204 PHYSICS. 
identical ; samum, also simum, semum, simoom, or samiel (poisonous wind), 
is the name of this wind in Arabia, Persia, and in most countries of the east. 
It is called chamsin in Egypt, and harmattan in the negro tongue. The 
term chamsin, meaning fifty, comes from its blowing generally for the fifty 
days from April 27 to June 18, although sometimes the vernal equinox 
occurs in the middle of its period. These winds show themselves in greatest 
violence in treeless, sandy deserts, their distinguishing character being heat 
and dryness. A darkening of the horizon is the surest precursor of the 
simoom ; when it actually arrives, the clear heaven vanishes, the sun loses 
his lustre, the air is filled with particles of sand, and all nature exhibits signs 
of the greatest disquiet. The heat becomes much more oppressive during 
the storm, particularly when columns of sand are carried along by the 
current. That the wind in itself is deadly, or at least injurious to the health, 
seems to be unfounded; at any rate the narrations of many of the earlier 
travellers appear to have been highly overcharged. Even the assertion that 
men and camels cast themselves on the ground at the approach of the storm, 
burying their faces in the sand, and thus await the passage of the blast over 
them, appears to belong to the class of fables; so much is true that the 
Arabians, during these storms, not unfrequently veil their faces and kneel 
down behind their camels. In western Asia, particularly in Arabia Petra, 
and the deserts between Bagdad, Bassora, Aleppo, and Mecca, the simoom 
blows only during the months of June, July, and August, being most violent 
in July; it presents itself only by day, and on land, lasting at most only a 
few hours. With regard to the direction of these winds, they come on the 
borders of the desert from the following quarters: in lower Egypt from the 
south-west, in Mecca from the east, in Surat from the north, in Bassora 
trom the north-west, in Bagdad from the west, in Syria from the south-east, 
&c. On the western coast of Africa, particularly in Senegambia, the wind 
is called harmattan ; it there is injurious only te vegetation, being directly 
conducive to health by driving away fevers and other diseases. The cham- 
sin in Egypt generally lasts from two to three days. 
The sirocco of Italy, and the solano of southern Spain, are probably only 
continuations of the harmattan blowing in Africa, which loses its dryness in 
passing over Mount Atlas and the Mediterranean sea, retaining, however, 
its heat and relaxing properties. The influence of the sirocco, principally 
exerted in Sicily and Naples, and the isle of Malta, sometimes extends to 
southern Germany (the Tyrol and Steyermark). On the island of Madeira 
it blows as an east-south-east wind ; it is there remarkably dry, accompanied 
by cloudless skies, and lasting about three days. The solano in Spain is 
likewise remarkable for its heat. 
The Féhn which comes down from the Alps into some of the valleys of 
Switzerland is also supposed to be a continuation of the sirocco. It isa 
south wind, exceeding all other winds of the country in violence, before 
whose occurrence the sun becomes dimmed, and a haze forms over the sky. 
Shortly before the beginning of the fohn a north wind called féhn-bise 
generally blows in the higher regions. When the fohn approaches, plants 
wither, animals become restless, and the inhabitants experience a sensation 
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