[ 3S6 ] 
’But if the legs are of unequal bores, neither of thefe will 
give the true height of the column of water which the 
wind fuflained. But the true height may be obtained by 
the following 
Suppofe that after a gale of wind, which had blown the 
water in one of the tubes from a to b (fig. 3.), forcing it at 
the fame time through the other tube out at e, the fur- 
face of the water fliould be found ftanding at fome level 
DG, and it were required to know what was the height of 
the column ef or ae, which the wind fuflained. In order 
to obtain which, it is only neceffary to find the height of 
the columns db or gf, which are conflantly equal to each 
other : for either of thefe added to one of the equal co- 
lumns AD, EG, will give the true height of the column 
vof water which the wind fuflained. 
c A s E I. 
Let the diameters ac, eh, of the tubes be refpe6lively 
reprefented by c, and let ad or eg, and a=db or gf. 
Then it is evident, that the column db is to the column 
EG as c^x to d^a. But thefe columns are equal. There- 
fore, c^x-d'-a^ and confequently, x--^' 
C 
EXAMPLE. 
If the diameters ac, eh, be refpedlively 10 and i, and 
AD or eg= 3,96 inches, x will be=:,o396 of an inch. 
For d^'a—i x 3,96 = 3,96, which divided by t““= 100, gives 
^^=,0396. 
case 
