[ 2 9 l ] 
EXAMPLE II. 
March 26 
28 
h 
20 
21 
B r . ob- 
T r . 
T*. 
K r . reduced 
ferved. 
in. 
out. 
to common 
- 
— 
— 
temperature 
3°>°7 
J8 
59 
30,058 
3°, 21 
54] 
5° 
3 °, * 5 * * * * * * * * * * * * * * * 21 
Dcnfities, by 
5. prob. 4. 
1 379 6 ,6 
14138,2 
Hence /> = 10. * = 19. ^=449. $r + j = 468- s — p — 9. f = 52. 
5 P 
0=0.0106238. 4=0.0084332. D — ^=0.0021906=21,906 
fathom. Therefore, Aj 3 1=1164,42 fathom—1,32 
miles ; and at a height infenhbly greater, the prefliire 
was the fame in both conditions. 
In this manner may the heights be determined, 
in which either the denfity or preffure of the air, in 
a given temperature, is the fame as in any greater or 
lower temperature; provided the proportion be 
known between the denfities, in the different tem- 
peratures, at the level of the fea, or at a given 
elevation above it ; otherwife both the problems are 
indeterminate. And I know no method of afeer- 
taining this proportion, but by a&ual obfervation of 
the barometer. The change of temperature deter- 
mines the proportion in which the fubtangent of the 
atmofpherical logiftic is changed ; but in whatever 
proportion the fubtangent of a logiftic is changed, 
the ordinate, at a given point of the afymptote, may 
be of any imaginable length, or may bear any ima- 
ginable proportion to the fubtangent. There is no 
given geometrical relation, in the nature of the 
curve, between the length of the one and the other ; 
and experiment hath not yet brought to light any 
phyjical relation in the particular cale in queftion. 
Diligent obfervation of the barometer and ther- 
P p 2 mometer 
