THE SWISS " FCEIIN." 263 



and could not explain the sudden gloom which had invaded the 

 atmosphere.* 



In Sicily and in the south of Italy a warm wind occasionally 

 blows from the south, which is considered as a sort of simoon, and is 

 saturated with moisture in passing over the Mediterranean ; this is the 

 scirocco. Usually it is not very rapid, and its gusts are interrupted 

 by stilling calms ; the surface of the water is hardly agitated, a mist 

 of vapours broods on the horizon, and the sun hides itself behind 

 a veil of whitish clouds. Under the enervating influence of this wind 

 from the south, all exertion becomes painful; but still the terrible 

 phenomena, which occur during the simoon, have never to be 

 dreaded. 



In the Alps of Switzerland the south wind is known under the 

 name of foehn, a word derived from favonius, the southern wind 

 of the Romans. What is, then, the origin of this current? Has 

 it originated in the Sahara, as Messrs. Desor, Martins, and Escher von 

 der Linth believe, and has its burning breath first served to melt the 

 ancient glaciers of the Alps ? Or is it simply a counter trade- wind 

 descended from the heights of the atmosphere, and does it come from 

 the Atlantic and the Caribbean Sea, as Dove asserts ? Would not 

 the moisture which it brings tend to enlarge the vast rivers of 

 ice ? The latter seems probable ; but however it may be, the foehn 

 frequently changes' its course, and whether or not it is a continua- 

 tion of the Mediterranean scirocco, the inequalities in the relief of 

 the mountains modify its character singularly. In rising over the 

 slopes, the air expands more and more in consequence of the lesser 

 atmospheric pressure, and it loses a great quantity of heat; from- 

 the warm wind, which it was at the foot of the mountain, the foehn 

 becomes a cold current. The ridge once crossed, the aerial mass, 

 which descends again towards the plains, is gradually compressed 

 by the upper strata, and the quantity of caloric, which had disap- 

 peared because of the expansion, is reproduced ; the cold wind of the 

 summit is heated again to blow in the valleys. This is a remark- 

 able phenomenon in the mountains which separate Yalais from 

 Piedmont and Lombardy. From being very warm at the entrance 

 to the Italian gorges of the Alps, the atmospheric current from 

 the south is cooled by from 35 to 55 degrees in passing over 

 Mont Eosa ; it lets fall rain and snow in abundance ; then, after 

 having descended again on the opposite slopes, it brings to the 



* A Yearns Travel in Central Arabia. 2 vols. 



