120 SEASIDE DIVINITY. 



such as do not appear to be subject to any gene- 

 ral rule. All winds or aerial currents may be 

 said to be caused by something which acts either 

 continuously or at intervals in disturbing the 

 equilibrium of the atmosphere. 



Of this the tropical winds afford the most 

 remarkable instances. The trade-winds of the 

 Atlantic are occasioned by the heat of the sun, 

 which, rarefying the air over the African continent, 

 causes it to rise upwards, when its place is im- 

 mediately supplied by currents of colder air 

 blowing from the north and south. In the 

 Indian Ocean likewise, a similar phenomenon 

 takes place ; the air over the vast plains of tropi- 

 cal India becomes heated, and a current blowing 

 from the south to occupy the place of the heated 

 atmosphere causes the periodical winds known as 

 the monsoons. The sea and land breezes which 

 occur during the morning and night in the tropics 

 originate in a similar cause. The sun heats the 

 land, and consequently the air over its surface, 

 which ascending causes a breeze from the cooler 

 atmosphere over the ocean to blow towards the 

 land ; but at night, when the land and the air 

 over it have cooled down after sunset, the wind 

 blows from shore to supply the place of the 

 warmer air which then ascends 'from the surface 

 of the sea. 



The winds which prevail on the coasts of 

 Britain are extremely variable, and can hardly 

 be reduced to anything like system. But there 

 can be no doubt that they are occasioned by heat 



