THE MEASUBEMENT OF RAIN. 13 



called Longdendale, running for several miles nearly due 

 west between hills which rise abruptly on each side to a 

 considerable height, reaching in some cases nearly 2000 

 feet above the level of the sea. 



The valley is hemmed in to the west by the high land at 

 Mottram, which, however, is not high enough to intercept 

 the clouds driven before the westerly winds. 



three first and three last months of the year. Moreover, Dr. Dalton 

 affirms that the clouds are seldom a mile high (or little more than one and 

 a half times the height of Sea Fell), in our climate, in winter. Now the 

 Doctor here probably alludes to, or at least includes, the most elevated 

 clouds, such as the Cirri, and some variety of the Cirrostratus. But there 

 can be no doubt, that between the months of November and March the 

 under surface of the Nimbus or raiu cloud (the lowest except the Stratus) 

 is far below the tops of our highest mountains, and, I have reason to 

 believe, not imfrequently its upper surface also ; when this is the case, 

 the gauges on Sea Fell, Gabel, &c., will receive no rain at all, when it is 

 descending abimdantly in the valleys beneath. The lowness of the rain- 

 cloud at this season, is, I apprehend, the principal cause of the small 

 quantity of rain in proportion to the valley, during the winter as com- 

 pared with the summer months." 



He also observes as to the value of the experiments, that " they have 

 already shown us that at least sixty inches more rain is deposited in Eng- 

 land than we were previously aware of: — that one hundred and fifty 

 inches sometimes descends in the Lake districts in a year, — more than falls 

 in most parts of the Tropics with which we are acquainted, and sufficient 

 to drown standing two of the tallest men in Great Britain, one on the 

 top of the other. They have further informed us, that six and a half per- 

 pendicular inches of water is sometimes precipitated from the atmosphere 

 in twenty-four hours, and ten inches in forty-eight hours ; a quantity 

 which would be thought large for any two consecutive months in most 

 parts of England. We have further ascertained that the almost incredible 

 depth of thirty inches occasionally descends in a single month — a fall 

 nearly equal to the calculated yearly average for all other parts of Eng- 

 land. The experiments have, in short, enabled us to collect a number of 

 new and curious facts, bearing on the quantity and very unequal distribu- 

 tion of rain in this island. We have also ascertained with a high degree 

 of probability, the law of the gradation in the amount of rain, at various 

 intermediate points, between the valleys and the tops of the highest moun- 

 tains. 



