CHEMICAL AND PHYSICAL NOTES. 163 
TaBLE XXI., Giving REsvuLTs oF OBSERVATIONS OF THE TEMPERATURE OF THE AIR 
AND ITs VarraTions at Sr. Morirz. 
Number of intervals in Mas mugs rise 
. ¥ hich th t or fa 
vamwor | Vis | tereat] whlenatg remaster 7 oat | outta 7 
Date, 1894. Sbace vation: temper- | observa- of 
ature. tions. __ | intervals. 
Rise. | Fall. Ledeen Rise. | Fall. 
fey m” °° °o 
25 Feb. .| 6.24 a.m.| —8:0 60 32 22 13 67 0°51 | 0°50 
to 
T8245 -—5:'0 
26, +«.| 11.10 ,, +8°25 20 32 33 61 126 | 0°13 | 0°50 
to 
1.19 p.m.) +3°5 
27, ~.| 6.55am.) +1°75 20 80 43 45 168 | 0°37 | 0°47 
to 
8.40 ,, +5°35 
28 Ci, 7.0 =~, —6:48 20 103 37 45 185 | 0°25 | 0°20 
to 
8.2 , | —1:0 
1 March| 6°30 ,, — 4°25 15 93 68 80 241 0°25 | 0°20 
to 
7.30 4, —2:1 
2 3 6.38 ,, —6°23 13 158 118 181 407 | 0°23 | 0°18 
to 
86 ,, —2°03 
Boy 6.30 ,, —6°55 20 120 89 17 285 | 0°28 | 0°20 
to 
86 —1°68 
ments in calm air outside and in still air in a room, we find that for 
this thermometer to rise or fall 0°°5 C. in twenty seconds the tem- 
perature of the air around it must be from 2°°25 C. to 4°°65 C. hotter 
or colder than the thermometer. Taking even the lowest of these 
values, we see how great the possible error is in measuring the 
actual temperature of the air at any moment with a thermometer, 
and the error is the greater the more sluggish the instrument is. In 
Table XXII. the detailed observations are given for a few minutes 
on the 2th of February, when the temperature was changing very 
rapidly. In the third and fourth columns the rise or fall of the 
observed temperature is given. In the fifth and sixth columns the 
corresponding differences between the temperature of the air and 
that of the thermometer which would cause the observed rate of 
change of temperature are given; with these and the observed 
temperatures we obtain the amended temperatures of the seventh 
column. Although it was snowing on the 26th, the air was per- 
fectly still, and the rate of cooling corresponding to the ‘term’ 
M 2 
