C 168 ] 
divided with the interval between freezing and 
boiling water = 200, and the freezing point be 
marked — 9, and the boiling point -f- 19 r, and the 
heights of this thermometer, at the two Nations, 
be called G and I, we fhall have — — - - + 1 
449 2X500 
= For F — 40 — F — 32 — 8, is the height 
of Fahrenheit’s thermometer, reckoned from 8 de- 
grees above freezing, and 449 : 500 ;; 180 : 200 ;; 
P* , 0 g 
8 : 9, and the fraction hi — if both the nu- 
449 
merator and denominator be increafed in the ratio 
of 449 to 500, will become — f - TT x 
_ F- 32 |9|-, _ n + l _G + I becaufe G+J 
500 2X5OO IOOO 2 
JF — 22 X Therefore, if the thermometer 
of the barometer has the freezing pointmarked o, 
and the point of boiling water 81,4, and the dif- 
ference of its height, at the two (lations, be called 
d\ and the thermometer for meafuring the tem- 
perature of the air, be divided with the interval 
of 200 between the freezing point and that of 
boiling water, and the firft be marked — 9, and 
the latter -f- 19 1, and the degrees, fhewn by this, 
at the two ilations, be called G and I ; the formula, 
that will give the height of the upper ftation 
above the lower one, in Englifh fathoms, will 
be log. B — log. b d x 1 > which 
confequently multiplied by 6, will give the height 
in Englifh feet. It is to be obferved, as before, 
that — d or -4- d is to be ufed, according as the 
thermometer, attached to the barometer, is higheft 
7 at 
