The French meteorologists have devised a much simpler and cheaper method of exploring the upper atmosphere, by use of small balloons carrying recording instruments. An ordinary silk or gold-beater skin balloon, partly inflated, ascends to a great height with the instruments, drifts away losing gas, and on landing is found by some one who returns it according to written directions accompanying the craft. Another method, introduced by Professor Assman, is to employ closed rubber balloons which at great altitudes burst by the expansion of the hydrogen within them, and allow the instruments to descend in parachutes softly to the ground. Instrument-carrying balloons of the above type are called “sounding balloons,” or _balloons sondes_, whereas if they carry no instruments, but merely show the course of the wind, they may be called “pilot balloons.” Such sounding balloons have been used to explore the temperature of the atmosphere to an altitude of 18 miles. In the preceding pages some extended balloon voyages have been described. These were considered very long in their day, but in recent years have been surpassed frequently, first by the professional aëronauts, then by the amateurs and members of various aëronautic clubs practicing aërostation as a sport, and stimulated by attractive prizes. But the man who achieved the longest balloon flight during the first century of the art, seems to have been Mr. John Wise, America’s foremost pioneer balloonist. Mr. Wise was a rare composite of showman, scientist, sport and dare-devil, who during the four decades succeeding his first ascension at Philadelphia in 1835, made no fewer than 440 voyages. At first the aërial art captivated him by the beauty and sublimity of the natural panoramas witnessed from on high; then he amused himself by dropping things from the basket and hearing them whistle through space; and finally he coquetted with the balloon itself, in various ways to observe the result. On one occasion the neck was choked and the valve could not be operated, so that when the hydrogen expanded with increasing altitude, it overstretched the cover and started a rent in the side of the bag. The balloon descended rapidly, but landed without injurious shock.