128 — on the ee of the Thermometer. 
measure furnished by nature, sae upon the ¢5 445555 part 
of the length of the meridian, as thew standard, and this, by 
the name of metre, forms the basis of their regular and beau- 
tiful metrical system. The dollar, containing 371.26 grains 
of pure silver, and 44.75 grains of copper, is agreed upon in 
the United States, as the standard to which all other coins, 
as well as all monies of account, are to be referred The 
general agreement to consider these as standards of measure 
of their own kind, is what constitutes mem such standards. 
The case is the same with the thermometer. Until the 
late attempts to introduce hypothetical Se aothow into 
its construction, the dilatation of mercury was univers 
agreed upon as the standard for measuring the different de- 
grees of energy of caloric, i. e. as the standard for measur- 
ing temperature. The whole dilatation between the deter- 
minate points, is divided into a convenient number of equal 
parts; (50, 100 and 180 are the principal numbers which 
have been used,) and the scale which results from this 
graduation is conventionally used to measure all tempera- 
tures between its extreme points. It is with as much rea- 
son, that the thermometrie scale is equally divided into 180, 
or any other number of equal parts, as that the yard is divi- 
ded into 3, 36, &c, equal ae: Even if the hypothesis were, 
beyond question, true, that caloric is a material substance, 
and that the introduction of oe parts of agiven quantity of 
itinto the mercury of the thermometer should expand it 
from 32° to 122°, while nine parts should be sufficient to 
expand it from 122° to 212°; still the circumstance ought 
not to affect the graduation; because the thermometer is 
designed to measure the energy of the action of caloric, and 
not the quantity of it introduced or disengaged. It is one 
thing to measure the quantity of caloric received into @ 
dy, or removed from it, and another to measure the iv- 
tensity of j i action. These by no means necessarily cor- 
respond with each other. 
