By the Application of the Air-Bottle, which will be to a Balloon, what an Air-Bladder, or _Swim_ is to a Fish; a concomitant Advantage is derivable. For the common Balloon and Air-Bottle, which may be called +a double balloon+, will, in their _present imperfect_ State, be able to remain a Day, or perhaps a Couple of Days in the Air: there being no Loss of Gass: unless by Evaporation, throu’ the Pores of the Silk. And this Advantage of _a double Balloon_ may be effected with little +expence+ (except that of a complete Net) to the different Proprietors, who may make alternate Voyages, with the Balloons _thus_ united: one being inflated with Gass; the other occasionally with three or more Atmospheres of common Air _condensed_. CHAPTER LX. HINTS FOR THE DIRECTION OF THE BALLOON. Sect. 315. Art. 1. In the London Chronicle, from the 20th to the 22d of August, 1785, is a Letter from Bury, containing an Account of Mr. Poole’s Balloon, with the following Circumstance, viz. “It was found necessary, before the Balloon was liberated, to cut away the Wings, intended to act as Sails, which had been constructed by an ingenious Piedmontese, patronized by +lord orford+, and which it was supposed, woud have contributed _to facilitate the Direction of the_ Balloon, but were found _greatly to retard the Celerity_ of its Motion.” Now if any Credit can be given to Newspaper Accounts, (that of the Beccles Balloon being an entire Fable,) it is to be lamented that the Wings were cut away for the Reason assigned: as it seems the only one that could properly be offered for applying them. 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.