmosphere, 

 except through the toilsome ascent to mountain summits. But what ditKculties 

 are there over which genius, united with perseverance, will not eventually tri- 

 umph 1 From the most remote times the idea of soaring into the air, far above 

 all terrestrial objects, by means of machines which the imagination endowed 

 with pi'operties unfortunately of impossible attainment, has never ceased to oc- 

 cupy the human mind. Who has not heard of the attempts of Dedalus and 

 Icarus, of the projects of Koger Bacon, and of Fathers Lara and Galen ? But, 

 until 1783, it had been granted to no one to realize the dream of so many ages. 

 Joseph i\Iichel Montgollier, who was born in 1740, at Annonay, in the depart- 

 ment of the Ardeche, and who died, a member of the Academy of Sciences, in 

 1810, had calculated that through the rarefaction, by means of heat, of the air 

 contained in a pajDcr balloon of a certain extent, an ascensional force might be 

 given it sutficent for elevating men, animals, and any desired instruments. So 

 much confidence had he in his theory that he did not hesitate to undertake, June 

 5, 1783, a public and formal exhibition before the deputies of the provincial 

 estates of Vivarais, a,ssembled at Annonay. Montgolfier has himself described, in 

 the following terms, this first experiment, which forms an epoch in the history of 

 the most important discoveries : " The aerostatic machine was constructed of 

 canvas, lined with paper, and covered by a network of twine attached to the 

 canvas. It was nearly of a spherical form, and of a circumference of 110 feet, 

 (35™.73 ;) a frame of wootl, 16 feet square, steadied it on its base. * Its capacity 

 was about 22,000 cubic feet. It, therefore, displaced, supposing the mean weight 

 of the air equal to g^^ of the weight of water, a mass of air equivalent to 1,980 

 pounds, (969 kilograms.) 



" The weight of the gas (heated air) was nearly half that of the air, for it equal- 

 led 990 pounds, and the machine, with the frame, weighed 500 pounds. For the 

 rupture of equilibrium there remained, therefore, 490 pounds, as was found con- 

 formable to the experiment. The diiferent pieces of the balloon were fastened 

 together simply by means of button-holes and buttons. Two men sufficed to 

 lift and fill it Avith gas, but it required eight to retain it. When released, at a 

 given signal, it mounted with an accelerated velocity, though less rapid towards 

 the end of the ascension, to the height of 1,000 toises, (upwards of 6,000 feet.) 

 A wind,. scarcely perceptible at the surflicc of the earth, bore it to the distance 

 of 1,200 toises from the place of departure. It remained ten minutes in the air. 

 The loss of gas by the button-holes, needle punctures, and other imperfections, 

 prevented any longer suspension. The wind was, at the time, southerly 



