254 Dr ' dobson’s Obfervatiom on 
4. On comparing the depth of rain with the annual 
evaporation of this part of Lancafhire we find, that more 
falls in rain than is raifed in vapour, even though the 
whole were a furface of water; for the rain is to the 
evaporation as 37.43 inches to 36.78 inches: and we 
farther find, that the quantity exhaled from the furface 
of the earth is little more than a fixth part of what de- 
fcends in rain ; we muft therefore have very large fup- 
plies from other regions, from the furrounding fea, and 
from the ocean of warmer climates. Hence we fee, why 
our South and South -weft winds are fo often accompa- 
nied with rain ; for as the air fweeps along the warmer 
latitudes, it involves a large proportion of moifture, 
which is conftantly and copioufly exhaling from the 
ocean ; and this moifture being retained in a ftate of fo- 
lution till it reaches the colder climates, is then either 
collected in clouds or immediately precipitated in rain, 
according to the different conditions of the atmofphere. 
Thefe foreign fupplies, however, are uniformly re- 
ftored to the fources from which they were derived : for 
that proportion of rain which rifes not in vapour, after 
moiftening and refrefhing the earth, forms fprings, 
"brooks, and rivers, and is thus perpetually returning to 
the ocean whence it was taken; fo truly philofophical are 
the words of the preacher when fpeaking of this vaft 
circulation ■: 
