By this period a revival of aeronautics in the land of its birth had fairly set in. Since the last ascents of Gay Lussac, in 1804, already recorded, there had been a lull in ballooning enterprise in France, and no serious scientific expeditions are recorded until the year 1850, when MM. Baral and Bixio undertook some investigations respecting the upper air, which were to deal with its laws of temperature and humidity, with the proportion of carbonic acid present in it, with solar heat at different altitudes, with radiation and the polarisation of light, and certain other interesting enquiries. The first ascent, made in June from the Paris Observatory, though a lofty one, was attended with so much danger and confusion as to be barren of results. The departure, owing to stormy weather, was hurried and illordered, so that the velocity in rising was excessive, the net constricted the rapidly-swelling globe, and the volumes of out-rushing gas half-suffocated the voyagers. Then a large rent occurred, which caused an alarmingly rapid fall, and the two philosophers were reduced to the necessity of flinging away all they possessed, their instruments only excepted. The landing, in a vineyard, was happily not attended with disaster, and within a month the same two colleagues attempted a second aerial excursion, again in wet weather. It would seem as if on this occasion, as on the former one, there was some lack of due management, for the car, suspended at a long distance from the balloon proper, acquired violent oscillations on leaving the ground, and dashing first against a tree, and then against a mast, broke some of the instruments. A little later there occurred a repetition on a minor scale of the aeronauts' previous mishap, for a rent appeared in the silk, though, luckily, so low down in the balloon as to be of small consequence, and eventually an altitude of some 19,000 feet was attained. At one time needles of ice were encountered settling abundantly with a crackling sound upon their notebooks. But the most remarkable observation made during this voyage related to an extraordinary fall of temperature which, as recorded, is without parallel. It took place in a cloud mass, 15,000 feet thick, and amounted to a drop of from 15 degrees to -39 degrees.