158 Miscellaneous. 



On the Heating of the Soil of high Mountains, and its Influence 

 upon the Limit of eternal Snow and Alpine Vegetation. By Ch. 

 Martius. 



Theory indicates, and experience proves, that the atmosphere ab- 

 sorbs a notable proportion of the heat transmitted by the sun to the 

 earth. M. Pouillet estimates this quantity at '4 of the total heat 

 transmitted by the sun to the earth at any given moment. As the 

 calorific ray which falls upon an elevated summit traverses a less 

 considerable thickness of the atmosphere than that which arrives at 

 the level of the sea, it ought to heat the summit of the mountain 

 more than that which penetrates as far as the plain ; but the rarefied 

 air surrounding the summit does not become so much heated as that 

 of the plain : hence it should follow that the soil at the surface and 

 for about a foot deep, upon a high mountain, should become more 

 heated than the air, while the contrary would take place in plains 

 little elevated above the sea. Now this is fully confirmed by expe- 

 rience, as I show in this notice, through observations made in August 

 1842 on the Faulhorn by MM. Bravais and Peltier, and in Sept. 1844 

 by M. Bravais and myself, compared with corresponding ones made 

 at Brussels by M. Quetelet, and with those made in Spitzbergen 

 in 1839 by the Meteorological commission attached to the expedition 

 of • La Recherche.' 



This relatively considerable heating of the surface of the soil exerts 

 a powerful influence upon the physical geography of the high Alps : 

 it is this which moves upward the line of eternal snow, the melting 

 of which is principally due to the heat of the subjacent ground. All 

 travellers who have ascended these elevated regions know that in the 

 Alps the snows melt underneath in consequence of the heat of the 

 soil. Often, when the foot is placed on the edge of a snow-field, 

 the weight of the body breaks a superficial crust which does not rest 

 on the soil. Sometimes we perceive with astonishment underneath 

 these icy vaults Soldanellas in flower (Soldanella alpina, L., and 

 &. Cludii, Thorn.), with tufts of the leaves of the Dandelion. It is 

 likewise the melting of the snow in contact with the soil which causes 

 the sliding of the snow-fields which form the spring avalanches of 

 turfy declivities. Finally, it is this heating which explains the variety 

 of species of plants, and the number of individuals which cover the 

 soil at the very limit of the eternal snows : thus, upon the terminal 

 cone of the Faulhorn, the height of which is about 250 feet, the 

 superficies about 1 1 acres, and the altitude nearly 9000 feet, I have 

 gathered 131 species of Flowering plants. On the Grands-Mulets 

 (needles of laminated protogene rising in the midst of the glaciers 

 of Mont Blanc, at 10,000 feet above the sea), I have noted nineteen 

 Phanerogamia, — viz. Draba vladinensis, Wulff., Cardamine bellidi- 

 folia, L., Silene acaulis, L., Potentilla frigida, Vill., Phyteuma 

 hernisphcericum, L., Erigeron uniflorum, L., Pyrethrum alpinum, 

 Willd., Saxifraga bryoides, L., S. groenlandica, Lap., <S. muscoides, 

 Auct., Androsace helvetica, Gaud., Avena pubescens, DC, Gentiana 

 verna, L., Luzida spicata, DC, Festuca Halleri, Vill., Poa laxa, 



