352 On Rain, Evaporation, 8c. 
shall have 36 inches of water at a medium an- 
nually on the surface of the earth in England and 
Wales, reckoning 31 for rain and 5 for dew 
Accordingto Guthrie, the area of England and 
Wales is 46.450 square miles. This reduced to 
square feet, gives 1.378.586.880.000: which, 
multiplied by 9 feet the annual depth of rain 
and dew, gives 4.-135-760.690.000. cubic feet 
of water==153.176.320.000 cubic yards, or 28 
cubic miles—115 thousand millions of tons in 
weight, nearly.—We must now consider how 
this enormous quantity of water is disposed of. 
There are two principal ways by which the 
water derived from rain is carried off again : 
One part of it runs off immediately into rivulets, 
~ or sinks into the earth a small way, breaks out 
again in lower ground in the form of springs, 
thence makes its way to some river, by which 
it is conveyed into the sea—another part is_ 
raised: into the atmosphere by evaporation, We 
take no notice here of the decomposition of water 
by vegetables; because it is presumed that in 
the course of nature the principles. are combined 
and water formed again. 
| 
by pouring cold spring water into a dry and clean glass, 
and marking what degree of cold is sufficient to produce 
a dew onthe outside of the glass; at other times frigorifie 
saline solutions may be used, 
