364 On Rain, Evaporation, Se 
With respect to the deficiency of 7 inches,. 
there are three causes to be assigned for it, which 
appear to me fully sufficient, without having re- 
course to any source but that of rain for the 
supply of the earth in general. 
ast, In the account of the rain that passed 
through the earth in our evaporating vessel, 
there are a few monthly. products marked,+ 
those were occasioned by the bottle that re- 
ceived the water through the pipe being found 
with the water running over ; this loss was placed 
to the account of evaporation; it could not be 
much, as the water was taken several times in a 
month, but possibly might amount to one inch 
in the year. 
ad. The rain at Manchester, being 334 inches 
annually, exceeds the medium of g1 inches ; and 
consequently, according to the preceding obser~ 
vations, the evaporation ought to exceed the 
medium. 
gd. But the principal cause of the excess 
in our account of evaporation, I conceive to be 
the prevention of the water running off from the 
surface of the earth at the top, by having the 
earth below the level of the upper pipe: It has 
been seen, that when the earth was above that 
level, a great part of the water came off that way, 
by which the surface was sooner dried: whereas 
by forcing all the water to sink through the 
