STATEMENT BY M. MARCHAND. 249 



measures they did, as means of diminishing, at least provisionally, 

 the danger. The torrents in the Alps which have given occasion for 

 the study of these phenomena owe their origin to the melting of snow 

 on higher lying mountains in summer, and to orages, or tremendous 

 storms of rain, which fall in spring. These torrents occasioned by the 

 latter are generally the most destructive. 



" M. L. Marchand, Garde General des Forets, says on this 

 subject, — " When the torrential rains of tha Alps are made a subject 

 of study it is soon seen that they are all of them occasioned by a 

 particular wind called the foehn. These winds are generally violent, 

 and present almost always the chiiracter of orages, or storms of rain ; 

 it follows that great quantities of rain are poured down upon the soil ; 

 and to this may be attributed disasters sometimes coming upon spots 

 which seemed to be placed in the best possible situation and circum- 

 stauces to bear the most persistent rains. 



" The fcehn is a wind which blows from the south, often with 

 extraordinary force ; it is peculiar to the Alps, and is felt throughout 

 their whole extent. Having climbed over Italy, where it is no other 

 than the sirocco, the following are its chief characteristics : — It comes 

 from the south, but its direction is modified at every step, either by 

 mountain chains or by valleys. Its origin is still a subject of 

 discussion : according to some it originates in the Sahara, according 

 to others it originates in the Gulf of Mexico. It gives to the sky a 

 strangely-marked, peculiar, heavy, whitish aspect ; and the rain falls 

 on the second or third day following its appearance. 



" The wind arrives on the Mediterranean coast loaded with vapour; 

 it there encounters that immense calcareous semi-circular wall of the 

 Maritime Alps, and it scales their higher slopes ; but in consequence 

 of their covering of forests, and the great heat concentrated by them, 

 in doing so it only attains a higher temperature. It is rarely the 

 case that the moisture is condensed or precipitated on these countries 

 which it rapidly traverses ; but it cools by degrees as it mounts the 

 Maritime Alps, and on reaching the upper basin of the Var and its 

 affluents it deposits an enormous quantity of water ; then it continues 

 to advance northwards to French Comt6, before reaching which 

 latitude it has lost much of its force. 



" If a glance be cast over a map of the Southern Alps, it may be 

 observed that from mount Viso there part off great chains running 

 perceptibly from east to west ; the fcehn comes up the valleys of the 

 basin of the Var, or of the upper sources of the Durance, it strikes 

 upon the first chain parting from the col of the Pas-de-la-Cavale, or of 



2d 



