i68 A E R O S T 
accelerated their courfe. From the account of their 
voyage, it would feem that they had patted fafely through 
the thunder-clouds; as we are informed, that, about forty 
minutes after three, they heard a loud clap of thunder; 
and, three minutes after, another much louder; at which 
time the thermometer funk from 77 0 to 59 0 . This hid¬ 
den cold, occafioned by the approach of the clouds, con¬ 
densed the inflammable air fo that the balloon defcended 
very hnv, and they were obliged to throw out forty pounds 
of hallaft; yet, on examining the heat of the air within 
the balloon, they found it to"be 104 0 , when that of the 
external atmofphere was only 63°. When they had got 
fo high that the mercury in the barometer flood only at 
23-94 inches, they found themfelves becalmed; fo that 
the machine did not go even at the rate of two feet in a 
fecond, though it had before gone at the rate of twenty- 
four feet in a feeond. On this they determined to try the 
effect of their oars to the utmoft; and, by working them 
for thirty-five minutes, and, marking the fliadow’ of the 
balloon on the ground, they found, in that time, that they 
had delcribed the fegment of an eliiplis whole longed dia¬ 
meter was 6000 feet. After having travelled about 150 
miles, they defcended, only on account of the approach 
of night, having ttill 200 pounds of ballatt left. 
Their conclufion, with regard to the effeCt of their 
wings, is as follows:—“ Thofe experiments Ihew, that far 
from going againfi the wind, as is laid by fome perfons to 
be poflible in a certain manner, and fome aeronauts pre¬ 
tend to have actually done, we only obtained, by means 
of two oars, a deviation of twenty-two degrees: it is cer¬ 
tain, however, that if we could have ufe'd our four oars 
we might have deviated about forty degrees from the di¬ 
rection of the wind, and, as our machine would have been 
capable of carrying feven perfons, it would have been 
eafy for live perfons to have gone, and to have put in ac¬ 
tion eight oars, by means of which a deviation of about 
eighty degrees w'ould have been obtained. 
“ We had already obferved (fay they), that, if We did 
not deviate more than twenty-two degrees, it was becaufe 
the wind carried us at the rate of twenty-four miles an 
hour; and it is natural to judge, that, if the wind had 
been twice as lirong as it was, we Ihould not have deviated 
more than one-half of what we actually did; and, on the 
contrary, if the w'ind had been only half as lirong, our 
deviation would have been proportionably greater.” 
Having thus related all that has been done with regard 
to the conducting of aeroflatic machines through the at¬ 
mofphere, we fhall now relate the attempts that have been 
made to leflen their expence, by falling upon fome con¬ 
trivance to afeend without throwing out ballatt, and to 
defeend without loling any of the inflammable air. The 
firft attempt of this kind was made by the Duke de Char¬ 
tres; who, on the 15th of July, 1784, afeended with the 
two brothers, Charles and Robert, from the Park of St. 
Cloud. The balloon was of an oblong form, made to af¬ 
eend with its longeft diameter horizontally, and meafttred 
fifty-five feet in length and twenty-four in breadth. It 
contained within it a fmaller balloon filled with common 
air; by blowing into which with a pair of bellows, and 
thus throwing in a confiderable quantity of common air, 
it was fuppofed that the machine would become lufficiently 
heavy to defeend, efpecially as, .by the inflation of the in¬ 
ternal bag, the inflammable air in the external one would' 
be condenfed into a fmaller fpace, and thus become fpe- 
cifically heavier. The voyage, however, was attended with 
fitch circumttances as rendered it impoflible to know w'hat 
would have been the event of the fcheme. The power of 
afeent with which they fet cut, feents to have been very 
great; as, in three minutes after parting with the ground, 
they were loft in the clouds, and involved in fuch a denfe 
vapour that they could fee neither the Iky nor the earth. 
In this lituation they feemed to be attacked by a w hirl¬ 
wind-, which, belides turning the balloon three times round 
from right to left, fhocked and beat it fo about, that they 
were rendered incapable of tiling any of tire means pro- 
A T I O N. 
pofed for direfling their courfe, and the filk fluff of w-hich 
the helm had been compofed was even torn away. No 
feene can be conceived more terrible than that in which 
they were now involved. An immenfe ocean of fhapelefs 
clouds rolled one upon another below them, and feemed 
to prevent any return to the earth, w'hich ttill continued 
invilible, w hile the agitation of the balloon became great¬ 
er every moment. In this extremity they cut the ebrds 
which held the interior balloon, and of confequence it 
fell down upon the aperture of the tube that came from 
the large balloon into the boat, and flopped it up. They 
were then driven upwards by a gull of wind from below, 
which carried them to the top of that ftormy vapour in 
which the-y had been involved. They now Taw the fun 
without a cloud; but the heat of his rays, with the dirni- 
niflicd denfity of the atmofphere, had fuch an effeCt on 
the inflammable air, that the balloon feemed every mo¬ 
ment ready to burft. To prevent this they introduced a 
ftick through the tube, in order to pufli away the inner 
balloon from its aperture ; but the expanfion of the in¬ 
flammable air puttied it fo clofe, that all attempts of this 
kind proved ineffectual. It was now, however, become 
abfolutely neceflary to give vent to a very confiderable 
quantity of the inflammable air; for which puipofe the 
Duke de Chartres himfelf bored tv/o holes in the balloon, 
which tore open for the length of feven or eight feet. 
On this they defcended with great rapidity; and would 
have fallen into a lake, had they not haftily thrown out: 
fixty pounds of ballatt, which enabled them juft to reach 
the water’s edge. 
The fuccefs of the fcheme for railing or lowering 
aerottatic machines by means of bags filled with common 
air being thus rendered dubious, another method was 
thought of. This was'to put a final 1 aerottatic machine 
with rarefied air under an inflammable-air balloon, but at 
fucii a diftance that the inflammable air of the latter might 
be perfectly out of the reach of the fire ufed for inflating 
the former ; and thus, by increaling or diminifhing the 
fire in the frnall machine, the abfolute weight of the whole 
would be confiderably diminilhed or augmented. This 
fcheme was unhappily put in execution by the celebrated 
M. Pilatre de Rczier, and another gentleman'named M. 
Romaine. Their inflammable-air balloon was about thir- 
ty-Teven feet in diameter, and the power of the rarefied- 
air one was equivalent to about fixty pounds. They af¬ 
eended without any appearance of danger or finifter acci¬ 
dent ; but. had not been long in the atmofphere when the 
inflammable-air balloon was feen to fwell very confidera¬ 
bly, at the fame time that the aeronauts w ; ere obferved, 
by means of telefcopes, very anxious to get down, and 
butted in pulling the valve and opening the appendages to 
the balloon in order to facilitate the efcape of as much 
inflammable air as poflible. A fiiort time after this the 
whole machine was on fire, when they had then attained 
the height of about three quarters of a mile from the 
ground. No explofion was heard; and the filk which 
compofed the air-balloon continued expanded, and feemed 
to relift the atmofphere, for about a minute ; after which 
it collapfed, and the remains of the apparatus defcended 
along with the two unfortunate travellers fo rapidly, that 
both of them were killed. M. Pilatre feemed to have 
been dead before he came to the ground ; but M. Ro¬ 
maine was alive w hen fome perfons came up to the place 
where he lay, though he expired immediately after. 
Thefe are the molt remarkable attempts that have been 
made to improve the fcience of aeroftation; though a great 
number of other expeditions through the atmofphere have 
taken place. But of all the voyages which had been hi¬ 
therto projected or put in execution, the moll daring was 
that of M. Blanchard and Dr. Jeffries acrofs the Straits 
of Dover, which l'eparate England from France. This 
took place on the 7th of January, 1785, being a clear 
frofty morning, with a wind, barely perceptible, at N. N. 
W. The operation of filling the balloon began at ten 
o’clock, and, at three quarters after twelve, every thing was 
ready 
