DISTURBANCES AT BOMBAY. 137 



an average, continues in operation until four 

 o'clock in the afternoon, during the whole of 

 which time the barometer falls, and the sea breeze 

 blows with increasing force. At four o'clock 

 cloud ceases to form, — the barometer then ceases 

 to fall, and soon begins to rise, whilst the sea 

 breeze becomes weaker, until about ten o'clock 

 in the evening, when the barometer attains its 

 greatest evening height, and the sea breeze ceases 

 to blow. 



During the six hours last named, from four to 

 ten o'clock, that the atmosphere over the land 

 becomes heavier than it had previously been, is 

 indicated both by the rise of the barometer and 

 the decline of the sea breeze. But it is here 

 contended that these results are produced, not 

 merely through that reduction of temperature 

 which is marked by the fall of the thermometer, 

 but in addition, and principally, through the 

 cooling of a large mass of the atmosphere by 

 cloud evaporation. From ten in the morning to 

 four in the afternoon, a portion of the vapour 

 over the land had been condensed and formed 

 into cloud ; and the heat liberated by that con- 

 densation rendered the land atmosphere lighter 

 at the time : but now, from four to ten at night, 



