Page:Popular Science Monthly Volume 27.djvu/315

Rh Wilcox rise crowded in the cage, surrounded by forty-seven balloons fastened to it, with astonishing coolness, nodding his head to express his satisfaction and composure. After all, he could not rise above ninety-seven feet, according to the measures taken by two other gentlemen of the Philosophical Academy. He was at least five minutes in the air, but, perceiving the wind to blow from the east and drive him toward the Scoulquille [Schuylkill], he was frightened, and, agreeably to his instructions, made several incisions with a knife in three of the balloons. This was not sufficient, though we saw him descend a little. He pierced three more, and, seeing the machine did not come, his fear increased. He cut five more in the greatest haste, and, unfortunately, all on the same side. He was then seen to tack about (chavirer), and, as if he had slid down (coulé bas), he fell on the edge of a ditch and a finse [fence], as they call the inclosures. Dr. Jaune ran up; the poor man had sprained his wrist, but received no other accident."

No sooner was the fact demonstrated that men could safely rise into the air at will, than inventors began to devise plans for directing aerial machines. So long as the balloon is completely at the mercy of the wind, it is practically useless as a means of conveyance. On rising high above the ground the direction of aërial currents is often found to differ greatly from that of the surface-currents. Rising above the clouds, the aëronaut may lose sight of the earth and be carried at a rate of which he is totally unconscious, there being no means of measuring his speed when borne along with a current to which the balloon opposes no sensible resistance. By noting the times and places of ascent and descent, the rate has been estimated to exceed that of our fastest railroad-trains; and more than one aëronaut has lost his life by being carried out to sea. In the early part of 1784 M. Robert, the colleague of Charles, attempted the propulsion of a balloon by means of oars, but in vain. He subsequently tried artificial wings, but with no better success. M. Blanchard, who crossed the English Channel in 1785 with Dr. Jeffries, tried a variety of similar devices without success.

For the directing of balloons one of the first suggestions based on correct principles was offered by Francis Hopkinson. In a letter to Franklin, dated at Philadelphia, May 24, 1784, he recommends that the balloon shall be made oblong instead of spherical, and provided with a large and light wheel at the stern. "This wheel should consist of many vanes or fans of canvas, whose planes should be considerably inclined with respect to the plane of its motion, exactly like the wheel of a smoke-jack. If the navigator turns this wheel swiftly round by means of a winch, there is no doubt but it would (in a calm at least) give the machine a progressive motion, upon the same principle that a boat is sculled through the water." (Sparks's "Life and Works of Benjamin Franklin," vol. x, p. 93.) This remarkable suggestion by