200 APPENDIX TO MEMOIR OF PELTIER. 



For further details on this sulyect recourse may be had to the great treatise on 

 meteorology of Kaemtz, in 3 volumes, pp. 450, 500 ; the smaller treatise on 

 meteorology hy the same author, translated, with notes by Ch. Martins, p. 138 

 and seq.; the memoirs of Gasparin on the distribution of rains in Europe, 

 fBibUotltcque Universelle, i. 38, pp. 54 and 2G4;) a\\({ tXie Atlas Pln/siqite of 

 Berghaus, charts 10 and 12 of the meteorology, p. 19 and seq. of the test. 



The tables above given establish, therefore, the three facts in question : the 

 diminution of temperature, the diminution of the annual quantity of water, and 

 tlie diminution of the relative quantity of water falling in ^\•inter. What, now, 

 is the cause of these three phenomena ? what is the bond which connects them '? 

 It is this which we propose to explain while expressiug ourselves with all the 

 reserve which is proper on such a subject. 



The winds of the southwest bear from the Atlantic ocean a large quantity of 

 clouds and vapors ; these, nearly throughout Europe, are the winds pre-emi- 

 nently rainy. The clouds are formed of globules of transparent vapor and of 

 . globules of opaque vapor, both kept apart by the latent caloric and the elec- 

 tricity, which render them mutually repellant. If any cause abstracts from a 

 cloud the greater part of its electricity, one of the two forces which co-operated 

 to keep the globules separate is suppressed. The globules of transparent vapor 

 approach one another, are condensed, and transformed into opaque vapors ; the 

 globules of opaque vapor, for the same reason, pass into a liquid state, the dens- 

 ity of the cloud, its specific gravity, is augmented, the cloud sinks and falls on 

 the earth in the form of rain. On arriving at the surface the cloud disengages 

 the latent heat it possessed, and thus the soil, as well as the ambient air, is ren- 

 dered warm. 



The quantity' of rain which falls annualh' is naturally, all else being equal, 

 more abundant in western Europe than in the interior of that continent; the 

 forests, the mountains, especially' when wooded, radiate much electricity ; they 

 neutralize, therefore, the electricity of the clouds, and thus induce, in a nianner 

 more or less indirect, their precipitation. When this current froui the southwest 

 reaches German}' it is already deprived of a great part of its vajiors. AViien it 

 arrives in Hussia, there remains still less of them ; finally, in Siberia there is 

 scarcely any at all remaining. It thus appears that the quantity of water which 

 falls in a year must continue always diminishing as we penetrate into the interior 

 of the continent ; it is evident, consequently, that the quantity of latent heat 

 abandoned by the clouds must also progressively diminish, and that the tempera- 

 ture must undergo a corresponding abatement. These facts are more marked in 

 winter than at au}^ other season, because then the wind from the southwest brings 

 a less quantity of vapors, while these are less elevated and consequently termi- 

 nate at lower latitudes. Another cause, moreover, concurs in augmenting the 

 asperity of the cold in the interior of Russia : this is the intensity of the radia- 

 tion which takes place in consequence of the great serenity of a sky which is 

 obscured l»y neither cloud nor vajior. 



It results from what has Ik'cu just said, that a locality in Europe situated to 

 the east of a chain of mountains should always be colder, all else being equal, 

 than a locality situated to the west. The chain of mountains in efiect, by pre- 

 cipitating a great quantity of vajjors, must have abstracted a considerable por- 

 tion of the latent heat, which is hence naturally in deficiency on the other side ; 

 moreover, if these places are situated in a latitude somewhat high, where the 

 clquds are already very low, this effect will be still more decided. This in 

 reality is what occurs as respects Sweden and Norway in reference to the Scan- 

 dinavian Alps. We may cite as an eiiainple Drontheim in Norway, and Umeo 

 on the Gulf of Bothnia, in Sweden, (see TInstitut of 18th February, 1846, p. 61, 

 the communication of M. Martins.) These two cities are nearly in the same 

 latitude, and yet the mean temperature of Drontheim during winter is — 4°. 75, 

 while that of Umeo is — 10°. 2, a difterencc of 5°.45. 



