XMleteoroloss* 345 



are precipitated in forty-eight hours. When we reflect that 

 a warm moist current, perhaps only three or four degrees 

 above the point of saturation, in coming in contact with the 

 mountain-ridges, probably meets with a stratum of air ten 

 or fifteen degrees lower than its own inherent temperature, 

 we shall cease to marvel that such quantities as 4, 5, or even 

 6 inches of water should be deposited in these localities in 

 the course of a few hours. The mountains are, in fact, 

 huge natural condensers, destined to force from the at- 

 mosphere the mighty volumes of water requisite for the 

 supply of our lakes and rivers. 



One might have supposed that the greatest fall of rain 

 w^ould have been at Wastdale Head, as it is surrounded 

 by the highest mountains, and the valley opens out fairly to 

 the S.W. But the maximum quantity is not found to obtain 

 where theory would indicate, — the vale of Borrowdale, 

 which affords the principal supply of water to the river Der- 

 went, and the extensive and picturesque lakes of Derwent- 

 water and Bassenthwaite. To refer again to the fact that 

 among the mountains the quantity of rain increases to the 

 altitude of 2,000, and then diminishes above that limit : — 

 this may perhaps be accounted for by concluding that, as 

 the clouds are seldom a mile high, (or Httle more than one 

 and a half times the height of Scafell), in our climate, in 

 winter, there can be no doubt that, during the winter months 

 especially, the under surface of the Nimbus or rain-cloud, 

 (the lowest except the Stratus), is far below the tops of our 

 highest mountains, and we may safely conclude, not un fre- 

 quently, its upper surface also. Now, when this is the case, 

 the guages on Scafell, Great Gable, &c., will receive no rain 

 at all, when it is descending abundantly in the valleys be- 

 neath. The lowness of the rain-cloud at this season is pro- 

 bably the principal cause of the small quantity of rain at 



