AEROSTATION. 
mospheric air, and rise in it. This thought 
was suggested in his lectures in 1767 or 
1768 ; and he proposed, by means of the 
allantois of a calf, to try the experiment. 
Other employments, however, prevented 
the execution of his design. The possibi- 
lity of constructing a vessel, which, when 
filled with inflammable air, would ascend -in 
the atmosphere, had occurred also to Mr. 
Cavallo, about the same time ; and to him 
belongs the honour of having first made ex- 
periments on this subject, in the beginning 
of the year 1782, of which an account was 
read to the Royal Society, on the 20th of 
June in that year. He tried bladders ; but 
the thinnest of these, however scraped and 
cleaned, were too heavy. In using China 
paper, he found that the inflammable air 
passed through its pores, like water through 
a sieve ; and having failed of success by 
blowing this air into a thick solution of 
gum, thick varnishes, and oil-paint, he was 
under a necessity of being satisfied with soap- 
bubbles, which being inflated with inflamma- 
ble air, by dipping the end of a small glass 
tube, connected with a bladder contain- 
ing air, into a thick solution of soap, and 
gently compressing the bladder, ascended 
rapidly in the atmosphere ; and these were 
the first sort of inflammable air-balloons that 
were ever made. For balloons formed on a 
larger scale, and on the principle of rarefied 
air, we must direct our attention to France, 
where the two brothers, Stephen and Jo- 
seph Montgolfier, paper-manufacturers at 
Annonay, about 36 miles from Lyons, dis- 
tinguished themselves by exhibiting the first 
of those aerostatic machines, which have 
since excited so much attention and as- 
tonishment. The first idea of such a ma- 
chine was suggested to them by the natural 
ascent of the smoke and clouds in the at- 
Uiosphere ■ and the first experiment was 
piade at Avignon, by Stephen, the eldest 
of the two brothers, towards the middle of 
November 1782. Having prepared a bag 
of fine silk, in the shape of a paralelepipe- 
don, and in capacity about 40 cubic feet, 
he applied to its aperture burning paper, 
which rarefied the air, and thus formed a 
kind of cloud in the bag, and when it be- 
came sufficiently expanded, it ascended 
rapidly to the ceiling. Soon afterwards the 
experiment was repeated by the two bro- 
thers at Annonay in the open air, when the 
machine ascended to the height of about 
seventy feet. Encouraged by their success, 
they constructed a machine, the capacity 
of which was about 650 cubic feet, which, 
in the experiment, broke the ropes that 
confined it, and after ascending rapidly to 
the height of about 600 feet fell on the ad- 
joining ground. With another machine, 
35 feet in diameter, they repeated the expe- 
riment in April 1783, when breaking loose 
from its confinement, it rose to the height 
of above 1000 feet, and being carried by 
the wind, it fell at the distance of about 
three quarters of a mile from the place 
where it ascended. The capacity of this ma- 
chine was equal to about 23,430 cubic feet ; 
and when inflated, it measured 117 English 
feet in circumference. The covering of 
it was formed of linen lined with paper, 
its shape was nearly spherical, and its aper- 
ture was fixed to a wooden frame about 16 
feet in surface. When filled with vapour, 
which was conjectured to be about half as 
heavy as common air, it was capable of lift- 
ing up about 490 pounds, besides its own 
weight, which, together with that of the 
wooden frame, was equal to 500 pounds. 
With this machine the next experiment was 
performed at Annonay, outlie 5 th of June 
1783, before a great multitude of specta- 
tors. The flaccid bag was suspended on a 
pole 35 feet high; straw and chopped wool 
were burnt under the opening at the bot- 
tom ; the vapour, or rather smoke, soon in- 
flated the bag, so as to distend it in all its 
parts ; and this immense mass ascended in 
the air with such a velocity, that in less than 
ten minutes it reached the height of about 
6000 feet. A breeze carried it in an hori- 
zontal direction to the distance of 7668 feet ; 
and it then fell gently on the ground. M. 
Montgolfier attributed the ascent of the ma- 
chine, not to the rarefaction of the heated 
air, which is the true cause, but to a certain 
gas or aeriform fluid, specifically lighter than 
common air, which was supposed to be dis- 
engaged from burning substances, and which 
has been commonly called Montgolfier’s 
gas, as baloons of this kind have been deno- 
minated Montgolfiers. As soon as the news 
of this experiment reached Paris, the philo- 
sophers of the city, conceiving that a new 
sort of gas, half as heavy as common air, had 
been discovered by Messrs. Montgolfier; 
and knowing that the weight of inflammable 
air was not more than the eighth or tenth 
part of the weight of common air, justly con- 
cluded, that inflammable air would answer 
the purpose of this experiment better than 
the gas of Montgolfier, and resolved to make 
trial of it. A subscription was opened by 
M. Faujas de St. Fond towards defraying 
the expense of the experiment. A sufficient 
