Ai 
C 
L 
K 
[ 264 ] 
BDF find the proportion between the 
G N denfity of the air, and that of 
the quickfilver, the obferved tem- 
perature being fuppofed to obtain 
uniformly throughout the whole 
atmofphere ; or at lead:, through- 
EHM out a great portion of it, on all 
fides of B. 
Suppofe it done ; and that the 
denfity of the air, at the time 
P and place of obfervation, is to 
■ ■ ■ the denfity of the quickfilver 
R — — - * in the barometer, as the right 
S — - line CD to EF. Now the 
temperature of the air being gi- 
ven, the fubtangent of the lo- 
giftic correfponding to the gi- 
ven temperature is given (by prob. 3d). Let GH be 
equal to that fubtangent; and iet KL be the perpen- 
dicular height of the mercurial column fupported 
in the barometer at A, the earth’s furface, at the 
time of obfervation at B. Now fince EF is to CD 
as the denfity of quickfilver, in the barometer, to 
the denfity of the air at B, and CD is the per- 
pendicular height of the column of quickfilver 
fuftained in the Torricellian tube at the place B, at 
the time of obfervation, it is evident, thatEF is the 
perpendicular height of a column of an inelaftic 
fluid, of the fame denfity with the air at B, which, 
if it were urged with an accelerative force through 
its whole length every where equal to that of gra- 
vity at B, would, by its compreffive force, fuftain the 
mercurial column CD : for the accelerative forces 
fuppofed 
