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ing ice, in hundredths of a degree of M. de luc’s 
fcale; and a the conftant number 10387 W. 
It is proper in this place to inform the reader, 
that M. de luc, by logarithms, always means 
the tabular or Briggian logarithms, and confiders 
the y figures given by the tables, befides the in- 
dex, as integral figures; that is, he confiders the 
eighth figure of the logarithm as Handing in the 
place of units. Throughout this paper, I have 
conformed myfelf to this manner of conceiving the 
tabular logarithms, that, upon the fame fubjedl, we 
may fpeak the fame language. But it is more 
ufual, with mathematicians, and, in general, it is 
more convenient, to confider all the figures, after the 
index, as decimals. Thus the number, which M. 
de luc exprefies by log. y, would, in the 
common mathematical flile, be ? -- * log. y; or, 
99x5° lo s- y- 
It is but feldom that the barometer in this coun- 
try ftands fo low as 27 French inches. 30 inches 
Englifh are little more than its mean height upon the 
(by Ibid. §. 961. and 1*43. note a. It may feem doubtful 
whether there is not a (mail error in the conftant number 10387;- 
The experiments for afcertaining the variation of the boiling 
point were made with a thermometer, of a peculiar fcale;. and 
the formula deduced from them was this, |4^o<5crc> log. y — 5015 
= the height of the thermometer, plunged in boiling water, 
above melting ice, in parts of that peculiar fcale. Recherch. 
fur les Modificat. de FAtmofphere, §. 960. Now a degree of 
this fcale was afterwards found to be to a degree of M. de luc’s 
common fcale as 80 to 3869!. And this proportion be- 
tween the degrees of the two fcales, gives 10368,9 or 10369; 
very nearly, inftead of 10387, for the value of the conftant 
number a, in the formula for hundredths of a degree of the 
common fcale. 
plane 
