Temperature of Merry in in a Siphon Resonate. 263 
b” —b = prait Mee b) 
a ut wile Mt 
a” —a— vila —a) 
whichis the same as (32). 
In like manner, substituting in (31,) and resolving for (¢’ —1), 
we have 
; (35) 
' (t’—t) [a’—a el — b)] 
t=t+_ (36. ) 
dab" b)+(¢t’— tea” —a’— — Fi (0” —b/)] 
Neglecting the fourth term in the denominator from its minute- 
hess, we have 
Unf r 
=t+ = [a’-a—(0’—6)}. (37) 
a” — a—p;(b" —4) 
In these last four equations (a’,) (a’,) (0’,)(b”,) are the read- 
ings after being corrected, if necessary, for the heights of the 
meniscuses. These formule are sufficient for determining the re- 
lative diameters of the two branches of the siphon, and the mean 
temperature throughout the mercurial column. 
An example will serve to illustrate the process 
To test No. 366 Bunten’s mountain Sononiater: and to deduce 
the formula for the temperature of the mercurial column, I made 
the following observations, sf 
Upper redd- | Lower read- 
ing. | ing 
a sme od =365.04 A =1.73 | A =1.48 ¢ = 6.20 
Ob! 
per ton of up-|Heights of low-| Temperature 
r meniscuses.| er meniscnses. | of aoe 
~ 
4 =f! 
1 
2 
3 la” =394.64\b” =356.50| H” =1,80 | hk” =1.69 |e” =31.32 
4 fa a’ —389.60\b" =352.43) H”=1.77 | h’’=1.64 |” =21.40 
The second observation is any one of which the temperature 
-isdemanded. 'The remaining three were taken agreeably to the 
suggestions under (10.) And it is farther important in this case, 
that at least two of the upper readings should differ considerably 
from each other in value; which may be effected by observing 
at the base, and on the summit of a hill, or under different at- 
Mospheric pressures at the same place. In this example, how- 
ever, owing to the accidental loss of the barometer, the difference 
tween any two upper readings, is not so great as it ought to be. 
