Curiously enough, Napoleon would make no use of balloons in his campaigns, and even did away with the balloon school at Paris. The reason given for his prejudice is a curious one. At the time of his coronation a large, unmanned balloon, gaily decorated, and carrying thousands of lights, was sent up from Paris during the evening’s illuminations. It was a very beautiful object, and behaved splendidly, sailing away into the night, amidst great popular rejoicing, until it was lost to sight in the darkness. But at daybreak next morning it was seen approaching the city of Rome, where it presently arrived, actually hovering over St. Peter’s and the Vatican. Then, as if its mission were fulfilled, it settled to earth, and finally fell in Lake Bracciano. But as it fell it rent itself, and left a portion of the crown with which it was ornamented on the tomb of the Roman Emperor Nero. Napoleon, who was always a superstitious man, saw in this extraordinary voyage some dreadful forecast of his own fate. He was much disturbed, and forebade the matter ever to be mentioned in his presence; nor would he henceforward have any more to do with balloons. [Illustration: AMERICAN WAR BALLOON.] Military balloons were used by the French again, however, during their war in Africa in 1830. The Austrians also used them in 1849, and it is said the Russians had them at the siege of Sebastopol in the Crimean War. A Montgolfier balloon was made use of by the French in 1862 at the battle of Solferino; and the Americans also employed balloons during the Civil War a year later. The American war balloons were comparatively small ones, inflated with hydrogen. The hydrogen was manufactured in the way already described, by pouring dilute sulphuric acid upon scrap-iron. For making the gas upon the field two large tanks of wood called “generators” were used. In these the water and scrap-iron were placed and the acid poured upon them, the gas produced being carried to the balloon through pipes, passing first through vessels filled with lime-water to cool and purify it. When on the march four waggons were sufficient to carry the whole apparatus. The inflation, which took some time, was made as close to the scene of action as was considered safe, and when the balloon was once full a party of men could easily tow it about to where it was needed. But the time when the balloon was most largely and most usefully used in time of war was during the Siege of Paris. In the month of September 1870, during the Franco-Prussian War, Paris was closely invested by the Prussian forces, and for eighteen long weeks lay besieged and cut off from all the rest of the world. No communication with the city was possible either by road, river, rail, or telegraph, nor could the inhabitants convey tidings of their plight save by one means alone. Only the passage of the air was open to them.