The ancient Pantheon, at present called All Saints Church, now standing at Rome; built in the lowest Situation of a Street named the Piazza di Navona is on this Construction: and the Hint probably taken from an Egyptian Model.
241. In all inland Countries, whose Lakes are frequently surrounded by Mountains, as Bala-Pool in North-Wales; those of Westmoreland and Cumberland; the Lake of Geneva in Swisserland;—the Air rushes forcibly on the Surface of the Water in descending Torrents: this the Writer has frequently observed.[59]
(In other Languages, the Words applicable to Wind on a Lake, or the Ocean, signify Descent: as, Καταβαινω, and Επικειμαι· also the Northerly or descending Wind corresponded to the Εκνὲφιας while the Southerly or ascending Wind answered to the Απογη.)
All this, which may be allowed to take Place in bad Weather, may perhaps be excepted to, in fine, and still more so, in the finest Weather.
As the slightest Change is first observable on the Surface of Water, whether on Lakes or the Ocean, the Descent of Air in the finest Weather is familiar to Mariners by the Appellation of light airs, playing in Eddies: and particularly in the variable Latitudes; i. e. between 32 and 42: to these the Writer can also witness: as well as on small and large inland Lakes, by partial Dimplings and Rufflings of the Surface.
OBJECTION TO THE THEORY REMOVED.
242. It may be objected to the above Theory, that the Wind plainly blows in an horizontal Direction, as may be seen from the Motion of Clouds and Trees.
To which it may be answered, that if Clouds are not beside the Question; as it is not asserted that a single Column of Air presses from so great a Height to the Earth; (tho’ it be the Case in Squalls;) yet it is extremely difficult to determine whether Clouds move in a Direction exactly parallel to the Plane of the Horizon: and it is much more probable that they are in a perpetual Change, encreasing or melting; rising or falling, according to the Pressure and specific Gravity of the Medium in which they float; its Tendency to Moisture or Driness, Cold or Heat; also the different Combinations and Decompositions, with Respect to which, the Atmosphere is in perpetual Variation.
The Motion of Trees, if carefully attended to, seldom shew Effects of a regular horizontal Current.
And since the more powerful the Wind; the more evident and accurate may be the Observation; it will be found, that the first general Effect is an oblique Depression, succeeded by a Recovery or instant Exaltation: then a momentary Pause, or actual Retreat of the Wind; and in a few Seconds, a Return of the depressing Torrent.