CHAPTER LIII.
ON THE MEANS OF SUSTAINING A BALLOON ABOVE THE SURFACE OF THE WATER, BY A TEMPORARY LOSS OF BALLAST: AND OF RECOVERING THE BALLAST.
Sect. 294. Art. 1.THE two Inconveniencies arising from a Discharge of Ballast, while the Balloon is under the Pressure of a mediocèanal Column of Air, are,
1. First, lest the Balloon shoud rise too high; for by opening the Valve in order to descend; Gass escapes: which is an actual Loss: and the Balloon is rendered incapable of supporting its Burden at the same Height, as before.
2. The present Impossibility of resuming the Ballast, in order to descend, or check the Elevation, on approaching either Shore, or at any other Time.
294. 2. These Inconveniencies are to be remedied by the following Methods.
If Sand be the Ballast fixed on; put as much of it into a Bladder by Means of a Tin Funnel, as, when less than half blown, it will contain, without sinking below the Surface of fresh Water.
Prepare the intended Weight of Ballast, in Bladders, after the same Manner.
Also to each Bladder with Ballast, tye another Bladder without Ballast, half blown.
Tye fast each Set of Bladders, so prepared, with a leathern Thong; the Ends of which may be left a few Inches to spare.
The Grapple may remain in the Car.
294. 3. When the Balloon begins to descend over Water; lower out the Cable, by Degrees.
Tye a Pair of Bladders, one of which contains Ballast, very tight, round the End of the Cable.
Then a second Pair, at such a Distance that the intermediate Part of the Cable, will float.
Repeat this Process, till the proper Effect is obtained; or the whole Ballast is discharged.
294. 4. The Car and Balloon may be hauled or wound down to the Surface of the Water: and the Ballast resumed, as the Balloon approaches the Shore.
294. 5. If it be found necessary, the Ballast may be discharged by cutting the thongs, gradually: or the cable, at once.
294. 6. If the Wind be contrary, and the Weather moderate; the Tide, or Stream may, by Calculation and Foresight, be made to serve the Purpose of the Aironaut, in towing the Ballast which floats on its Surface: and thus checking, or gently drawing the Balloon after it.
294. 7. In such Cases, the Aironaut woud do well in applying his propulsive Machinery.