[ 68 * ] 
Spirit ones juft mention^, which is the Liquor lofing 
of its Bulk by Evaporation $ and they congeal much 
fooncr than Water, and fo are ufclefs in meafuring 
any Degrees of Cold. 
The moft ufeful Inftruments, as they compre- 
hend the largeft Range, are the Mercurial Thermo- 
meters, which were brought into Ufe by that in- 
genious Artificer Fahrenheit , F. R. S. (See Rhih 
Tranf N°. 381.): But, to do Juftice to a moft wor- 
thy Member of the Royal Society , namely. Dr* 
Halley , he firft gave the Hint, and even propofed 
the making Thermometers of Quickfilver long be- 
fore Fahrenheit’s Time (See Rhil. Tranf, N°. 1 97. 
p. 652.). However, Fahrenheit deferves Thanks 
from the World for having brought thefe Inftru- 
ments into Ufe, becaufe they will meafure the 
greateft Degrees of Cold yet known 5 for no Cold 
hitherto obferved hath been able to freeze or render 
Mercury folid : And in meafuring Heat, they go far be 
yond boiling Water, even beyond the melting of Tin 
or Lead. Fahrenheit begins his Scale from o. the 
Point to which the Mercury hath been obferved to 
fall by the greateft Cold in Tfiand $ and com- 
putes, that the Mercury then * occupies 1 1 1 24, Parts. 
This is his Point of no Heat. Then reckoning up- 
wards from this, he finds that when the Mercury' 
is rarefied only 32 Parts or Degrees more, common 
Water juft begins to freeze: I11 a temperate Air it 
will rife to about 60. The moft fuitry Sunfhine. 
feldom raifes it to 90 ; the Heat of an animal Body 
to 96 5 the boiling of Alcohol to 174.,* the boiling 
of 
* See Boerh. Chem. Tom. I. p. 174. 
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