in order to afcertain the height of Mountains. 575 
by heat, expreffed in thoufandth parts of an Englifh 
inch; which added to the coldeft barometer, or fubtradted 
from the hotteft, will give the height of the two barome- 
ters, fuch as would have obtained had both inftruments 
been expofed to the fame temperature. 
Precept the 2d, With thefe corrected heights of the ba- 
rometers enter table II. and takeout refpedtively the num- 
bers correfponding to the neareft tenth of an inch ; and if 
the barometers, corrected as in the firll: precept, are found 
to Hand at an even tenth, without any further fradtion, the 
difference of thefe two tabular numbers (found by fub- 
tradting the lefs from the greater) will give the approxi- 
mate height in Englifh feet. But if, as will commonly 
happen, the corredt height of the barometers fhould not 
be at an even tenth, write out the difference for one. 
entire tenth, found in the column adjoining, intitled 
Differences’, and with this number enter table III. of pro- 
portional parts in the firft vertical column to the left- 
hand, or in the j ith column, and with the next decimal 
following the tenths of an inch in the height of the. 
barometer ( viz. the hundredths) enter the horizontal 
line at the top, the point of meeting will give a certain 
number of feet, which write down by itfelf; do the fame 
by the next decimal figure in the height of the barome- 
ter ( viz. the thoufandths of an inch) with this difference, 
(hiking 
