in order to af certain the height of Mountains, 579 
the height of the uppermoft barometer reduced to the 
fame heat as the lowermoft: and in table II. oppofite to 
25.200 inches and 29.400 inches, 1 find refpeCtively 
6225.0 and 2208.2; their difference 4016.8 is the ap- 
proximate height in feet. The degrees on the ther- 
mometer in the open air, 39°^ and 45 0 being then added 
together, and afterwards divided by 2, give for the mean 
temperature of thefe obfervations 42°^, or n° above 
the ftandard temperature, 3 1°| : and laftly, the correction 
for 1 1°, in table IV. on 4000 feet I find = 106.9, and 
on 16 feet = 0.5; that is, 107.4 f' eet e( l ua ^ ^ ie whole 
correction, which added to 4016.8 gives 41 24.2 feet for 
the correCt height of the mountain. 
EXAMPLE 11. 
Suppofe the height of the barometer at the top of a 
rock had been obferved at 24.178, the attached ther- 
mometer at 57 0 . 2, the air-thermometer at 56°; the ba- 
rometer below at 28.1318 inches, the attached thermo- 
meter 6i°.8, the detached one 63°. 9 ; what is the height 
of the rock? 
4 F 2 
Obfer- 
