ON THE PHYSICAL GEOGRAPHY OF 



fused, was 0*824 inch. The mean weight of vapour contained 

 in a cubic foot of air was 3*69 grains avoird., and an ad- 

 ditional fraction of 0*67 grain was required to saturate the 

 same bulk of air, i.e., to exhaust its power of suspending 

 vapour at a certain temperature. Complete saturation being 

 counted unity, the mean humidity of the atmosphere was 

 0*852. The average quantity of vapour mingled with the air 

 would have produced a precipitation of 4*48 inches of rain, 

 had it been all deposited at once upon the earth. The mean 

 annual fall of rain was 28*05 inches, and the number of rainy 

 days was 178. The greatest fall was 31*41 inches, in 1847 ; 

 and the least 21*46 inches, in 1850. The amount of cloud 

 will be represented by 6*7 of the whole sky — ten being com- 

 plete obscuration: the largest mean amount was 7*2, in 

 1850; and the smallest 6*3, in 1849. 



The influence of the sea in moderating the ordinary extremes 

 of temperature must not be forgotten. The open coast too, 

 exerts its power upon the Flora, for where bold and rugged 

 rocks present a barrier to the waves, the wind carries the 

 spray inland, to the destruction of certain plants and trees 

 artificially planted, and to the prevention of the natural growth 

 of others. 



Liverpool, when considered in comparison with the more 

 inland localities, exhibits a much less variable and more limited 

 range of temperature. At Warrington, distant inland only 

 eighteen miles from Liverpool, the thermometer has been ob- 

 served as low as 13° Fahr., whilst at Derby it has sunk to 1° 

 below zero. The climate also is milder. It appears from the 

 Manchester meteorological tables that Liverpool has an average 

 annual superiority in this respect over Crumpsall of about 2°; 

 and the difference is still more marked when compared with 

 other places at no great distance inland. 



In conclusion it may be observed, that a local Flora is sub- 

 ject to changes slow but certain. Habitats arc forsaken under 

 the influence of cultivation and the increase of buildings and 

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