BOOK III. CHAP. VII. 625 



denfe.air, caufeJ by the rain thu; fli;ikcn down, forjrjs a new wind 

 from the land, which feems to dii\c the clouds from ofl" the tnoiiii- 

 tain, to lea ; and when thtlc vapours arc entirely difen[>a;'cd from 

 tliefe high lands, the thunder generally ccafes ; they pafs filently 

 over the level country, where there is nothinjj to obflruS: their courfe. 

 Sometimes, when their eleftricity appears as it were exhaufted, the 

 fea-breeze returns again, checks iheir paflTige, and impels them back 

 to the mountains, where they either hold on their courfe pcaceablv, 

 or, meeting with new colledlions of other clouds, re-adl the fccne over 

 again, though with lefs turbulence than before. The expanfion, or 

 luift, remarked to encreafe after every fiafh, may probably be owinc 

 to a vacuum caufed by the lightning, into which the denfer particles 

 immediately rufh ; or an extreme rarefadion of watery vapour, caufed 

 by the fame aaent, which necellarily riles into a higher flation in the 

 atmofphere, for it always appears elevated far above thofe clouds, out 

 of which it has been formed. The atmofphere of thele thunder 

 clouds is perhaps colder and more denfethan the particles which coniii- 

 tute the fea-breeze; and therefore rcfifts and overcomes their motion 

 to a certain diftance. Hence, probably, the realon wh}', after thefe 

 clouds have p.iffed entirely away, if the fun fliould break out again, 

 with vigour enough to heat the air, over that trail of country where 

 the fiiowers had fallen two or three hours before, 'the breeze gra- 

 dually revives and ventilates it, but with a feebler cunxnt. 



Thunder and lightning often happen at the fc(ting-in of the Nbrtr.'s 

 in November, and at their breaking up in April or May; they feem 

 neceflary inftruments to bring about thofe periodical changes of the 

 ftated winds, which, but for tlieir operation, would not b.^ effetled 

 without a hurricane, or a fit of turbulent weather. 



Thunder-fqualis arc common to the months of June, Julv, Augufl, 

 Septetijber, particularly In the mountains. 



At the town of Kingfton there Is feldom any; the vaft mountains 

 behind it draw off the clouds on that fide, and being open towards 

 tlie lea, on the other, the vapours from land pnfs off at a great hei-'ht 

 above the town, free of Interruption. 



At Spanilh Town there is more of it, ihe Healthiliire-hiils to the 

 Southward giving fome impediment to the clouds ; fo that when, 

 they are checked at all by a fea-breeze. In their parage to the ocean, 

 they are either accumulated, or drove back againit the land wljid ; and 

 in either cafe, are fubjeft to be broken and diffufed in (ho%vers. 



It is curious to remark here the condant fteming attraction between 

 the mountains and the rain. Heavy fhowers are frequently leen to 

 traverfe the ridges, avoiding a nearer way acrofs the plain--, and lo 



Vol. II. 4 L creep 



