m order to afcerfain the height of Mountains* 561 
By former experiments I find the fpeciiic gravity of the quick- ^ 
filver of my barometers, compared with rain-water in 63 ° r 13.60610 1 
of heat, as, — — — — 
And 68 — 53°m5°, corre£l therefore for 15° of expanfion ofl Q1 g 
quickfilver, — — - — i 
Corre£t for 15° of expanfion of air, — — — • ° 3 r 
True fpecific gravity of quickfilver, with 53 0 of heat, 1 3*594 
Which multiplied by the ipecifie gravity of air, — x 83^ 
Feet* 
And laflly, A>th of an inch of quickfilver, when the barometer {lands at^ 
29.27 inches (viz, from 29.22 inches to 29.32 inches) with the tern- r 94.7 
perature 53°, is equal to a column of the atmofphere of, • — ■ J 
This quantity, according to my barometrical obfervations, is,. — » 93-83 
• -to Mr. de luc’s rules, — - — 91.66 
wjjfCJr 1 - s' . f ' ‘ • . 
We fee here then that the ftatical experiment agrees 
with the refult of my barometrical ones to within about 
11 inches in ioo feet, and I am not fure that it is not 
ffill capable of much farther precifion ; and though per- 
haps alone it might carry with it, to fome perfons, a lefs 
conclufive teftimony, who reluctantly reafon from the 
little to the great, yet, in conjunction with what has been 
before Ihewn, I think it has confiderable weight; and I 
am the lefs inclined to rejeCt fuch an indirect method of 
proof, as I have the great authorities of halley and 
newton on my fide'H. 
I have 
(z) “ Ce qu’il y a d ? effentlel a obferver ici, M fays Mr. de luc, “ et vrai- 
<c ment digne de remarque, c’eft que par la feule connoiffance des pefanteurs 
iC fpecifiques de Fair et du xnercure, halley eft parvenu a une regie ties 
Vol. LXVII. 4 D u approchante 
