Another scheme, more ingenious but not less fallacious, was propounded in 1670 by Francis Lana, a Jesuit, for navigating the air. This plan was to make four copper balls of very large dimensions, yet so extremely thin that, after the air had been extracted, they should become, in a considerable degree, specifically lighter than the surrounding medium. Each of his copper balls was to be about 25 feet in diameter, with the thickness of only the 225th part of an inch, the metal weighing 365 pounds avoirdupois, while the weight of the air which it should contain would be about 670 pounds, leaving, after a vacuum had been formed, an excess of 305 pounds for the power of ascension. The four balls would therefore, it was thought, rise into the air with a combined force of 1220 pounds, which was deemed by Lana to be sufficient to transport a boat completely furnished with masts, sails, oars, and rudders, and carrying several passengers. The method by which the vacuum was to be obtained was by connecting each globe, fitted with a stop-cock, to a tube of at least thirty-five feet long; the whole being filled with water; when raised to the vertical position the water would run out, the stop-cocks would be closed at the proper time, and the vacuum secured. It does not seem to have entered the head of this philosopher that the weight of the surrounding atmosphere would crush and destroy his thin exhausted receivers, but he seems to have been alarmed at the idea of his supposed discovery being applied to improper uses, such as the passing of desperadoes over fortified cities, on which they might rain down fire and destruction from the clouds! Perhaps the grandest of all the fanciful ideas that have been promulgated on this subject was that of Galien, a Dominican friar, who proposed to collect the fine diffused air of the higher regions, where hail is formed, above the summit of the loftiest mountains, and to enclose it in a cubical bag of enormous dimensions--extending more than a mile every way! This vast machine was to be composed of the thickest and strongest sail-cloth, and was expected to be capable of transporting through the air a whole army with all their munitions of war! There were many other devices which men hit upon, some of which embraced a certain modicum of truth mixed with a large proportion of fallacy. Ignorance, more or less complete, as to the principles and powers with which they dealt, was, in days gone by, the cause of many of the errors and absurdities into which men were led in their efforts to mount the atmosphere. Our space, however, forbids further consideration of this subject, which is undoubtedly one of considerable interest, and encircled with a good deal of romance. Turning away from all those early and fanciful speculations, we now come to that period in the history of balloon voyaging, or aeronautics, when true theories began to be philosophically applied, and ascending into the skies became an accomplished fact.