Wonderful Balloon Ascents; Or, The Conquest of the Skies

atmospheric pressure. As for the idea of making use of a sail to direct the balloon, as one directs a vessel, that also was a delusion; for the whole machine, globes and sails, being freely thrown into the air, would infallibly follow the direction of the wind, whatever that might be. When a ship lies in the sea, and its sails are inflated with the wind, we must remember that there are two forces in operation--the active force of the wind and the passive force of the resistance of the water; and in working these forces the one against the other, the sailor can turn within a point of any direction he pleases. But when we are subjected wholly to a single force, and have no point of support by the use of which to turn that force to our own purposes, as is the case with the aeronaut, we are entirely at the mercy of that force, and must obey it. After the flying-machine of Lana there was constructed by Galien (who, like the former, was an ecclesiastic) an air-boat, less chimerical in its form, looked at in view of the conditions of aerial navigation, but much more singular. Galien describes his air-boat, in 1755, in his little work entitled, “The Art of Sailing in the Air.” His project was a most extraordinary one, and its boldness is only equalled by the seriousness of the narrative. According to him, the atmosphere is divided into two horizontal layers, the upper of which is much lighter than the lower. “But,” says Galien, “a ship keeps its place in the water because it is full of air, and air is much lighter than water. Suppose, then, that there was the same difference of weight between the upper and the lower layer of air as there is between the lower stratum and water; and suppose, also, a boat which rested upon the lower layer of air, with its bulk in the lighter upper layer--like a ship which has its keel in the water but its bulk in the air--the same thing would happen with the air-ship as with the water-ship--it would float in the denser layer of air.” Galien adds that in the region of hail there was in the air a separation into two layers, the weights of which respectively are as 1 to 2. “Then,” says he, “in placing an air-boat in the region of hail, with its sides rising eighty-three fathoms into the upper region, which is much more light, one could sail perfectly.”