WIND 659 bia. The many fables and exaggerated ao counts of ancient travellers have been mate- rially modified by exact observations of recent investigators, from which it appears that this is a strong, hot, dry wind drawn from the heated interior of the continent; it is fre- quently accompanied by sand clouds or sand pillars, and its deadly qualities, if such it has, are simply the result of the oppressive heat and the very fine dust. Similar hot winds pre- vail in Egypt in May and June, and are there known as the khamsin. Of the dry winds that flow out from the interior of continents or down the slopes of mountain ranges, some are cold, others warm. Thus the northers of Texas are due to a thin surface layer of dry air, which as it flows from the Kocky mountains, from Kansas, and from Minnesota, southward or southeastward, continually loses by radiation the heat it receives from the sun, and, under- flowing the warmer, moister air of the gulf of Mexico, rushes over the smooth surface of the water with thrice the velocity that is observed in the interior of the continent. On the W. coast of Africa the dry E. and N. E. winds are known as .the harmattan; these are cooling on account of their extreme dryness, and in every detail offer a parallel to the northers, except that they have a higher temperature, and are frequently accompanied by sand, which is rarely or never found in Texas. The dry cold wind flowing southward from the Hima-- laya over India is there known as the tereno. In South America, from Patagonia to Brazil, there occurs a similar dry wind known as the pampero, which flows almost uninterruptedly from the Andes E. and S. E. to the Atlantic. Similar strong, cold, dry winds flowing from central Europe southward over the Adriatic and Black seas are known there as bora (with which the curoclydon of St. Paul may be iden- tical). At Malta the N. E. wind is the gregale. In southern Arabia the cold N. N. W. wind of winter is the Mat. Perhaps the most thor- oughly desiccated of any of the winds that have been observed as yet are the S. E. or puna winds of eastern Peru and the N. or buran of Thibet, on which table lands cold dry gales pre- vail, which are highly disagreeable to human beings and even to animals. Similar danger- ous gales are called purgas in Labrador, guxen in Switzerland, gallegos in Spain, and tour- mentes in France. The dry east winds of spring in Great Britain have been from time imme- morial proverbial for their injurious effects on delicate constitutions, and the very dry west winds of the United States E. of the Kocky mountains contribute, it is very plausibly urged, to the nervous temperament of the nation. The prevailing winds being westerly both in Europe and North America, it follows that the former continent enjoys a much moister and more agreeable climate, and one much less pro- vocative of nervous diseases. Of the names given to certain storm winds as such, we may mention the levante, a strong east wind in the eastern part of the Mediterranean ; the hurri- cane, a term derived from the ouracan of the Larib Indians, and applied by them to the ter- rific storms of the West Indies; the typhoon a term of most ancient origin, nominally de- rived from the Chinese toe-fun as applied to the great storms of the Pacific ocean, but cu- riously related to the name Typhon applied by the Egyptians and Greeks to a dreaded di- vinity ; finally, the tornado, a term applied in America to destructive winds that rush in nar- row paths over long belts of territory, accom- panied by whirling clouds and heavy rain or hail. The name tornado (Port, tornar, Sp. tor- near, to turn) was originally given by the Pen- insular navigators to the violent local storms that occur a short distance off the coast of Africa, and was subsequently applied very properly by them to the similar violent storms of our southern states. Less perfectly devel- oped but still destructive tornadoes occur in all parts of the United States. Of local Amer- ican terms we record only the expressive name " blizzard " given in the states W. of the Mis- sissippi river to the blinding storms of sleet or snow and high N. wind that suddenly follow warm spring-like days in winter and early spring. Similar storms of similar origin occur in the steppes of southern Eussia, where they are known as ttiuga. In the Sandwich islands the S. wind preceding a hurricane and interrupt- ing the regular N. E. trades is called the Icona. On the W. side of the Crossfell range of hills in England are formed during easterly winds and previous to rains two peculiar clouds, from one to five miles apart, under which it is calm, while between them is felt a strong east wind locally known as the "helm wind of the Cross- fell." 8. Our sketch of the winds would be imperfect without enumerating the remarkable areas of variable light winds and calms that constitute an important feature in terrestrial meteorology. These calms are sufficiently de- fined by their names : 1, the calms of the tropic of Capricorn ; 2, the equatorial belt of calms, or the doldrums; 3, the calms of the tropic of Can- cer, or the horse latitudes. 9. The explanation of the cause of the general system of terrestrial winds has been already given in METEOROLOGY. But besides the winds caused by differences of barometric pressure and of density, there are a few phenomena of occasional and minor importance, due to other causes ; for instance, the gusts of wind that precede by a few minutes heavy local showers of rain and hail, t result from the mechanical action of the falling'drops, which communicate a part of their motion to the air ; this, pressing down against the ground, is forced outward, so that on the edge of a rainy region the wind appears to blow from the rain. The existence of this wind complicates considerably the phenomena of local thunder storms, and has even misled some authorities
- nto erroneous explanations of their origin and
structure. Pressure of the Wind. Owing to
- heir great importance in relation to innumer-
