OF THE EARTH^S ROTATION ON WINDS. 253 



parts of the earth's surface ; and the other, that the un- 

 equal rotatory velocity of different latitudes palpably modify 

 and disturb the course of the winds. The former of these 

 causes has been erroneously said to produce the monsoons 

 of the Indian Ocean. This I have elsewhere shown to be 

 an error, more particularly as regards the south-west 

 monsoon. But the second assumption, which we are more 

 specially considering, deserves further examination in re- 

 ference to this part of the world. The north-west or 

 winter monsoon of the Indian Ocean is first found over 

 the ocean near to Arabia and Africa, moving towards 

 the equator, and according to the laws of retardation, as 

 laid down by modern meteorologists, it ought to become a 

 north-east trade- wind blowing to the heated surfaces of 

 Africa. It does not, however, do so ; but from the mouth 

 of the Red Sea and the Persian Gulf, near the northern 

 tropic, it goes southward and eastwardj passing near 

 Hindostan, to the island of Ceylon; then turning more 

 decidedly eastward, it passes forward to the equator, and 

 terminates at the islands of Sumatra and Java, where 

 heavy rains are falling. So that this wind passes through 

 23° of latitude over a sea cool compared with burning 

 Africa, and in a direction the opposite to that in which 

 Africa is situated, and at the same time traverses 40° of 

 longitude with greater rapidity than the surface of the globe 

 that sustains it ! Instead of being left behind by the ro- 

 tating surface, it travels eastward faster than that surface, 

 moving steadily forward with increasing velocity to cloud- 

 covered islands which are cooled and drenched by heavy 

 rains. 



But this is not the only part of the Indian Ocean where 

 wind travels faster than the surface of the globe. When 

 the sun has fully heated the southern hemisphere, a wind, 

 called the petty monsoon, is found blowing eastward from 

 the neighbourhood of Madagascar across the Indian Ocean 



