Sect. 268. Art. 1. THE Author is well informed, that, during an Engagement at Sea;—in ten Minutes after the Action has commenced;—tho’ it blew a Gale before; (that is, tho’ it blew violently;) the Agitation of the Air, arising from the Explosion of the great Guns, and small Arms, woud counteract the Wind, and produce a dead Calm.
268. 2. Quere: does not the new elastic Air, produced from the Nitre,[80] give an instantaneous Compression and Dilatation to the incumbent atmospheric Air, round the Place of Action, while the lighter floguisticated Air passes throu’ it, raising, and affecting to its highest Limit, the whole Atmosphere. And does not the Effect of a sudden Calm, suppose the Wind to descend from above with a Kind of saltatory Motion, instantly counteracted by the new elastic Air?—For if the Wind be supposed to blow sideways or horizontally, to any considerable Height above the Water, woud not the fresh lateral Air glide away, and prevent the Continuance of the Calm?
269. When a Squall happens, or only Rain falls; Air will rush from all Sides, and from above, to supply the Vacancy of the fallen Cloud and Vapour.
The Air immediately above must fall: the lateral Air gravitating towards other Places. Hence Cold, and a bright Sky after Rain.
270. The Theory of Accumulation may account for the frequent warm Rains in Winter, and during the Night.
For the preceding diurnal Accumulation over the Sea, may circulate during the Night, at a great Altitude, to restore the Equilibrium and Loss of cold Land Air sent by a low or Ground-Wind to Sea, during the Day-Time: particularly, as the Accumulation over the Sea, during Winter, is almost continual.
271. The Wind would more frequently be perceived to descend and rebound upwards, (Trials of which might be made by holding an Umbrella, extended at right Angles with its Axis, upright in the Hand;) if the same Opportunity offered, of opposing as great a Surface to it in a perpendicular, as is every Day done, in an horizontal Direction: for in walking, the whole Height of the Body, and half its Surface, is opposed horizontally to the Wind: but the Head only, which is covered, is opposed to the perpendicular Pressure.
272. As every Circumstance in the Order of Nature is so admirably contrived that each apparent Inconvenience rectifies itself; in heavy Winds continuing to blow from a cold Point; the Construction of the Atmosphere is such, that the warm light Air from the opposite Points will necessarily rise up and flow over the cold Stratum, and by their Tendency to an Equilibrium, will produce an Air less cold, before the same Wind is exhausted.
273. On the one Hand; it is probable, that, as cold Winds are heavy; the Eknèfiai Winds are covered with frequent Waves of the Apogay, or light warm Air rolling over them, frequently from the opposite Points.
274. On the other Hand, as the Apogay Winds are naturally light and warm, it is improbable that they shoud be frequently covered with Waves of cold heavy Air, rolling over them from Eknèfiai Points.