of Snow around Plants. 248 



vations which are more or less hollow superiorly, and more or 

 less deep. This effect, in favourable circumstances, is very 

 conspicuous. Among other instances, M. Fusinieri cites the 

 winter of the year 1830, in which the ground in Lombardy was 

 entirely bare around trees and shrubs, whilst the snow re- 

 mained two and a half feet thick in the middle of the fields. 



Nothing is easier than to prove that the cause which pro- 

 duces this speedy solution is not a heat which is peculiar to the 

 plants in their living state, for precisely the same phenomena 

 are observed around poles and stakes which are fixed in the soiL 



Snow is also melted by the action of branches and twigs 

 which are situated above it. In fact, all the soil which is im- 

 mediately beneath trees and bushes, as well as a limited space 

 around them, is cleared before any other part of the surface of 

 the ground. 



To demonstrate that this effect is owing to the calorific ac- 

 tion of the branches, and not to the smaller quantity of snow 

 which lies there, you may suspend dry branches or those which 

 have been lately cut, at a certain height above the surface, in 

 the midst of a plain which is covered with snow, and you will 

 find, in these circumstances, in which the snow is to a certainty 

 of equal thickness, that precisely the same phenomena occur ; 

 that is to say, that beneath these bodies there is speedily formed, 

 at the surface of the snow, hollows, which gradually extend in 

 breadth and in depth, and which would penetrate to the soil, 

 if the experiment were sufficiently prolonged. 



Other circumstances being equal, the action of plants is 

 greater in proportion as the twigs and branches are more nu- 

 merous and slender. It commences at noon, and then progres- 

 sively extends, to the west, to the east, and finally reaches to 

 the lateral portions of the snow which are situated to the north 

 of the tree. Hence it may be deduced, that the principal cause 

 of the phenomenon arises from the solar heat which is directly 

 communicated to the trunks and branches of trees, and thence 

 radiated upon the surrounding snow. 



And now the great objection of M. Fusinieri occurs. How 

 is it possible, says he, that a body heated by the influence of 

 radiated caloric can produce a greater effect than the direct 

 rays themselves ? the heat emitted by the plants must be much 



