Chap, li.] Periodical trade Winds. 455 



towards the eaft, arid confequently produces a weftern 

 wind. 



But thefe effects are much more perceptible in 

 countries near the tropics than with us. For when the 

 fun approaches the tropic of Cancer, the foil of-Perfia, 

 Bengal, China, and the adjoining countries, becomes 

 fo much more heated than the fea to the fouthward of 

 thofe countries, that the current of the general trade 

 wind is interrupted, fo as to blow, at that fcafon, from 

 the fouth to the north, contrary to what it wouid do if 

 no land was there. But as the high mountains of 

 Africa, during all the year, are extremely cold, the low 

 countries of India, to the eaftward of it, become hotter 

 than Africa in iutnmer, and the air is naturajjy drawn 

 thence to the eaftward. From the fame caufe it fol- 

 lows, that the trade wind, in the Indian Ocean, from 

 April till October, blows in a north- eaft direction, 

 contrary to that of the general trade wind, in open feas, 

 in the fame latitude j but whenxhe fun retires towards 

 the tropic of Capricorn, thefe northern parts' become 

 cooler, and the general trade wind afllimes its natural 

 direction. 



Having given the mod obvicus caufes of the pe- 

 riodical monfoons in the Indian feas, it is necefiary to 

 obfervr, that no monfoon takes place to the fouth- 

 ward of the equator, except in that part of the ocean 

 adjoining to New Holland. There the fame caufes 

 concur to produce a monfoon as in the northern tro- 

 pic, and fimilar appearances take place. From Octo- 

 ber till April the monfoon fets in from the N. W. to 

 S. E. oppofite to the general courfe of the trade wind 

 on the other fide of the line j and here aifo the general 

 trade wind re fumes its ufual courfe during the other 

 months, which conftitute the winter fcafon in thefe 

 regions. It may not be improper to conclude this 

 G g 4 account 



