AEROSTATION. 
459 
meters, and electrometers, M.M. Biot and Gay Lussac took with 
them two compasses and a dipping needle, with another fine needle, 
carefully magnetized, and suspended by a very delicate white thread, 
for ascertaining by its vibration the force of the magnetic attractions 
in the upper regions of the atmosphere ; and to examine the electri- 
city of the difterent strata of this medium, they carried several metal- 
lic wires, from sixty to three hundred feet in length, and a small 
eleclrophorus slightly charged. For galvanic experiments, they had 
procured a few discs of zinc and copper, with some frogs, to which 
were also added some insects and birds. 
It was also proposed to bring back air collected at as great a height 
as possible ; for which purpose they had an exhausted glass ball 
closely shut ; so that to fill it with air at any place, it was only ne- 
cessary to open it, and then to stop it again with care and security. 
Thus prepared, the philosophers took their departure at ten o’clock 
in the morning of the day above stated : the barometer standing at 
23 inches 3 lines, or 30.13 inches, English ; Reaumur’s thermometer at 
13^.2, and the hygrometer at 80^.8, consequently very near to the 
greatest degree of humidity. 
The ascent was extremely pleasant and gradual, and the novelty, 
beauty, and magnificence of the spectacle, which now fo? the first 
time burst upon them, engaged all the attention of our philosophers, 
whilst the indistinct buz of distant gratulations from innumerable 
spectators gently met their ear. These first moments being past, they 
entered into the regions of the clouds, which seemed like a thin fog, 
and gave them a slight sensation of humidity. The balloon now had 
become quite inflated, and they were obliged to let part of the gas 
escape by opening the upper valve, at the same time throwing out 
some ballast to gain a greater elevation ; and in a few minutes they 
had risen completely above the clouds, which they did not enter again 
till their return. These clouds had in this situation a blueish tint, 
similar to that which they exhibit from the surface of the earth ; while 
their upper surface, full of small eminences and undulations, presented 
to the aeronauts the appearance of a vast plain covered with snow. 
At this time their altitude, computed according to Laplace’s barome- 
trical formulae, was two thousand metres, or about six thousand five 
hundred English feet, and here their observations and experiments 
first commenced. 
The balloon ascended to the enormous height of four English miles and 
one-third ; from this stupendous height; M.Gay Lussac stilt saw clouds 
at a considerable height above, but none below, although the atmosphere 
had a dull misty appearance,, which destroyed its transparent quality ; 
the limit, therefore, fixed by M. Sacharof for the greatest height of 
the clouds, is obviously erroneous. 
While occupied with experiments at this enormous elevation, M. 
Gay Lussac, though well clothed, began to suffer from excessive 
cold; and his hands, by continual exposure, grew benumbed. He felt 
likewise a difficulty in breathing, and his pulse and respiration were 
much quickened. His throat became so parched, that he could scarcely 
swallow a morsel of bread, but he experienced no other direct incon- 
venience from his situation. He had, indeed, been affected through 
