460 . Defcription of [Book V. 



off towards the poles, and, in the more contracted de- 

 grees of the higher latitudes, takes the courfe of the 

 weft trade winds, fo that could their afcent be pre- 

 vented through the whole circle of the zone, there 

 would be no more weft winds in thofe latitudes than in 

 any other. Very violent rains and cold, however, tend 

 to check the afcent of air out of this circle, rather 

 caufing it to defcend. dear clouds and vapour ge- 

 nerate cold and wet, while rain beats down the air j 

 and as -hefe prevenrthe rifing of the air out of the line, 

 ib they hinder its ufual progrefs from the tropics on both 

 fides ; hence the calms which ufually precede hur- 

 ricanes. Calms, in thefe tropical regions,. are caufcd 

 by the afcent of the air into the higher part of the at- 

 mofphere, inftead of its remaining near the line : the 

 accumulation of air above then becomes heavier by 

 the cold which it meets in thofe regions, and defcends 

 into the more rarefied region below. Thefe heavy 

 gales, therefore, will continue to defcend till the upper 

 regions are entirely exonerated *". 



In Mr. Beckford's hiftory of Jamaica there is a very 

 detailed and ftriking account of the dreadful hurricane 

 which defolated the iflands in the year 1780, but it is 

 too long for infertion as an extract, and in an abridged 

 ftate .the defcription would lofe its force. ' It is in the 

 rainy feafon (fays Mr. Adams) principally in the month 

 of Auguft, that they are afiaulted by hurricanes, which 

 deftroy at a ftroke the labours of many years, and 

 proftrate the mod exalted hopes of the planter, and 

 that, often when he thinks himfclf out of the reach of 

 fortune. It is a fudden and violent ftorm of wind, 

 rain, thunder, and lightning, attended with a furious 

 fwelling of the feas, and fomecimes with an earthquake; 



f Arr.cricap Phil. Tranf. vol. i. 



in 



