THE MONSOONS. 255 



new aerial masses flow without cessation from the Indian Ocean to 

 the countries on the north. According to Dove, the trade-wind of 

 the south-east, carried away by this general displacement of the air, 

 would itself cross the equator, enter into the northern hemisphere, and 

 transform itself gradually into a monsoon from the south-west, 

 because of the great speed it acquires at the equator. Still it is 

 not probable that it is so, for the monsoon has not the same vertical 

 height as the trade-winds, and its direction is not uniformly from 

 south-west to north-east, as on the coasts of Malabar ; in the valley 

 of Scinde and in that of the Irawaddy it is directly south ; at the ex- 

 tremity of the Gulf of Bengal, at Siam, at the eastern angle of the 

 Asiatic continent, its direction is from south-east to north-west, per- 

 pendicular to the coasts which attract the wind.* 



Saturated with the moisture which has evaporated from the great 

 cauldron of the Indian Ocean, the monsoon inundates the coasts of 

 Malabar with torrents of rain, deluges the shores of the transgan- 

 getic peninsula, and then strikes against the high mountains of the 

 Himalaya, and other chains, which border the plateaux of Central 

 Asia on the south, but it does not cross this barrier. By its clouds 

 charged with rain, which are rent by the escarpments of the inferior 

 peaks, we see clearly that the sea wind does not pass the altitude of 

 4950 to 8250 feet, and that above it another aerial stratum is mov- 

 ing in the heights. The movement which carries along this elevated 

 stratum is the same as that of the monsoon from the south-west ; but 

 we recognize by its long trains of cirri, from 16,500 to 25,500 feet 

 high, that great returning current, or counter trade-wind, that blows 

 at the same elevation above the Atlantic in the neighbourhood 

 of the Canaries. 



When the sun, in its course over the ecliptic, returns towards the 

 tropic of Capricorn, the centre of attraction is at the same time dis- 

 placed in a southerly direction. The monsoon of the south-west ceases 

 to tend towards the great peninsulas of Asia, the regular wind from 

 the north-east recommences to blow, and the currents of attraction in 

 the southern hemisphere turn back towards the islands of Sunda and 

 Australia. Owing to this regular alternation, which was a surprise 

 to the ancient Greek navigator Hippalos, the mariners of the Indian 

 Ocean may count beforehand on a favourable wind which by turns 

 will drive their ship before it for the two passages, going and return- 

 ing ; and they have not to dread those prolonged calms which are the 

 bane of sailing vessels in the equatorial zone of the Atlantic and the 

 * Miiliry, Zeitschrift fur Meteorologie von Carl Jelinek, No. 21, 1867. 



