WIN 



thick and black (as they generally" are wlien fnow 

 follows ',) and that, a liccie before noon^ the WinU 

 veered about to the north by weft, and fometimes to 

 other points; the clouds at the fame'time flying, 

 fome north by weft, and fpmcfouth-weft; thataboui 

 one o'clock it rained apace, the clouds fometimes 

 flying north-eaft, then north ; and at laft both Windc 

 and clouds have fettled north by weft V and at that 

 time' the fleet fell very plentifully, and 

 very cold. ■ ■ • ' ■ "■ '■ ._.:;.■;-■ ; 



W^i 



r 



1 4 



' --* 



/ « 



- '): 



t 





of the produnion'y'i^c. of 



•('. 



.f. * 



It grew 



From all which he obferves ; ' '^' 





\ 



. ■ iV If the fpring'of the air be wealc^ned in any place, 

 ' morethan'in the adjoining places, a Wind will blow 



through the place where the diminution i^.'' * ' '* 

 t For fince the airendeavours'by'its'elaftic'farc^ toVx- 

 pand itfelf every way, if that force be lefs In one 

 -' place than another, the nifus df the more againft the 

 ■ lefs claftic will be greater',* 'thsin the nifus 'of the lat- 

 ter againft the former.-^The kfs elaftic air^'thcre- 

 • fore, will refift with lefs force than it is urged iJy the 

 more elaftic ; confequetitly, the lefs elaftic'will be 

 Firft, that though the region below was warm, the I ''driven out of its place, and the more claftic will 

 region of the clouds was cold, as the black fnowy I ■•^^^^^'>'^- *--• -'!•'-- > :r';; a . ■■a <■; ,->/:,. 



■ clouds ftiewed. . ^' • • r v"^ ;X?fe' ■ • • 



Secondly, That the ftruggle between the warmth of 



our region, and the cold of the cloudy region ftoppec^ 



the airy currents of both regions.' • •' *'* : ' . - 



Thirdly, That the falling of the fnow through oui 



warmcf air, did at firft melt into rain ; but after the 

 ' fuperior cold had conquered the inferior warmth, ii 



became fleet. ' - -■■ ■'"■'-' ^ - - j ■ • - ■ 



fucceed. . . ^ 



■ If now the excefs of the fpring of th^ more elaftic, 

 to that of the lefs elaftic, be fuch as to occafion a little 

 alteration in the barofcope, the ifidtidn BbtH df the 



' air expelled, and that which fucceeds it will become 



2.' Hence, fince the fpring of the air ihcreafes/'as the 



Fourthly, That as the cold prevailed by degrees, it 

 wheeled about both the Winds and clouds, from the 

 northward towards the fouth. 



It is not at all improbable, that there is often afiem- 



bled in the atmofphere, a fufficient" quantity of va- 



' pours to maintain a lafting cbridenfation';^ and that it 



is alfo quick enough at fome times to create a great 



Wind. •^■^" ' ■' ■^-"- -;:--iy.- --:.'^-/^:'^ ^-(>-> ;-'^^-.— 



' For according to Dr. Halley's experiment, it may be 

 ^ computed, that there is 129,762,2 i9_cubical miles of 

 the atmofphere filled by vapours every day. This pro- 

 ■'. digious'qOlntlty; being divided and ranged in bodies 

 • at various fituations throughput the world, occafions, 

 ' by the mutual condenfations, almoft conftant refults 

 of the air, to fupply the empty places j fo may be 

 thought abundantly fufficientfor producing and main- 

 taining all Winds univerfaUy. . ■ . r 

 From thcfe and other confiderations, it may be con- 

 ^, eluded, that the production of Winds depends chiefiy 

 -'on the"coridenfation of Vapours; and in order to con- 

 firm- this hypothefis, we fliail proceed to explain feve- 

 ,- ral properties and cafes folvable thereby. ^^ : ' 

 , I. That the direction or courfe of any Wind is accord- 

 . ing to the fitu^tion of the" i&o3y of vapours, whbfe 

 - condenfation produces it ; fo if a concourfe of vapours 

 Be gathered over the kingdom of France, the conden- 

 fation thereof would draw the air from England in a 

 foutherly direftioh, in Spain would be a northerly 

 Wind^ in Germany would blow wefterly, at the Bay 



of Bifcay an eafterly Wind. 



2. That the force or intenfity of a Wind is the exten- 



fion of the condcnfing vapour, and the quickhefs:of 



derifer than air lefs cdmpreflfed, all Winds 

 rarer air out of a place filled with a denfer. 

 i. Wherefore fince a denfer air is foecific; 



y . 



•'» 



;'' any pLice, muft be attended with extraordinary Winds 



'■■' or llorms. , ■ . . 



Now an extraordinary fall of the mercury in the ba- 

 rometer, fnews an extraordinary lightnefs of the at- 



■'"mofphereV therefore it is 'rib' wonder if that foretels 



Itorms. -'•• -7r . , -f / 



- JH.. \^%^r 



* * 



I ^ 





i*» 



» r 



/ 





< i 







their condenfations. 



^. x.w. ....^ o v,/H,Wind 



about the equinoxes than at other feafons.^^; ^ •'*■ ;' 

 4 We muft add that it is uhderftood, that the great- 

 er quantities of rain that fall in the winter, muft 

 occafion more Winds than in fummer, there being a 

 proportionable quantity of vapours condenfed; and 

 hkewilCj^- v ■■ ••.*'. '^:- - ■ ' *.■; ^ ; 



^"^:'. If the air be fviddcnly condenfed in any place, its 

 •. fpring will be fiiddenly diminiflied \ heixce, if this di- 

 minution be great enough toafFect the barometer^'ihbre 

 '^" will be a Wind blow'thrdugR'the condenfed air. '^' ■ 

 ■ ^. 'But fince it cannot be fuddenly condenfed, unlcfs 

 it has before been much rarefied, there will a Wind 

 ■'-' blow through the air as it dooTs,' after it is, violently 



^^ heated. - ;; vV " " / 'v . '' ^,'' '" 



6. In like manner if air be fuddenly rarefied, its fpring 

 is fuddenly increafed \ wherefore it will flow throdgli 

 the contiguous air, not afled on by the rarefying 

 '- force.-— A Wind therefore will blow out of a pTac^ in 



which the air is fuddenly rarefied ; and on this prin- 

 — ;ciple it is, in airprobabilityV'thl[V J^gv^ t^rui- - 



^7. Moft caves are fodnd to emit Wind, either" m'5re 

 ' "^or lefs. — -Since the fun's power in rarefying the air is 

 -notorious, it muft ncceffarily have a great influence 



on the generation of Winds.' p;;* -' . ^^ 'j^^-y^ 



^ The rifing and changing oftlie Wind is Jetermined 



experimentallyi' by means 'of '.Veathfer-cbcks placed 



''on the tops of houfes, &c.-i^But thefe only indicate 



• what pafl/es about their own height, or near the fur- 



■' face of the earth; Wolfius aflAiring'us, from obfer- 



■ vations of feveral years, that the higher Winds^which 



' drive the clouds, are" difi'erent' from the lower ones, 



whichmove the weather-cocks. ^:*V'^.. ^" ^*"-?'^''"^. 



5 



Winds 



». 



toward the equator"; becaufe the former are more 



fubject to rain. > - ;- : •-.-; ■ .„ . . 



6. Why there is more rain and Wind in the winter 

 than in the fummer, when the heat of the fun is in the 

 former more weak and languid, by which it is inca- 

 pable of raifing any great quantity of vapour to pro- 

 duce that rain and Wind. . ■ ■ . . * - 



7. Why they have more rain and Wind toward the 

 poles and about the equator, although the latter is a 

 part of the world where the fun makes the greateft 



"-Dr. Derham obferves, upon comparino: leveral feries 



■■^ of obfervatlons made of the Winds in d 



■viz. England, Ireland, Switzerland,^ Italy, France, 



'-■ New England, &c. that the Winds in 'thofe feveral 

 places feldom agree ; but when' they do, "if ji' com- 

 monly when they are ftrong, and of long continuance 

 in the fame quarter ; and more, he thinks, Tn the 



'"^hortTierly'andeafterly, than in anv other points^.-^— Al- 

 fo, that a ftrong Wind in one place is oftentimes a 



■ weak one in another; or 'moderate, according 'as the 

 places are hearer or more remote. - 



1 1-* 





of the force and Velocity of Wind, 





1, 



] - 



-tt -- 



^ , aporation. * ■ > 

 The induftry of fome late writers have brought the 

 theory and produftion, and motion of the Winds, to 

 fomewhat of mathematical demonftration, we fliall 

 here give it to the reader in that form. ;* * 



i' 



Wind being only air in motion, and air a fluid fub- 

 jeft to the laws of other fluids, its force may'be 

 brought to a precife computation : thus ; ; ',''-' ^ 

 The ratio of the fpecific gravity of any other 'fluid 



. to that of the air, together with the fpace that fluid, 

 impelled by the preffure of the air, nioyes in any 



' given time, beins; eiven ; we can det(jrmlne the fpace 



/ 



'/ 



I 



