Importance of Ike Afonigolficrs' has been made to the fact that to the brothers Montgolfier belongs the merit of being the inventors of the envelope which, when filled with liot smoke, heated air, or specifically light gas, forms the balloon, or aerostat. This merit should not be underestimated, for the invention would not have been accomplished had not the idea been recognized that such a balloon must have a consid erable diameter, and had not practical difficulties in the way of preparing a sufficiently tight and firm envelope of such enormous dimensions been successfully overcome. In fact, the first monigoyie're had a diameter of over 39 feet and weighed about five hundred pounds. The idea of utilizing the flight of the clouds or the ascension of the smoke must certainly be called ingenious.
Charles's Inijorovenzenls in Balloon 1.vith the improvement above named, monIgoyieres came in course of time to be en tirely abandoned, and subsequently have been used only for amusement, while the charlieres formed the basis of the more perfect constructions for aerial voyages and more earliest purposes. Charles, in connection with Robert, had also provided the balloon with the accessories absolutely re quired for safer ascensions and voyages. Fie devised, as above noticed, the net to carry the gondola; and to diminish at will the internal pressure of the gas, which was liable to cause explosions, as well as to discharge the gas for the purpose of descending, he arranged in the vertex of the balloon a suitable valve which as required could be opened and closed by the voyager by means of a rope carried through the balloon. He used as the material of his balloon taffeta made impermeable by the application of a solution of rubber; he provided ballast, an anchor, and an instrument for measur ing the altitude.
The Use of Balks/ was sug,gested by practical experience gained in Charles's first voyage (p. 367), when lie found that the balloon, suddenly relieved of the weight of one hundred and forty-three pounds as his com panion Robert left the car, ascended again with lightning rapidity to a height of about two miles.
Hydrogen—for the use and preparation of which in great volumes Charles was especially distingnished—however, was gradually displaced by the cheaper, though not quite so suitable, illuminating gas, and the use of this material became more general as city gas-works increased in number. The seven to eight times greater specific gravity of illuminating; gas as compared with hydrogen was counteracted by constructing larger balloons. Illuminating- gas was first used for this purpose by the Englishmen Cox well, Charles Green, and his son George, who made a great number of ascensions and aerial voyages.
Green's Greed "Nassau 7 (fii. Go) represents the bal loon used November 7,1836,by Charles Green for his voyage from London to Weilburg, in the duchy of Nassau, in which he made the distance of about five hundred miles in nineteen hours. Green was accompanied in this journey by Robert Hollond and Monck Mason, the latter of whom pub lished a very full and interesting account of the trip. The balloon con tained about 85,000 feet of gas; it was subsequently named the " Nassau Balloon," and acquired great notoriety through its frequent ascensions.
The very lame balloons constructed by Green and Coxwell (one by the latter, which ascended in 1851 at Leipsic, had a height of 66 feet and a vol ume of 35,000 feet) were, however, far surpassed by that sent up in Paris by Nadar in October, 1863.
Natiar's Balloon, "Le Geant," contained inore than 211,000 feet of gas and carried a two-story wicker-work- gondola, with physical instruments, pho tographic apparatus, food, beds, toilet-tables, etc. The unfortunate accident (pl. 6o, fig. Tr) which occuried near Nienburg, in Hanover, at the descent of this balloon, which carried nine persons, excited universal interest. The voyagers—among whom, besides Nadar and his wife, was the well-known aeronaut Godard, who acted as steersman or captain—could not provide for a sufficient escape of the gas. Hence the balloon, descending only suffi ciently to allow the heavy gondola to drag on the ground, was carried by a strong wind over hedges and ditches, damaging buildings, destroying rail road embankments, and breaking telegraph-wires, until filially it remained suspended in a forest near Rethem. The " Geant " made three more as censions in 1867. Figure 4 represents a still more disastrous catastrophe than that which happened to the " Geant"—namely, the bursting of the " Neptune," which, with the valve closed, was caught by a storm while held by a cable.
13alloon 8 shows the process of getting- a balloon ready for a voyage. The balloon is seen already filled, but held down by its net, with the aid of sand-bags. Near by are seen the large gasometers from which the supply of gas has been taken. The cables thereupon are freed from the sand-bags and connected with the car, meanwhile being lield fast by three or four ropes in the hands of attendants, who, on receiv ing the signal from the aeronaut, let go simultaneously, and the balloon starts off on its aerial voyage.