370 THE PHYSICAL GEOGRAPHY OF THE SEA. 



monsoons generally. The mean height of the barometer during 

 the three months of June, July, and August, when the southwest 

 monsoons are at their height, is, 



For Calcutta 29.55 inches. 



" Bombay .' 29.65 " 



Madras 29.73 



(( 



The line S.W. represents the mean barometric declivity of the 

 southwest monsoons at their height, and indicates that at their 

 northern edge, supposed to be the parallel of 80° north, the ba- 

 rometer stands at about 29.45 inches. This barometric declivity 

 indicates that the southwest are stronger than the northeast mon- 

 soons, and observation shows that they are.* 



692. These are the winds — the southwest monsoons — which. 

 The summer rains of comiug from the sca. Carry into the interior rains 

 cherraponjie. ^^^ ^-^Q great watcr-shcd of India. They bear with 

 them an immense volume of vapor, as is shown by the rivers, 

 and confirmed by the rain-fall of Cherraponjie, and at 126 other 

 stations. Cherraponjie is 4500 feet above the sea level. It reach- 

 es quite up to the cloud region, and receives a precipitation of 

 537J inches during the southwest monsoon, from May to Au- 

 gust inclusive. Col. Sykes reported to the British Association, 

 at its meeting in 1852, the rain-fall at these 127 places, which are 

 between the parallels of 20° and 34° in India. According to this 

 report, the southwest monsoons pour down during the three sum- 

 mer months upon this water-shed 29f inches of rain. The latent 

 heat that is liberated during the condensation of the vapor for all 

 this rain expands the air, causing it to boil over, flow off, and leave 

 a low barometer — a diminished atmospheric pressure throughout 

 all the region south of the Himalaya. 



693. As long ago as 1831, Dove maintained that the southwest 

 Dovo and the mon- Hionsoou was the southcast tradc-wiud rushing for- 

 ^'"^^^- ward to fill the vacant places over the northern 

 deserts. Dov^ admits the proofs of this to be indirect, and ac- 

 knowledges the difficulty of finding out and demonstrating the 

 problem. 



694. But any navigator who, during the summer months, has 

 The southeast trades occasiou to travcrsc the Indian Ocean from north 



passing into southwest , p j xi i. -x " mi x J 



monsoons. to souto, may find that it is so. The outward- 



* Dr. Buist. 



