286 Professor AryJoun on the Theory 
placed, their bulbs being separated by about a quarter of an inch, and that of the in- 
strument occupying the higher position being invested with a tunic of muslin kept 
constantly moist with water. The blast was steadily maintained until the thermome- . 
ters ceased to rise, and the temperature of each was then accurately noted, the eye 
being assisted by a lens. Tables 1, 2, 3, and 4 exhibit the results of four distinct 
series of experiments thus conducted :— 
TABLE 1. TaBLe 2, 
February 8, 1835, 1] o'clock, a.m. February 9, 1835: 11 o'clock, a.m. 
Bi eels din | Bp t’ ob. | t” cale. Diff. t wv d P t’ ob. | t” cale. | Diff. 
1 | 49.6 | 44.7} 4.9] 29.6 | 40 | 39.02 | —.98 | 1 | 47.2] 42.5| 4.7] 30.02] 38 | 36.58 | —1.42) 
2 | 88.5 | 62 | 26.5] 29.6 | 40 |*39.18 | —.82 ] 2 | 76 57.5 | 18.5 | 30.02} 38 | 40.44 | +2.44) 
3 | 80.5 | 59 21.5] 29.6 | 40 | 39.27 | —.73 
Taste 3. ¢ TABLE 4. 
March 4, 1835: 11 o’clock, a.m. March 25, 1835: 11 o’clock, a.m. 
t tv d P t’ ob. | ¢” cale. Diff. t t d Pp t’ ob. | t' cale.| Diff. 
48.3 | 43 5.3 | 29.76 | 37.5 | 36.41 | —1.09] 1 | 51.3] 45.5] 5.8] 30.7 | 38.5-\ 38.61] +.11 | 
96 64 | 32 29.76 | 37.5 | 36.37 | —1.13 2 82 59 23 30.7 | 38.5 | 36.7 | —1.8 | 
91 | 62.5| 28.5 | 29.76 | 37.5 | 37.66 | + .16 
75 |56 |18 | 29.76 | 37.5 | 38.26 | + .76 
The results exhibited in the preceding tables will, I believe, be considered by many 
as going far towards establishing the accuracy of my theoretical views. Although the 
depressions vary from 4°.7 to 28°.5, the differences between the observed dew-points and 
Rone 
those deduced from the formula, are certainly not greater than what may fairly be 
ascribed to unavoidable inaccuracy of observation. But for the purpose of putting 
this matter in a still clearer point of view, I have calculated a number of values of m, 
the constant of our formula, from the preceding observations. This was easily done ; 
for as all the observations in the same table refer to air in the same Beer a state, 
each series should give. the same dew-point, and the pan i f'-md x = must 
have in reference to them a constant value. f’ —md xz = o for one must therefore be 
qeval to F’ —mDxk for any other—an equation hea which we deduce m= 
D = nies The si icaiita of this method gives us the following values of m :— 
TABLE I. TABLE 2. 
(land 2) (J and 3) (2and 3) (1 and 2) 
m = ,01155 ak -01185 mae -01075 m = .01489 
TABLE 3. 
(land 2) (land3) (land 4) (2 and 3) (2and4) (Sand 4) 
m= O1879, om O88 7%...» GOL809s...., 00825), ... .00976 ..., .01045 
TaBLe 4. 
(1 and 2) 
m = .00967 
