w 



N 



\\ 



r 



N 



T 



ilrative, that this latter muft afcenJ in a continiuil 

 llream as fall as it rarefies ; and that being afcended, 

 it mufl: difperfe icfelf to prefcrve the equilibrium, that 



IS, by a contrary current the upper air mud move 



from thofe parts where th 



kind of circulation, the north-ea(l trade Wind below 



That 



greatell heat is 



fo, by 



will be attended with a fouth-wefterly above, 

 this is more than a bare conje6ture, the almofl: inftan- 

 tancous change of the Wind to the oppofite point, 

 which is frequently found in pafllng the limits of the 

 trade Winds, feems to allure us -, but that which above 

 all confirms this hypothefis, is the phsenomenon of 

 the Monfoons, by this means mod eafily folved, and 

 without it hardly explicable. 



Suppofing therefore, fuch a circulation as above, it 

 is to be confidered, that to the northward of the In- 

 dian ocean, there is every where land within theufu- 

 al limits of the latitude of thirty degrees ; viz. Ara- 

 bia, Perfia, India, &c. which for the fame reafon as 

 the mediterranean parts of Africa, are fubje6t to un- 

 fufferable heats, when the fun is in the north, paffing 

 nearly vertical ; but yet are temperate enough, when 

 the fun is removed toward the other tropic, becaufe 

 of a ridge of mountains at fome dillance within the 

 land, faid to be frequently in winter covered with 

 fnow, over which the air, as it pafles, mufl needs be 

 much chilled. 



Hence it comes to pafs, that the air, coming accord- 

 ing to the general rule, out of the north-eaft in the 



and received into the open air, chofc ficrv :x\\^\ rnin> 



meteors 



are on 



rs, which fix upon mails and iides of the fhips^ 

 ly nitrous particles condenled by thecircuniam' 

 bient cold, and like that which the chemiits call uhof- 

 phorus, or artificial glow-worm, fiiinc and cait a ii./ht 

 but have no heat. ^ ''* 



This gives the lecond notlc 



<^ 



to the mariners, that the 



ftorm is rinng ; for the iea begins to be rouc-h upon 

 the firll breaking out of the Wind, and the wa'ves 

 fwell and rife, though the air at the fame time is calm 

 and clear. 



This boiling fermentation of* the fea caufes the va- 

 pours to arife, which by the intenfenefsof the circum- 

 ambient cold, are condenfed into thick clouds, and 

 fall down in florms of Wind and rain ; firft upon the 

 fea, from whence they rofe ; and then the attradlive 

 power of the mountain cold, by a fecrct mia^rnetifm 

 between vapour and cold, attracts the waterifh va- 

 pours, and intermixed with nitrous particles, they 

 afcend to the high tops of mountains and hills, where 

 they hang hovering in thick fogs, and watery mills, 

 until the atmofpherical heat rarefies the nitrous part 

 of the fog, which is almoft uppermod, and appears 

 white and tranflucent, into briilv gales of Wind. 

 And the intenfenefs of the atmofpherical cold hav- 

 ing attrafted the vapours into the colder regions of 

 the air, where they are condenfed into clouds, the 

 Wind breaks, diffipates, and drives them before it, 

 till they fall down in rain, and v/ater the furface of 



Indian fea, is fometimes hotter, fometimes colder, than the earth. 



that which by this circulation is returned out of the And this feems to be the reafon why they have but 



fouth-weft ; and by confequence, fometimes the under 

 current or Wind is from the north-eaft, fometimes 

 from the fouth-weft. 



That this has no other caufe, is clear from the times 

 wherein thefe Winds fet, viz. in April, when the fun 

 begins to warm thofe countries to the north, the 

 fouth-weft Monfoons begin, and blow during the heat 

 till October ; when the fun being retired, and all 

 things growing cooler northward, and the heat in- 



the fouth, the north-eaft enter and blow 

 all the winter, till April again. A.nd it is undoubt- 

 edly from the fame principle, that fouthward of the 

 equator, in part of the Indian ocean, the north-eaft 

 Winds fucceed the fouth-eaft, when the fun draws 

 near the tropic of Capricbfh. "^^ ^"^ 

 But in this latter occurs a difficulty ii& well to be ac- 

 counted for, which is, why this chatige of the Mon- 

 foons fliould be any more in this ocean, than in the 



creafing to 



•-•- T V 







-(Ethiop 



Wind 



Wind 

 countries where they have no mountains. 

 Dr. Derham fays. Wind is a current of the air; and 

 that which excites or alters its current, may juftly be 

 faid to be the caufe of Wind. 



An equipoife of the atmofphere produces a calm; but 

 if that equipoife be taken off, more or lefs, a ftream 

 of air or Wind is accordingly thereby oroduced. cither 

 ftronger or weaker, fwifteror flowen 

 And there are divers things that may caiife fuch al- 

 terations in the^equipoife or balance of the atmofphere, 

 viz. eruptions of vapours from the fea and land, ra- 

 refadtions and condenfations in one place mdre' than 

 in another, the falling of rain, preflure of the clouds, 



:.-lt is obferved of caves, that they always emit Winds 

 ■^:-rmoreor lefs ; and as great caves, fo great lakes alfo 

 •fend forth Winds ", but the mQft univerfal and con- 



ftant alterations of the atmoiphere {ire produced by 

 heat and cold. ->- ^.^^-^ . 



rs'^'.^^ 



year 





Wind 



• ' 



k is^ like wife jery hard ^^o conceive,^ why the limits | betw^eri tfie tropics, blow all the yearlrom eaft to 



weft ; if the caufe of this be (according to the opinion 

 of fome ingenious men) the daily progrefs of the fun 

 round that part of the globe, and by his heat rarefy- 

 ing one part of the air, while the cooler and heavier 

 air behind prefles after. " < -^ 



And fo the land and fea breezes ; and fo in our cli = 



Winds 

 degree of latitude all round the globe ; and that they 

 ftiQuld fo feldom tranfgrefs or fgll Ihort of thofe 

 bounds ; as alfo that in the Indian fea, only the north- 

 ern part fhould be fubjeft to the changeable Mon- 

 foons, and in the fouthern there fhould be a conftant 

 fouth-eaft. 



] . 



- ■ 



This account of Wind is taken from the learned Dr. 

 Halley's difcourfe on this fubjed, Pfailofoph. Tranf 



mate. 



Winds 



183. 



^ -s ^1, 



iXrjr .- 



• L 



*-,: 



1 - 



«■ 



The Rev. Mr. Robinfon gives this accpunt of the ori- 

 gin of Wind • that in the greatefl probability it pro- 

 ceeds from vaft fwarms of nitrous particles, which rife 

 from' thfe bottom of the fea, and have teen put into 

 motion, cither by the central fire, or by that heat 

 and fermentation which abounds in this hucre body 

 of the earth; and therefore this firft commotion, which 

 is. excited by the faid fermentation, is called a bot- 

 tom Wind, which is prefently difcovered by the por- 

 poifes, and other fea fifh, that delight to fport ap^^ 

 play upon the waves of the fea, and by their playin , 



~ive to the mariners the firft notice of an approachin'S 

 :orm.. rtr & 



When thefe nitrous fwarms are rifen toward the fur- 

 ^ce of tlie fea, they caufe, in a dark night, fuch a 

 ftiining light upon the waves, as if the fea were on 



fire ; and being delivered from the brackilh water. 



commonly efteemed the caufeof warm and cold wea- 

 ther) are really the effeds of the cold or warmth of 

 the atmofphere. ' '' "" ' " 





Of this Dr. Derham fays, he has Had fo many confir- 

 mations, that he does" not doubt of it ; arid he pro- 



duces for an inftance of it, that it is hot uncornmon to 



g> 



fee a warm foutherly Wind, on a fudden change to 

 the north, by the fall of fnow or hail ; and in a cold 

 frofty morning, to fee the Wind north, arid to wheel 

 about toward the foutherly quarters, when the fun 

 has well warmed the air ; and then again, in the cold 

 evening, to turn northerly or eafterly. -- 

 And hence alfo it is, that the Winds and clouds are 

 oftentimes contrary to each other in thunder fliowers 

 (efpecially if hail falls ;) the fultry weather below di- 



Wind 



-'.'/* 



, another way. 

 And that he has obferved 

 .the morning has 



Wind 



^ ■ -- 



■ 1 



J r 



+ 



1 - t 



V . 



,* 





ftirring was ^ weft-fouth-weft, that the clouds were 



vv- - ,-,v •., ^ • ' . ':.-:<^u V.K •: . — thick 



I .. 



"■<'-■■■- »■ 



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