336. 12. The Parashute to secure a Man from too precipitate a Fall, is to be 5 Yards in Diameter, when extended: the Man,—weighing 140 Pounds, and the Parashute weighing 10 Pounds, with a Surface of 150 square Feet,—woud, in that Case, feel no greater Shock than if he had fallen from the Height of six Feet. 336. 13. _Compass and its Variations: also the different Branches in Astronomy._ His Hints on the Direction of the Machine are ingenious. 337. 1. Wheels furnished with Wings. 337. 2. Imitations of the Form and Motions of Fish.[113] 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.