DISTRIBUTION OF TEMPERATURE ON THE EARTH. 24] 
of which 23 are in North America, and 9 on the western coasts 
of Europe. The second system comprehends 25 stations, from 
the southern declivity of the Alps, to Helsingfors in Finland; 
the means for each system for the same epochs are first given, 
and then the simultaneous deviations from those normal tempe- 
ratures*, 
Professor Dove remarks that the inspection of the tables gives 
a clearer view of the distribution of temperature than any verbal 
description can do, as in the vertical columns the eye traces in 
one direction the succession of the phznomena, and in the ho- 
rizontal ones their simultaneous existence. The following prin- 
cipal results, however, may be mentioned :— 
In considering the results of the five-day means, we observe 
that the deviations with negative signs make their appearance 
in two different manners; either they extend over the whole 
ground of observation, and their relative maximum is found in 
the northern stations, more particularly at St. Petersburg; or 
they are distributed over the middle and southern stations, in 
which case the maximum is at St. Gothard, while at Peters- 
burg we find large positive deviations. The diminution of tem- 
perature of the first kind appears to be generally more lasting 
than that of the second, and it is frequently very evident that 
the absolute extreme appears first in the northern regions. 
During the continuance of such low temperatures, the deviations 
on the St. Gothard do not appear to be very large, but even 
smaller than on the plains. There are therefore two kinds of 
diminution of temperature,—one of very extensive action, which 
seems to have its source in high latitudes, and one more local in 
its effects, which comes down from the mountains. The fact of 
the cold of the first kind being more intense on the plains than 
on the mountains, proves that the cooling polar current is prin- 
cipally in the lower regions of the atmosphere, while the warm 
equatorial current flows over it in an opposite direction. The 
abnormal effect of the mountain cold appears from the tables to 
* The extent of the tables in question precludes the possibility of their re- 
petition in these Memoirs : the reader who desires to study them adequately 
and fully, is referred to the original work. It is hoped that the present abstract 
contains all that is essential towards enabling the English reader to derive the 
full benefit from the inspection of the valuable numerical data and results, which 
form by far the larger portion of the work, besides placing before him the prin- 
cipal inferences which are drawn in the text. 
