208 Irifluence of the Phjsibal Character 



very dissimilar to that which marks the era of the later Coal 

 formation would flourish luxuriantly, affording sustenanoe to 

 tribes of animals suited to such conditions of life. 



It is far from my present purpose to enter largely into this 

 branch of the subject; it is only necessary to show how 

 materially configuration regulates the intensity of heat and 

 cold ; how a chain of lofty hills may serve as reservoirs of con- 

 gealed waters, whence rivers are supplied unceasingly ; how 

 low level plains, by favouring evaporation, and yet preventing 

 the formation of rainclouds over their surface, either become 

 arid and desolate wastes, or swampy jungles. This is not only 

 true of continents and large islands, but in lesser proportion is 

 known to influence districts of small area. A lofty hill some- 

 times makes a perceptible difference in the rainfall in its 

 neighbourhood ; a plain of a few miles in extent is sufficient 

 to give a distinctive character to the climate within its limits. 

 A difference in the superficial features of a country will not, 

 however, always explain vicissitudes of climate over limited 

 areas. The rainfall, more especially, is largely affected by the 

 direction of the winds. I am anxious to show the superiority 

 of not one particular cause, but rather to recognise them all. 

 Perhaps the best ai'gument I can use is to refer briefly to the 

 almost inexplicable variations of the rainfall in places very 

 near to each other. 



Instances of Variations in the Rainfall, — The mean fall of 

 rain for the whole of England is stated to be thirty-six inches, 

 but near London there is a fall of twenty-three inches, and in 

 Cumberland sixty.* The unequal fall of rain in Scotland is 

 also remarkable ; the average in Glasgow is rather more than 

 twenty-nine inches, in Edinburgh it is twenty-three; and 

 this within a distance of forty miles ! In the south-west of 

 Ireland the rainfall is forty-two inches, in Armagh it is about 

 twenty-two. 



The inequalities of climate being so palpably influenced by 

 such a variety of causes, we ought to reject every calculation 

 that is not based on actual observations within the locality, 

 to whieh such observations have reference. 



The Mean Annual Temperature also presents great differ- 

 ences in different localities, and in countries within the same 

 parallels of latitude. As an instance of this I may mention 

 the mean temperature of Switzerland, viz., 47°, which 



* Sir Charles Lyell mentions the following variations : — " At Whitehaven, in 

 Cumberland, there fell, in 1849, 32 inches ^ while the quantity of rain in Bor- 

 rowdale, near Keswick, (only 15 miles to the westward,) was no less than 142 



