126 Professor Adams on the Theory of the Thermometer. 
and diminished by condensation, and if this is the case, the 
additions of equal quantities of heat will give smaller incre- 
ments of temperature at high than at low degrees, which 
must to a certain extent render the thermometer inaccurate 
in higher degrees, though probably only to a very small 
extent, of little importance as to all practical purposes; and 
this cause of inaccuracy appears to be counteracted by 
another, that fluids seem to be more expansible by heat in 
proportion as their temperature is higher.*” “ 
~ Many other similar quotations might be made from the 
most distinguished late writers, were it deemed necessary. 
It is not my design to examine separately those which have 
been produced. The wide discordance of the results must 
be seen upon the slightest inspection. It is also sufficient- 
ly apparent, that there has been much loose experimenting, 
hasty generalization, and erroneous reasoning, as well as a 
great departure from the cautious spirit of the Baconian 
philosophy on this subject. ‘ Aliquando dormitat bonus 
Homerus.”’ If the thermometer is to be graduated ac- 
cording to any of the preceding conclusions. whose results 
shallbe preferred? But it is believed, it. will appear from 
the following remarks upon the preceding quotations, that 
the construction of the thermometer has no connection with 
hypothetical considerations, but that it is founded. upon 
facts unquestionable in their nature, and ascertained without 
difficulty. u ! oy aoned) ail 
_ First, then; the thermometer viewed as the measurer of 
temperature, is, like other standards of measurement, an in- 
strument of a conventional nature; its construction always 
has been, and must be founded upon facts, and must in no 
degree be connected with hypothetical considerations. A 
different number of facts have, it is true, since the invention 
of the thermometer, at different periods, been used in its 
construction; but still they were always facts and not hy- 
potheses. By temperature here is meant, the energy, in- 
tensity or degree of action of the unknown cause, caloric; 
and by differences of temperature, different degrees of en- 
ergy in the action of this cause. The thermometer in its 
indications, gives merely differences of temperature. 
* Elements, p. 51. 
