[ 226 ] 
fame, as © expreffes in parts of the other; and, 
therefore, putting p, and -jp, for the values of the 
hundredth part of a degree, of the fcales of M. de luc 
and bird refpedively, the fradions -j-, — are always 
equal, and T, 0, are in the conffant proportion of 
the invariable numbers L, B : confequently, when the 
proportion of T and 0 is determined for any par- 
ticular value of 2:, it is found generally for all. 
Therefore, as was affirmed, 
T:0 = 809 : 1 800. 
And T ra © = voVo G ver V nearl y ^ i° all values of z a 
and fubffituting this value, for T, in the equation ex- 
hibiting the relation between % and T, we {hall 
have, for the relation between z and 0, 
99 
20000000 
99 
log. 3—41,7155 = 
8 99 
2000X100 
© 
0 . 
Or, — — 0-3 — log. % — 92,804 = ——the height 
of the thermometer in boiling water, above melting 
ice, in degrees of bird’s Fahrenheit, when the 
height of the barometer, in ioths of an Englifh 
inch, is z. And thus M. de luc’s formula , for 
the variation of the boiling point, is adapted to 
Englifh inffruments, and reduced to Englifh mea- 
sures of length. 
{c) Tt might be fufficiently accurate for mofi purpofes,to fubfti- 
tute -is © ( — -ttb ®) for A°c?o ®. The error of this fubditu- 
tion would be about ; and confequently would amount to 
about % of i° of bird’s Fahrenheit, when z is 300. But the 
error in the fubftitution I have ufed is much lefs, not amounting 
to -gTst nj ©, which makes lefs than A of a degree of bird’s fcale, 
in. the fameeafe. 
For 
