and the Distribution qf Meat over the Globe, 29 
over the globe, as deducible from the thermometrical variations 
of the air, we are far from considering these laws as the only 
ones necessary to resolve all the problems of climate. Most of 
the phenomena of nature present two distinct parts, one which 
may be subjected to exact calculation, and another which can- 
not be reached but through the medium of induction and ana- 
lOO^V. 
O*; 
Having considered the division of heat between winter and 
summer on the same isothermal line, we shall now point out the 
numerical ratios between the mean temperature of spring and 
winter, and between that of the whole year and the warmest 
month. From the parallel of Rome to that of Stockholm, and 
consequently between the isothermal lines of 60°.8 and 41°, 
the difference of the months of April and May is everywhere 
10°.8 or 12°.6, and all the successive months are those which 
present the most rapid increase of temperature. But, as ii> 
northern countries, in Sweden, for example, the month of 
April is only 37°.4, the 10°.8 or 12°.6 which the month of 
May adds necessarily produces there a much greater ef- 
fect on the developement of vegetation than in the south of Eu- 
rope, where the mean temperature of April is from 53°.6 to 
55°. 4. It is from an analogous cause, that in passing from the 
shade to the sun, either in our climates in winter, or between 
the tropics on the back of the Cordilleras, we are more affected 
by the difference of temperature than in summer and in the 
plains, though in both cases the thermometrical difference is the 
same, for example from 5°. 4 to 7°.2. Near the polar circle, the 
increase of the vernal heat is not only more sensible, but it ex- 
tends equally to the month of June. At Drontheim, the tem- 
peratures of April and May, like those of May and J une, differ 
not 10°.8 or 12°.6, but 14°.4 or 16°.2. 
In distinguishing upon the same isothermal line the places 
which approach its concave or convex summits, in the same sys- 
* In calculating for Europe, from 46° to 48° of Lat. for ten years the mean 
temperatures of every ten days, we find, that the decades which succeed one another, 
differ near the summits of the annual curve only 1°.44, while the differences rise 
in autmnn from 3°.6 to 5°. 4, and in spring fi'om 5°.4 to 7 °, 2 . — H. 
