h afterwards hydrogen gas, which had then been known for about seventeen years, was successfully employed in a balloon for the same purpose.
This seemed to render the idea of aerial navigation more feasible, and accordingly Blanchard, one of the earliest aeronauts, on his first ascent from Paris in March, 1784, provided his balloon with wings and a rudder, but found them useless.
After this we hear little of attempts to guide or propel balloons through the air until about 1843, when Mr. Monck Mason proposed the Archimedean screw as a motor, and constructed an egg-shaped balloon, which was placed on a wooden frame in the form of a canoe, with an Archimedean screw at one end and an ovalshaped rudder at the other.
A model of this machine, set in motion by a screw moved by clockwork, was propelled around a room by this means; but the larger machine appears to have met the fate of all its kindred contrivances.
About the same time, a Mr. Henson, in England, patented a machine consis