Meteorological Obfervations. 599 
‘aft-mentioned gentleman. I therefore fet about 
the inveftigation of Mr. Dalton’s theorem, and 
from: the fame principles obtained an expreffion 
which was only zz of his. But diftrufting my 
own inveftigation,- when contrafted -with: the 
‘known abilities of Mr. Dalton. as a mathe- 
-matieian, I wrote to my friend Mr. Dawfon, 
of Sedbergh, defiring his opinion on the fub- 
jed, and his anfwer is as follows —*‘ There is 
eertainly a miftake in Mr. Dalton’s. theorem 
“for determining the height of water fallen upon 
ta:given horizontal plane, as you will eafily fee 
from what follows. 
‘* Befides the fymbols he makes ufe of (viz. 
a= the area of the. {perture of the, fynnel, W 
the weight of i cubic foot of water, and w the 
weight of the mye canal in pounds), put 
x ==the depth of the water fallen in inches, 
then ax= the’ number of folid inches in the 
gage, and bet aufe the weight varies as the 
number of folid inches, ... W:w:: 1728: ax, 
1728 w 
OH aba 
depth. required. —Mr. Dalton’s expreffion is juft 
twelve times the above. You will eafily ob- 
ferve that the 1728 is the number of cubic 
inches in a folid foot, of which /” == the 
weight in avoirdupoife pounds,” 
The eafieft way of finding the perpendicular 
height of water fallen, is to meafure the water 
caught 
and an X W = 1728 Xv, orx= 
