54 METEOROLOGY. 



which the atmosphere being incapable of supporting, 

 falls in .Ram. 



Under the idea that Rain is caused by the disturbance 

 of the electricity of the clouds, Sir Richard Phillips, many 

 years ago, published a plan for fertilizing barren districts 

 by erecting metallic rods on elevated spots, thus arrest- 

 ing the clouds and producing rain. It is well known that 

 more rain falls in mountainous countries than in plains ; 

 it is also surmised that the leaves of vegetables, particu- 

 larly of trees, have a tendency to attract the electricity 

 of the atmosphere, from the fact that woody countries re- 

 ceive most rain. Sir Richard attributes the sterility of 

 certain countries to the cutting down of trees, and con- 

 ceives that to this may be ascribed the present sterility 

 of the once fertile but now desert regions of Syria, 

 Chaldea, and Barbary ; and he ascribes the oases of the 

 desert to the circumstance of a few trees having been 

 accidentally suffered to grow in them. 



In our own country, as well as in others, most rain 

 falls in places near the sea-coast, so that while the mean 

 annual depth of rain at London is 23 inches, it is some- 

 what more than twice as much near the western coast. 

 A greater quantity of rain falls in most countries during 

 the summer months, than during the winter months, and 

 the mean annual quantity is greatest at or near the 

 equator, and diminishes towards the poles. In Grenada 

 the annual depth of rain has been found to be 126 inches, 

 when in England* it was 32 inches, and at Petersburg 

 16 inches. 



The whole of the vapours which are exhaled from the 

 surface of the earth are not formed into clouds : some- 

 times, through an imperfect condensation, they remain 

 suspended in the form of Fog or Mist ; sometimes, through 

 the coolness of the air, a more perfect condensation takes 

 place, and they fall in Dew. 



Dews are found to be more copious in clear than in 

 cloudy weather, also in spring than in any other season, 

 there being then more vapour than at any other time. 



* It is calculated that from 300 to 400 tuns of rain fall annually 

 on an average on every acre in England. 



