Central Part of British North America. 219 
1857-8, Fort Carlton. 
Mean Temp. Mean at Mean at 
Month. of Air. ' Two Feet. | Three Feet. 
November, . A : 17°3 35'8 366 
December, . : ; 8:9 30°4 32°8 
January, : : : 0°0 23°4 29°3 
February,* . : : 74 18°3 24°3 
March, . : ‘ ° 263 24°6 25'°3 
April, . : : 35°8 30°3 30°2 
May, . : : ° 45°0 33°8 31°6 
June,t . 5 : F 549 38°6 30'8 
1858-9, Fort Edmonton. 
November,} . : 26°45 35°7 f 
December, . ; : 76 23°4 s 
January, : : ; 9°55 20'8 a 
February, . i 1:25 17°6 2 
March, . : F ; 23°0 25:2 a 
DE : : ; 311 30°3 es 
May,§ . : : ; 47°9 32°k 
(The thermometers were sunk in brass tubes attached to a 
light wooden rod, and had the bulbs protected with flannel, to 
preserve them from the influence of the atmosphere while they 
were removed for examination.) 
At Fort Carlton observations were also made by M. Bour- 
geau almost daily, in order to determine the temperature 
within the trunks of large trees. For this purpose ther- 
-mometers were placed obliquely into the heart of a Populus 
balsamifera two feet in diameter, and of an Abies alba of 
the same size. ‘These observations only served to show that, 
as might be expected, the temperature of the trees accords 
much more closely with the mean temperature of the atmo- 
sphere than does that of the soil, even at the depth of only 
two feet; and further, that there is no marked difference at 
very low temperatures between the resisting power of ever- 
green and deciduous trees. The means of these observations 
were as follows :||— 
* First seventeen days only. t First eight days only. 
t From 9th to 30th, § First eight days only. 
|| Some of these observations have been printed in the Proceedings of the 
Linnean Society, 1859, 
