337. 3. Vessels to condense Air, as the Bladders of Fish.
337. 4. Wind-Guns, Wind-Fountains.
337. 5. Elopile and Vapour Steam.
337. 6. Contrary Currents at different Heights: Proof of.
337. 7. New Hints for Balloons to be raised by Steam.
337. 8. Mons. Gouan’s Invention to go three hundred miles a day in a calm.
338. The general Use to which Balloons seem capable of being applied, with the Assistance of propulsive Machinery, in the Calm which exists above the Level of a contrary Wind; is that of a common Vehicle, not subject to the Inconvenience of Roads and Inns, between distant Places and Countries, for Passengers, properly accommodated in a Boat-shaped covered Car, furnished with Provisions, and occasional Siberian Cloathing: the Car to be surrounded with, and resting on Bladders, one fourth blown, and having each a few Drops of Water within, to keep them moist and elastic;—to prevent an accidental Shock in alighting on Land; and from sinking, if on Water.
Such a Conveyance (the Balloon being once made Air-tight, and furnished with an Air-Bottle to ascend and descend without Loss of Gass) is ready at all Seasons and Times: both Night and Day: for, as the Aironauts will enjoy continual Sunshine without a Cloud, from his Rising to his Setting: so, during the Night, the Light of the stars, always intercepted in its Passage to the Earth by Clouds or thick Vapours, will be greatly augmented, when above both: besides the probable Increase of Light reflected from the upper Fields of white Clouds shone on continually by the different Planets and Constellations: all which will afford an Illumination equal, if not greater, than that of a cloudless frosty Night, when the Ground is covered with Snow.
And such Light will be sufficient to read or write by: also to examine the Barometer,[114] in order to know the Height and Level of the Balloon above the Surface of the Earth; and the compass for Direction.
If Aironauts propose to ascend by Night, and in the Moon’s Quarters; observing likewise the Precautions already given; it may be proper also to consult and take with them the Ephèmeris, in order to know the Time when the Moon rises, and also when she is at the highest, i. e. in the South, or has remained about half her Time above the Horizon.