327 
wo uld make, — to ‘this pressure, a temperature of 
= 589°. ‘92 F. or 293°°3 Cent.; differing from the other within the 
© eorreetion between a mercu aria. al and an air-thermometer. 
; “Tt is at the other extremity, where we still have opportunity of 
| ‘s ix. ec to experiment, that the difference between the two for- 
mule be 
: mes more marked; and where that of Mr. Biot, 
a neither i in its terms nor its Poperesstt, can be considered applica- 
“ble. This may be seen as under: 
peratures, S z & = | 
Precsifec in inches of 
2 “Mercury. Observed by Ramu 7 3 i ais 
_0in-024 — 23°-83 iS es. : —22°-46 
7 2033 = 20°: - : -17°: —19 -52 
ae About the same time with Mr. Biot, other formule claiming 
(like that of Mr. Roche) a foundation on abstract theoretical prin- 
ciples, were proposed by Mr. Russell ; who has also applied their 
somewhat extensive, logarithmic apparatus to the calculation of a 
table of»pressures for each degree from 32° to 250° Fahr., and 
then for intervals of one or more atmospheres up to fifty. “This” 
does not properly come into this discussion ; because the author 
has found it necessary to employ different terms above and below — 
the point of boiling water, and in point of fact to have two for- 
mul ; an inconvenience, the same in kind, though not in degree, _ EB 4 
with what the object of the very research is to avoid. DNomgiag eee 
they both deviate in their respective directions from the eurve — 
given by observation; the pressures calculated by them, are, at 
the two extremities, very much above any experimental ones. 
Not to trouble ourselves with the part of the scale below the 
boiling temperature, where the errors are not of so much practi- 
eal importance, I give a few instances in the higher degrees, con- 
trasted with the results of the French Academy. me 
es Te ratures, (Fahrenheit.) 
ein Atmospheres ~ French vette | _ Russell’s Table. Differences. 
, 1 age DPD. ha 212° =< 
wi 5 307°:5* 306 -8 0°-7 
- s & 10. 358 -9 355 -6 3°3 
se 20- SAS 410 8 5 
il rr ab 457 -2 444 6 12 6 
50 510 -6 491 -4 19 -2 
‘WT ho feel of Mr, _Regnault, to whose experimental research- 
es such resort has been hadyare in one respect in the sam cate- 
gory as those of Mr. Russell: they are three, one adapt e 
ge 7 
* Mr. Russell in his ‘comparison, = well as the Franklin Inst in theirs, giv 
Bek pies at 308°-8 ;’ an error which has arisen fro m hastily re 
Centigrade temp. of 153° ‘08, as if it were 1 50. ; oa oe 
