an ascent. These gentlemen, who
had studied together at the Polytechnic School of Paris, and the latter
of whom had especially devoted himself to the study of chemistry, and
its application to the arts, while both were deeply versed in
mathematical science, were well qualified for the undertaking; and they
were warmly patronized by the government, which immediately placed at
their command the _Intrepide_, that had returned with the French army
from Egypt to Paris, after the capitulation of Cairo. M. Contel, who had
constructed the balloon, was ordered to refit it, under their direction,
at the public expense. Having furnished themselves with the
philosophical instruments necessary for their experiments--with
barometers, thermometers, hygrometers, compasses, dipping needles,
metallic wires, an electrophorus, a voltaic pile, and with some frogs,
insects, and birds--they ascended, at ten o'clock, on the morning of
August 23, 1804, from the garden of the Repository of Models. On rising
6500 English feet, they commenced their observations. The magnetic
needle was attracted as usual by iron, but it was impossible for them at
this time to determine with accuracy its rate of oscillation, owing to a
slow rotary motion with which the balloon was affected. The voltaic pile
exhibited all its ordinary effects, giving its peculiar copperas taste,
exciting the nervous system, and causing the decomposition of water. At
the elevation of 8600 feet, the animals which they carried with them
appeared to suffer from the rarity of the air. The philosophers had
their pulses much accelerated, but they experienced no difficulty in
breathing, nor any inconvenience whatever. Their highest elevation was
13,000 feet; and the result of their experiments at this distance from
the earth was, that the force of magnetic attraction had not sensibly
diminished, and that there is an increase of electricity in the higher
regions of the atmosphere.

In compliance with the request of several philosophers of Paris, who
were anxious that the same observations should be repeated at the
greatest height that could be reached, Gay Lussac alone made a second
ascent, on the morning of September 15, 1804, from the garden of the
Repository of Models, and rose, by a gradual ascent, to a great
elevation. He continued to take observations at short intervals of the
state of the barometer, the thermometer, and the hygrometer, of which he
has given a tabular view, but he unf