Vegetable Productions of the Hudson‘s Bay Countries, Sll 
The isotJiaral line, or line 'of equal summer-heats, which in this 
instance is + 67.8®, on the contrary, when carried across the 
Atlantic, diverges to the southward nearly three degrees of lati- 
tude, passing to the southward of London, Brussels, and Paris, 
which lie in the isothermal band of from 50® to 52®. In more 
interior continental situations, however, the isothseral line again 
curves to the north, passing to the north of Warsaw in 
Lat. 52.25°, on the isothermal line of +19®, and to the south 
of Moscow in Lat. 55.75®, and on the isothermal line of +40» 
In the interior of Siberia, the severity of the winter being great, 
it is more than probable that an entirely similar climate may be 
found. Humboldt, in one of his tables, has assigned the mean 
summer-heat of Cumberland House to Central Russia, in Lat. 
58® 30', and Long. 36° 20' E., and to Canada, in Lat. 
Long. 71® W., on the isothermal line of 41. The low summer- 
heat here assigned to Long. 71®, in Canada, may be ascribed 
to its much more maritime climate, when compared to the inte- 
rior situation of Cumberland House. The differences of these 
climates may be rendered more manifest by the following tabu- 
lar view. 
Table VII. 
Difference of Summer and Winter on the Isothermal Line of 
+ 32®. 
Situation, 
Winter. 
Summer. 
Difference 
’ Cisatlantic Region, Long. 1° W. and 17° E. 
-{-14.0° Pah. 
-1-53.6° 
39.6° 
Transatlantic Region, Long. 58° W. — 72° W. 
-1- 1.4 — 
-1-55.4 
54.0 
Cumberland House {Continental) 102^ W. 
— 4.9 — 
-f67.8 
72.4 
The effects of the Cumberland House climate, which may be 
considered as a perfect specimen of the interior continental cli^ 
mate,, seems to be, as Baron Humboldt has somewhere remarked,, 
that, after a long and severe winter, there is generated a great 
degree of irritability, both in animals and vegetables, which 
renders them more susceptible of the succeeding summer-heats. 
It may be, that it is this excess, as it were, of irritability, that 
renders the puncture of the mosquito so much more distressing 
at Hudson’s Bay than in any other part of the world, and not 
the more poisonous nature of the insect itself. 
