374 niYSICAL GEOGEAPHY OF THE SEA, AND ITS METEOROLOGY. 



tions of pressure. In the sea breeze, the land barometer would 

 be low and the sea high, and vice versa in the land breeze ; and 

 when the barometer was highest and when it was lowest it 

 would be calm at the barometric stations. 



699. The changing of the monsoons. — It is these calm bands or 

 " medial belts," as the crest and trough of the barometric wave 

 may be called, which, with their canopy of clouds, follow the 

 departing and herald the coming monsoon. They move to and 

 fro, uji and down the earth, like the sun in declination. As they 

 have a breadth of 200 or 300 miles, they occupy several days in 

 passing any given parallel, and while they overshadow it, then 

 the monsoons are dethroned. During the interregnum, which 

 lasts a week or two, the fiends of the storm hold their terrific 

 sway in these bands. The changing of the monsoons is marked 

 by storm and tempest. Becalmed in them, meanings are said 

 by seamen to be heard in the air — a sign of the coming storm — 

 a warning of impending danger to ship and crew. Then the 

 props and stays are taken away from the air, and the wind seems 

 ready to rush violently hither and thither, and whenever there 

 is from any cause a momentary disturbance of the equilibrium. 

 In such an atmosphere, the latent heat that is liberated by every 

 heavy rain-shower has power to brew a storm. Throughout ^the 

 monsoon region, the people know beforehand, almost to a day, 

 the coming of this interregnum, which they call the changing of 

 the monsoons, for the annual changing at the same place is very 

 regular. 



700. Sow the calm belt of Cancer is pushed to the north. — Theory, 

 therefore, points to a place in Northern India, which is near the 

 northern limits of the south-west monsoon, where the mean 

 height of the barometer during the rainy season (§ 691) is about 

 29.5 inches, the mean height at the equator being 29.92 inches. 

 Into this monsoon place of low barometer over the land the 

 wind rushes from the north-east as well as the south-west. The 

 place of high pressure towards the north from which it rushes is 

 imder the calm belt of Cancer. Hence this belt is also pushed 

 north, and made to occupy, in summer at least, the position over 

 land somewhat like that assigned to it on Plate VIII. In the 

 south-west monsoon the Malabar coast has its rainy season, so 

 that the air over the peninsula is permanently kept more or less 

 in a 3'arefied state, by the liberation of latent heat from vapour 

 as actual obsei-vations abundantly show. 



