METEOROLOGY. 



247 



torrents of rain, which, in some instances, must descend almost in 

 a continuous sheet, as when 9 or 10 inches 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 quan- 

 tities 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 atmosphere the mighty volumes of water requisite for the 

 supply of our lakes and rivers. 



One might have supposed that the greatest fall of rain would 

 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, in the vale of Borrowdale, which affords the principal 

 supply of water to the river Derwent, 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 feet, and then diminishes 

 above that limit : — this may perhaps be accounted for, by con- 

 cluding, that as the clouds are seldom a mile high, (or little more 

 than one and a half times the height of Scawfell,) 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 unfrequently, its 

 upper surface also. Now, when this is the case, the guages on 

 Scawfell, Great Gable, &c, will receive no rain at all, when it is 

 descending abundantly in the valleys beneath. The lowness of the 

 rain-cloud at this season is probably the principal cause of the 

 small quantity of rain in proportion to the valley during the 

 winter as compared with the summer mouths. 



The winds in this part of our island are chiefly from the west 

 and south-west, and these are loaded with moisture evaporated 



