A new machine was therefore constructed, which differed in many important details from all others which had previously been made. It was twenty-seven feet in diameter, of varnished silk, and over it was spread a net of cordage. Instead of a gallery to carry the passengers, as in the “Montgolfier,” a car shaped like a boat was suspended from the net with ropes and hung a few feet below the balloon. A valve to let out the gas was also provided, and the voyagers carried in their car ballast and a barometer to indicate their height. It will thus be seen that this new balloon was in all practical details the same as the balloon of the present day.
The ascent took place on the 17th of December in Paris. Stephen Montgolfier was present, and launched a small hot-air balloon, which amused the onlookers and indicated the direction of the wind. Then MM. Charles and Roberts stepped into the car, and the balloon being liberated, they were immediately carried up to a height of 6000 feet, where a glorious panorama of Paris and the adjacent country was spread out before their delighted vision. After staying aloft about a couple of hours they descended to earth again, and Roberts got out of the car. Charles decided to continue the voyage awhile by himself, and, lightened of his companion’s weight, the balloon this time rose to 10,500 feet. The sun had by this time set upon the earth, but at this height Charles saw it rise once more and set a second time. The thermometer fell far below freezing-point, and he was benumbed with cold and felt violent pains in his ears. When at his greatest elevation he was obliged to pull the valve to prevent the balloon from bursting, and eventually descended without mischance about seven miles from where Roberts had left him.
It would be well now to describe a little more fully the way in which the “Montgolfier” and “Charlier” balloons were inflated. Each of the rival methods had its advantages and also its disadvantages. In the case of the hot-air balloon a shallow pit was dug, in which a quick-burning fire of chopped wool and straw was lighted, and the bag simply suspended over it. The inflation was thus rapid, and its cost comparatively small; the great drawback being that as the bag was of very light material, it ran considerable risk of being ignited by the fire; and all the while it was filling it was the uncomfortable duty of an unfortunate attendant to stand actually inside, roasted with the heat and choked with the smoke, armed with a paddle with which to beat out the flames whenever the bag caught alight.
Filling a Hot-Air Balloon.
This danger of fire was done away with in the method of filling with hydrogen gas. The balloon, suspended from aloft as before, was connected by hose-pipes with a number of casks containing iron or zinc filings upon which dilute sulphuric acid was poured. The effect of mixing these substances together is to set up a brisk chemical action, in the course of which hydrogen gas is given off. In this case the hydrogen thus liberated came through the pipes and filled the balloon. The great disadvantages of this method of filling—which, it may here be mentioned, is occasionally employed at the present day—are the long time it occupies, the great labour entailed, and the enormous expense.
Filling a Hydrogen Gas Balloon.