- 3 8 , x 
JH. Alexander on the Tension of Vapor of Water. 319 
uch accuracy as the nature of the research admitted, it follows 
that, in spite of all the extraordinary tact and skill of the obser- 
ver, there is yet primd facie evidence against the absolute accu- 
racy of the results. It is to be remarked upon the column of 
temperatures, both here and hereafter, that the remote decimals 
renheit, and are preserved because they added to the accuracy, 
while they did not increase the labor of the clei Never- 
theless, phe thermometer of Mr. Regnault could be rea d diregily 
to the 5, of a degree Centigrade, corresponding very nearly to z 
of a degree Fahrenheit ; and by estimation, to the: next decimal 
place. | 
The temperatures of this table under 32°F, are lowe 
pressures have ever been observed at before, and 1 rest upon single 
observations. They do not admit, therefore, of a comparison oth- 
as b l i y numerous, and allow of being com- 
pared among themselves. Of the forty-seven observations, whose 
arithmetical mean pressure is given in the table, the diene 
"maximum was se: peek corresponding to a temp. by formula of 30°-72 Fahr. 
and minimum 29 -77 Fahr. 
and the difference 0 -00768 responding diff, of temp. 0-95 
J 
This difference shews a mean error in temperature, unaccount 
for, of 0°-425 Fahr. ; and a limiting error in pressure rather m 
than half the difference between the formula and the mean of all 
the observations. 
In the various series of Mr. Regnault, the temperature is given 
sometimes by one thermometer only, and sometimes by two, and 
we four. Of these latter classes, I have taken out of each se- 
the observation where the difference of reading of the seve~ 
| the rmometers is the greatest, to serve for another comparison, 
as follows: 
re 
% 3 THERMOMETER. | 
4 Series.” Maximum. Minim Differences. | 
rT 2 A “33°61 Cent.| 330-49 Gakiigr: 0-12 Cent. | 
ied 42 -63 42 -56 0: pes 
N. 43-64 | 42 -84 0 -81 
‘ 0.) |47-84° | 47-14 * lo -70 li " 
P. 47 -87 0 -87 
2 91 +25 91 -06 0: Pi ee 
7. 122 -72 122 -50 0: ee 
8.10 “72 110 -64 ae ene 
or. 137 -75 137 -52 0: er 
“ on ae | 
“ Mean temperat. 7521 ‘154 Cent. ; ; mean difference 0°- 366; : Fe sponding 
Re tern Yin a 
