231. 5. But if the Air over the Water be warmer than that over Land; then the Balloon, moving into a warmer Medium, as over the Sea in frosty Weather, most undoubtedly descends: till the included Gass has received the additional Encrease of Temperature from that of the Air, at which Time it will have a Tendency to reascend, and will rest suspended in Equilibrio, as in the former Case. The above Causes however may be considered, as _trivial_. The first may be avoided by making the Balloon _Air-tight_: and the second easily guarded against by throwing out a little _Ballast_. The _only_ formidable one, if any, is +the depression of the atmosphere+. This it will be necessary to consider with some Degree of Attention. CHAPTER XXXXIII. Section 232. Whoever consults Antiquity,[54] or is acquainted with modern Mèteorism, will ascent to the Truth of the Facts there recited, viz. That the Storms of +dispersion+ called _Prester-John_, and _Ox-Eye_ over Table Bay at the Cape of Good-Hope (not to mention those of +collection+, as _Whirlwinds_[55] and _Waterspouts_;) _descend_ on Sea and Land from the _middle_ Regions of the Air, often _perpendicularly_ +downwards+: and then blow violently from a Center, to all Parts of the Compass at once: a necessary Consequence of their beating _forcibly_ upon the Land or Water. The Ancients maintained that the Origin, of Wind was a mere _Depression_ and _Percussion_ from the Cold of the middle _Region_: and it shoud be remarked that their Observations were made on the _Continent_, and in _warm_ Climates. Now what is seen to Excess in the _hottest_ and _coldest_ Climates;[56] most probably takes Place, in a less Degree, in temperate ones. Therefore, on a Change of Weather, the upper Atmosphere _descends_: whether its Effects are _Cold_, as in Winter; _Warmth_, as in Spring; _Wind_ or _Wet_; at the proper Seasons of the Year. 233. The Balloon, with which Dicker Junior ascended at Bristol, April 19, 1784, on a +windy+ Day, proved the Truth of the Conjecture: for tho’ the Aironaut threw out most of his Ballast; yet after each Ascent and Recovery, he was repeatedly darted _downwards_ +even+ with the Ground.[57] 234. A similar Event happened to Crosbie, in his Passage over the Sea from Dublin to England; for, tho’ he too discharged his Ballast, the Wind kept him _down_ and +even+ with the Water. The Weather at that Time seems to have been an Εκνέφιας, Procella, Percussion, Squall, or Tornado, i.e. a Storm of +depression+, and +dispersion+. 235. The Eknèfiai Winds come from cool Points on each Side the North. Bacon also observes that all +boisterous+ Winds, as Procella, Typho, and Turbo, have the evident Direction of a Precipice, or Projection _downwards_, more than other Winds: they seem to rush down like a Torrent or Cascade: and are then reverberated or beat back from the Earth, in all Directions.