315. 2. Balloons already rise like a Rocket, and press forward almost with the Celerity of the Wind: it is therefore evident, that these Celerities must be greatly retarded, in order to facilitate the Direction: and consequently that the Wings bid fair to have answered the Intention of their ingenious Projector. And why precipitately cut them away, before the Balloon was left to the Pleasure of the Winds? since no regular or safe Manouvres ought to have been attempted, till that Time.
There appears to have been much the same Reason for rejecting the Piedmontese Wings, that there was for condemning the use of a Parashute, to which a Dog being appended was killed in the Descent: because the Parashute was not let loose at a sufficient Height, nor was it properly distended.
315. 3. It seems, that as the Wings had greatly impeded the Balloon; a certain Addition to them might have nearly stopped it in the Air.
For the Balloon having once acquired an uniform Motion, by encreasing the Surface of the resisting Body, or Wings, the Balloon maybe retarded to a certain Point. But the Resistence encreasing woud raise the resisting[105] Body above its Power of Action, and therefore, in Fact, lessen it; by which Means the Balloon woud continue to be propelled in the Direction of the Wind, with a Force equal to that Diminution.
Suppose, for Instance, that, instead of the half Mile Flag, which evidently checked the progressive Motion of the Balloon ([Section 70]) a larger square Surface, of varnished Silk, or a triangular Latteen Sail (like the Αρτεμων of Le Roi[106]) was substituted, and kept stretched, by a hollow Cane, or Yard.[107]
315. 4. Also, that by Means of a Fan or small Oar, acting as a Rudder, to be folded and taken back into the Car at Pleasure, the Balloon was compelled to move with a given Side foremost; that the Sail was let down below the Car, by strong silken Cords fastened to each Angle; and lastly, that leaden Weights, (each weighing an Ounce Averdupoise when widely perforated, and put throu’ the Ends of each Cord before it is fastened to the Car), be let down to each Angle; occasionally encreasing the Weights (or Sail) in Proportion to the Wind; which relative Weights (or Sail) will best be determined by repeated Experiments; will not such an Apparatus or Anemometer-Sail, acting as a Vis Inertiæ nearly at right Angles against the Force of the Wind, check the Balloon; till the encreasing Resistence raising the Sail upwards towards the Horizon diminishes its Power of Action? With this Sail therefore, which requires little Attention; and with the Assistance of Wings moved by Levers, pressed alternately downwards as the Bellows of an Organ, by the Feet of the Aironaut and mere Weight of his Body, standing upright near the Center of the Car; the Balloon may probably be, in some Respect, subject to Direction, and move obliquely against the Wind, or with Force in a Calm.
The Balloon and Anemòmeter-Sail, like the Earth and Moon will turn on their common Center of Gravity.
315. 5. It is possible to erect a light hollow Mast throu’ the Car, and throu’ the Balloon, by Means of a cylindrical Tube of varnished Silk, extending from Top to Bottom, in order to sustain the Balloon in an upright Situation, and make it keep Pace with the Car, when the latter is propelled by the Wings. The Mast shoud be covered with soft Cotton, to lessen the Roughness of the Friction. It may also contain within it, another slenderer hollow Mast, after the Manner of a Cane Fish-Rod; either to be lowered out, and placed horizontally across or below the Car, to serve as a Guard for the Bottom of the Anemòmeter-Sail; or to be let down to any Depth occasionally: and other Sails connected, by the usual wooden Rings, and kept tight by Cords running throu’ Blocks fastened to any Part of the equatorial Hoop, as used at first, by the gallant Admiral of the Air blanchard, and afterwards too precipitately rejected; since, in Case of a Rupture of Gass throu’ the upper Hemisphere of the Balloon; the equatorial Hoop preserves the Parashute complete: and for Want of which Hoop, young Arnold had certainly lost his Life, if the Water of the Thames had not broke his Fall.
During the Descent of the Balloon, the Sails are to be taken in, and the lower Mast projected into its Socket.
315. 6. Different Trials may be repeatedly made: the Effects of which, whether evidently useful or apparently otherwise, being carefully recorded and regularly published in Detail, may afford Data for the Prosecution of further Discoveries, and lay the Foundation for a rational Superstructure of airostatic Navigation.