rapidly to the height of a mile and a half, he found himself directly above his enemies' lines. There he was able to observe perfectly their position and their movements. He then threw over ballast, and ascended to the height of three miles. At this height he encountered a current which carried him in the direction of Maryland, where he descended in safety. General M'Clellan was so much satisfied with the observations taken in the balloon, that, at his request, the order was given to the War Department to construct four new balloons.
In a preceding page, we have already mentioned that the French were the first to apply balloons to practical use for the purposes of warfare. This was in 1794. The experience then gained fully demonstrated the great utility of aeronautics; and in the disastrous Franco-Prussian War, 1870−72, balloons again played an important part—notably during the siege of Paris. When the German lines had gradually encompassed the French capital, balloon communication was organised between it and Tours, the seat of the Government, for the conveyance of despatches, and, subject to certain conditions, private correspondence. In September, 1870, the French Post Office authorities announced that they would dispatch balloons with letters as regularly as the weather would permit, beginning from the 28th of that month. M. Jules Duruof, one of the aeronauts who guided these balloons, gave an account of his adventures on a certain occasion, which will be read with interest. He "left the Place Saint Pierre Montmartre at eight in the morning of September 23rd. A strong east wind was blowing. He rose to the height of 3,000 yards, and was then driven in the direction of the Arc de Triomphe. Going still westward, he perceived
