the dominion of the air-第4章
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y）； to be made of linen lined with paper and this machine； launched on a favourable day in the following spring； rose with great swiftness to fully a thousand feet； and travelled nearly a mile from its starting ground。
Enough； the time was already ripe for a public demonstration of the new invention； and accordingly the 5th of the following June witnessed the ascent of the same balloon with due ceremony and advertisement。 Special pains were taken with the inflation； which was conducted over a pit above which the balloon envelope was slung； and in accordance with the view that smoke was the chief lifting power； the fuel was composed of straw largely mixed with wool。 It is recorded that the management of the furnace needed the attention of two men only； while eight men could hardly hold the impatient balloon in restraint。 The inflation； in spite of the fact that the fuel chosen was scarcely the best for the purpose； was conducted remarkable expedition； and on being released； the craft travelled one and a half miles into the air； attaining a height estimated at over 6；000 feet。
From this time the tide of events in the aeronautical world rolls on in full flood； almost every half…year marking a fresh epoch； until a new departure in the infant art of ballooning was already on the point of being reached。 It had been erroneously supposed that the ascent of the Montgolfier balloon had been due； not to the rarefaction of the air within itwhich was its true causebut to the evolution of some light gas disengaged by the nature of the fuel used。 It followed； therefore； almost as a matter of course； that chemists； who； as stated in the last chapter； were already acquainted with so…called 〃inflammable air；〃 or hydrogen gas； grasped the fact that this gas would serve better than any other for the purposes of a balloon。 And no sooner had the news of the Montgolfiers' success reached Paris than a subscription was raised； and M。 Charles； Professor of Experimental Philosophy； was appointed； with the assistance of M。 Roberts； to superintend the construction of a suitable balloon and its inflation by the proposed new method。
The task was one of considerable difficulty； owing partly to the necessity of procuring some material which would prevent the escape of the lightest and most subtle gas known； and no less by reason of the difficulty of preparing under pressure a sufficient quantity of gas itself。 The experiment； sound enough in theory； was eventually carried through after several instructive failures。 A suitable material was found in 〃lustring；〃 a glossy silk cloth varnished with a solution of caoutchouc； and this being formed into a balloon only thirteen feet in diameter and fitted without other aperture than a stopcock； was after several attempts filled with hydrogen gas prepared in the usual way by the action of dilute sulphuric acid on scrap iron。
The preparations completed； one last and all…important mistake was made by closing the stop…cock before the balloon was dismissed； the disastrous and unavoidable result of this being at the time overlooked。
On August 25； 1783； the balloon was liberated on the Champ de Mars before an enormous concourse； and in less than two minutes had reached an elevation of half a mile； when it was temporarily lost in cloud； through which； however； it penetrated； climbing into yet higher cloud； when； disappearing from sight； it presently burst and descended to earth after remaining in the air some three…quarters of an hour。
The bursting of this little craft taught the future balloonist his first great lesson； namely； that on leaving earth he must open the neck of his balloon； and the reason of this is obvious。 While yet on earth the imprisoned gas of a properly filled balloon distends the silk by virtue of its expansive force； and in spite of the enormous outside pressure which the weight of air exerts upon it。 Then； as the balloon rises high in the air and the outside pressure grows less； the struggling gas within； if allowed no vent； stretches the balloon more and more until the slender fabric bursts under the strain。
At the risk of being tedious； we have dwelt at some length on the initial experiments which in less than a single year had led to the discovery and development of two distinct methodsstill employed and in competition with each otherof dismissing balloons into the heavens。 We are now prepared to enter fully into the romantic history of our subject which from this point rapidly unfolds itself。
Some eleven months only after the two Montgolfiers were discovered toying with their inflated paper bag； the younger of the two brothers was engaged to make an exhibition of his new art before the King at Versailles； and this was destined to be the first occasion when a balloon was to carry a living freight into the sky。 The stately structure； which was gorgeously decorated； towered some seventy feet into the air； and was furnished with a wicker car in which the passengers were duly installed。 These were three in number； a sheep； a cock； and a duck； and amid the acclamations of the multitude； rose a few hundred feet and descended half a mile away。 The cock was found to have sustained an unexplained mishap： its leg was broken； but the sheep was feeding complacently； and the duck was quacking with much apparent satisfaction。
Now； who among mortals will come forward and win the honour of being the first to sail the skies？ M。 Pilitre de Rozier at once volunteered； and by the month of November a new air ship was built； 74 feet high； 48 feet in largest diameter； and 15 feet across the neck； outside which a wicker gallery was constructed； while an iron brazier was slung below all。 But to trim the boat properly two passengers were needed； and de Rozier found a ready colleague in the Marquis d'Arlandes。 By way of precaution； de Rozier made a few preliminary ascents with the balloon held captive； and then the two intrepid Frenchmen took their stand on opposite sides of the gallery； each furnished with bundles of fuel to feed the furnace； each also carrying a large wet sponge with which to extinguish the flames whenever the machine might catch fire。 On casting off the balloon rose readily； and reaching 3；000 feet； drifted away on an upper current。
The rest of the narrative； much condensed from a letter of the Marquis； written a week later； runs somewhat thus： 〃Our departure was at fifty…four minutes past one； and occasioned little stir among the spectators。 Thinking they might be frightened and stand in need of encouragement； I waved my arm。 M。 de Rozier cried； 'You are doing nothing； and we are not rising！' I stirred the fire； and then began to scan the river； but Pilitre cried again； 'See the river； we are dropping into it！' We again urged the fire； but still clung to the river bed。 Presently I heard a noise in the upper part of the balloon； which gave a shock as though it had burst。 I called to my companion； 'Are you dancing？' The balloon by now had many holes burned in it； and using my sponge I cried that we must descend。 My companion； however； explained that we were over Paris； and must now cross it。 Therefore； raising the fire once more； we turned south till we passed the Luxemburg； when； extinguishing the flame； the balloon came down spent and empty。〃
Daring as was this ascent； it was in achievement eclipsed two months later at Lyons； when a mammoth balloon； 130 feet in height and lifting 18 tons； was inflated in seventeen minutes； and ascended with no less than seven passengers。 When more than half a mile aloft this machine； which was made of too slender material for its huge size； suddenly developed a rent of half its length； causing it to descend with immense velocity； but without the smallest injury to any of the passengers。 This was a memorable performance； and the account； sensational as it may read； is by no means unworthy of credit； for； as will be seen hereafter； a balloon even when burst or badly torn in midair may； on the principle of the parachute； effect its own salvation。
In the meanwhile； the rival balloon of hydrogen gasthe Charliere； as it has been calledhad had its first innings。 Before the close of the year MM。 Roberts and Charles const
