286 THE CHEMISTRY OF CREATION. 



undimmed by a cloud. Such a phenomenon 

 does not appear to have been ever noticed in 

 our own country ; but an observer who was at 

 Constantinople relates that he was out in a 

 pretty heavy shower which lasted for ten mi- 

 nutes, while the sky was serene and cloudless ! 

 In the island of Mauritius this phenomenon is 

 very common in the seasons when the south- 

 east winds blow. About evening time, while the 

 weather is most beautiful, and the stars shine 

 with the utmost brilliancy of lustre, a very fine 

 rain occasionally descends ; and Sir J. C. Eoss 

 relates that in the South Atlantic, it rained upon 

 one occasion for upwards of an hour, while the 

 sky was altogether free from clouds ! 



The wet season of tropical countries, a season 

 of almost unintermittent rain of the heaviest 

 kind, is a very remarkable and regular pheno- 

 menon ; but is explicable on simple principles. 

 At such periods the great atmospheric currents, 

 which in these countries are of great steadi- 

 ness and duration, receive an altered direction, 

 and the condensation of an enormous volume 

 of watery vapour, and its precipitation in the 

 form of rain, take place as a result of the accom- 

 panying intermixture of hot and cold streams of 

 air. 



Important chemical functions are discharged 

 by rain. There are regions where, for five or six 



