

DEW 



naliCptaphyllosbaccifera. C. B. P. 322. Seven-leaved 



I'ulb-karing ToolkivorL 

 3- Dentaria {Enneapbjllos) foliis tcrnis tcrnatis. Lin. 

 Sp. Plant. 653. Toolbzvort ^J)ith three-leaved trifoliate 

 leaves. Dcntaria triphyllos. C. B. P. 322. Three-leaved 

 Toothivort. 



The firft Ibrt rifes with aftrong flalk afoot and a half 

 high, garninicd with a leaf at each joint, compofcd 

 of five lobes, which are four inches long, and near 

 two broad in the widcft part, ending in acute points, 

 deeply fawed on their edges; thefe are fmooth, and 

 Hand on long foot-ftalks ; the flowers grow in loofe 

 fpikes at the top of the ftalks ; they are fmall, of a 

 blufh colour, and fuccceded by long taper pods filled 



with fmall roundifh feeds. 



It grows in the 



fhady 



woods in the fouth of France and Italy. 

 The fecond fort rifes with flender ftalks about a foot 

 high ; the leaves at the bottom have feven lobes, 

 thofe a little above five, others but three, and at the 

 upper part of the ftalk they are fingle : the flowers 

 grow in clufters at the top of the ftalk •, thcfe have 

 four obtufe purple petals, and are fuccceded by taper 

 pods filled Vv'ith roundifli feeds. 



The third fort rifes with an upright ftalk a foot high •, 

 the leaves are compofcd of nine lobes, three growing 

 together, fo that one leaf has three times three ; the 

 flowers grow in fmall bunches on the top of the ftalks, 

 and are fuccceded by fmall taper pods filled with 



ronndifli feeds. 

 ^ Thcfe plants grow on the mountains in Italy, and in 

 ^ the woods of Auftria. The fecond fort is found wild 

 in fome parts of England, but pardcularly near Hare- 

 field, in moift fhady woods, and is feldom preferved 

 in gardens : this produces bulbs on the fide of the 

 ftalks, where the leaves are" fet on, which, if planted, 

 will grow and produce plants. Thefe plants are pro- 

 pagated by feeds, or parting their roots •, the feeds 

 fhould be fown in autumn, foori* after they are ripe, 



■ in a light fandy foil and a ftiady fituation : in the 

 fpring the plants may be taken up where they grow 

 too clofe, and tranfplanted out in the like foil and fi- 

 tuation; where, after they have taken root, they 



^f- will require no farther care, but to keep them clear 

 j. from weeds: the fecond year they will produce flowers, 



- and.fometimes perfeft their feeds. 



. The beft time to tranfplant the roots is in October, 

 .- when they fliould be planted in a moift foil and a 

 . ftiady fituation ; for they will not live in a dry foil, or 



when they are expofed to the fun. 

 DEW is by fome defined to be a meteor bred of a 

 thin cold vapour, or compofed of the fteams and 

 vapours of the earth; which, being exhaled by the 

 heat of the fun, and kept fufpended during his pre- 

 fence, do, upon his abfence, convene into drops, and 

 , then fall down unto the earth again. 

 Others define it, a thin, light, infenfible mift or rain, 

 falling while the fun is below the horizon. : 

 The origin and matter of dews are, without doubt, 

 .' from vapour and exhalations of the earth and water, 



- raifed by the warmth of the fun and earth, &c. 



. There being many vapours in the air, though riot 



' always vifibTe, hence it comes to pafs, that even in 



• clear weather great dews fall, efpecially in countries 



V where it ieldom rains ; for when it happens that the 



■ fcattered vapours are colledted and condenfed together, 

 ' and forced downwards, they muft needs fall, and be- 



-dew the plants and grafs. - > . 



The thin veficles, of which vapours confift, being 



once detached from their bodies, keep rifing in the 



air till they arrive at fuch a ftage as is of the fame 



fpecific gravity with thcmfelves, when their rife is 



flopped : nowj as it is the warmth or fire that dilates 



the parts of water, and forms thofe veficles that are 



fpecifically lighter than the air, and are capable of af- 



ccnding therein; fo when that heat declines, or is 



loft, as by the approach or contiguity of any colder 



body, t\\i^ veficles condcnfe, and become heavier and 

 dcfccnd, ..... 



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Therefore the fun warming the atmofphere in the 

 day;time, by the condnual influx of his ravs, the Va- 



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pours being once raifed, continue their progrcfs, not 

 meeting with any thing to increafe their gravity 

 till fuch time as diey are got far beyond the reach of 

 die reflected warmth of the earth in the mldtllc re- 

 gion of the atmofphere, and there condenle and form 

 clouds. 



Though fome fay, it is difputable whether dews ever 

 congregate fo as to form clouds, as they are only 

 elevated by the fun ; fo that when that power is gone, 

 as it is after the fetting of the fun, they immediately 

 defccnd ; and this is more obfcrvable in very warm 

 weather, and very hot climates. 

 The time for the falling of the dew is either before 

 fun-rifing, or after fun-fet ; that it may regularly fall 

 at fuch times, it is necefl^ary for the air to be calm, 

 for windy or ftormy weather hinders it ; but when it 

 is calm weather, and gentle breezes are felt from the ' 

 weft about the fetting, and from the eaft about the 

 rifing of the fun, it is probable, that by moderately 

 cooling the air, they coUeft the vapours and precipi- 

 tate tht^m ; and becaufe the morning breezes are more 

 general than the evening ones, for this reafon the 

 evening dews fall only here and there, but thofe in 

 the morning feldom fail to be univerfal : or, as it 

 may be otherwife expreflcd, when the fun is got be- 

 low the horizon, the atmofphere cools the vapours, 

 which have in the preteding day been raifed by the 

 warmth of the earth ; and die rays of the fun being 

 lodged there, as foon as they are got out of the air, 

 they begin to condenfe apace, and fpend their ftock 

 of heat and fire on the cold moift air that they pafs 

 through. 



_^ Hence it is, that dews are more copious in the fpring 

 tJi an other feaforis, there being a greater ftock of va- 



"' pour in readinefs, by reafon there has been but a fmall 

 expence thereof during the winter's cold and froll 



' than at other times. 



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i-_It,i.s^ found by experience, . that the dews are more 

 copious in hotter countries than in cold, as Pliny ob- 

 ferves'of the fummer nights in Africa, which he calh 

 Rofcid^ seftate noftes ; the reafon of which feems 

 to be this, that in the day-time the heat of the fun 

 raifes abundance of vapours out of the water; which 

 vapours are fo extremely rarefied by the fame heat, 

 that they are difperfed far and wide ; but the cool of 

 the night brings them together, and condenfes them 

 'to that degree, that they fall to the grouiid, but not 

 in fuch large drops as rain does ; but in colder coun- 

 tries, where there are frequent rains, and the vapours 

 are lefs rarefied, moft of them come down in rain, 

 and but a fmall part turns to dew : befides, in Africa 

 there is a great difference between the heat of the day 

 and night, particularly in fummer; for their nights 

 are long, and very cold ; whereas in northern coun- 

 tries they are little colder than the day, and much 



••■c -, i 



fliorter than in places nearer the line. 

 Pliny likewife relates of Egypt, that it abounds in 

 dews throughout all the heat of fummer ; for the air 

 being there too hot to conftipate the vapours in the 

 day-time, they never gather into clouds, and for that 

 reafon they have no rain. But it is known, in climates 



. where the days are exceflive hot, the nights' are re- 

 markably cold, fo that the vapours that are raifed 

 after fun-fet are readily condenfed into dews: or, 

 perhaps notable coldnefs may be rather the effeft than 



, the caufe of the quantity of dews ; for much vapour 

 being raifed by the great heat of the earth, and the 

 ftock of fire being Ipent on it in the day-time, the 

 influx of fuch a great quantity of moifture mull greatly 



chill the air. . . '- , , : >:.i ' - 



The difference between dew and rain feems to be 



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only this, that dew falls at fome particular dmes as 

 aforefaid, and in very fmall drops, fo as to be fecn 

 when. down, but fcarce perceivable while it is falling; 

 whereas rain falls at any time, and in grofler drops. 

 The reverend Dr. Hales, in his Treatife of Vegetable 

 Statics, tells us. That in order to find out the quan- 

 tity of dew that fell in the night on the 15th pi Au- 

 ■ guft, 7 p. m. he took two glazed earthen pans, which 

 were three inches deep, and twelve inches diaoiercr 



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