Lexicon physico-medicum: or, a new physical medicinal dictionary, explaining the difficult terms used in the several branches of the profession, and in such parts of natural philosophy as are introductory thereunto. ... / By John Quincy, M. D.

  • John Quincy
Date:
1736
Catalogue details

Licence: Public Domain Mark

Credit: Lexicon physico-medicum: or, a new physical medicinal dictionary, explaining the difficult terms used in the several branches of the profession, and in such parts of natural philosophy as are introductory thereunto. ... / By John Quincy, M. D. Source: Wellcome Collection.

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    and the Pofition of the high Moun¬ tains, which are the two principal caufes of the feveral Variations of the Wind from the former general Rule; for if a Country lying near the Sun, prove to be flat, fandy, and low Land, fuch as the Defarts of Libia are ufuaily reported to be, the Heat occafioned by the Re¬ flexions of the Sun’s Beams, and the Retention thereof in the Sand, is incredible to thofe that have not felt it * whereby the Air being ex¬ ceedingly rarefy’d, it is neceflary that this cooler and more denfe Air Ihould run thitherwards to reflore the Equilibrium: This is fuppoled to be the Caufe, why near the Coaft of Guinea the Wind always fets in upon the Land, blowing Weflerly inftead of Eaflerly, there being fuf- ficient Reafon to believe, that the inland Parts of Africa are prodigi- oufly hot, fmce the northern Bor¬ ders thereof were fo intemperate, as to give the Antients caufe to conclude. That all beyond the Tro- picks was made uninhabitable by excefs of Heat. From the fame came it happens, that there are fo conftant Calms in that part of the Ocean, called the Rains ; for this Tract being placed in the middle, between the Weflerly Winds blow¬ ing on the Coaft of Guinea, and the Eaflerly Trade-Winds blowing to the We Awards thereof, the Ten¬ dency of the Air here is indifferent to either, and fo ftands in ^equilibria between both ; and the Weight of the incumbent Atmofphere, being diminifhed by the continual contra¬ ry Winds blowing from hence, is the reafon that the Air here holds not the copious Vapour it receives, but lets it fall in fo frequent Rains. But as the cool and denfe Air, by rea¬ fon of its greater Gravity, prefles up¬ on the hot and rarefy’d, ’tisdemon- ftrative, that this latter mu ft afcend in a continual Stream, as faft as it rarefies; and that being afcended, it muft difperfe itfelf to preferve the Equilibrium; that is, by a contrary Current the upper* Air muft move from thofe Parts where the greateft Heat is : fo by a kind of Circula¬ tion, the North-Eaft Trade-Wind below, will be attended with a South-Wefterly above, and the South-Eaflerly and North-Weft Wind above. That this is more than a bare Conje&ure, the almoft inftan- taneous Change of the Wind to the oppofite Point, which is frequently found in pafling the Limits of the Trade-Winds, feems to allure usi but that which above all confirms this HypothefiSjis th tRhanomenon of the Monfoons by this means mofteafl- ]y folv’d, and without it hardly ex¬ plicable. Suppofing therefore fuch a Circulation as above,’tis to be con- fldered, that to the Northward of the Indian Ocean, there is every where Land within the ufual Limits of the Latitude of 30, viz. Arabia, Per fa, India, &c. which for the fame reafon, as the Mediterranean Parts of Africa, are fubjeft to un- fufterable Heats, when the Sun is to the North, pafling nearly vertical; but yet are temperate enough when the Sun is remov’d towards the o- ther Lropick, becaufe of a Ridge of Mountains at fome diftances within the Land, faid to be frequently in Winter covered with Snow, over which the Air, as it pafles, muft: needs be much chill’d. Hence it comes to pafs, that the Air coming according to the general Rule, out of the North-Eaft in the Indian Sea, is fometimes hotter, fometimes cold¬ er, than that which by this Circula- tion is returned out of the South- Weft ; and by confequenCe fome¬ times the under Current, or Wind, is from the North-Eaft, fometimes from the South-WefL That this has