The balloon was also at an early period taken advantage of for making scientific experiments in the elevated regions of the atmosphere. With the view of ascertaining the force of magnetic attraction, and of examining the electrical properties and constitution of the atmosphere at great elevations, two young, enthusiastic French philosophers, MM. Biot and Gay Lussac, proposed to make 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.