104 



A HISTORY OF 



this reason, our easterly winds that blow 

 from the continent, are dry, compared with 

 those that blow from the surface of the ocean, 

 with which we are surrounded on every 

 other quarter. 



In general the winds are more boisterous 

 in spring and autumn than at other seasons : 

 for that being the time of high tides, the sea 

 may communicate a part of its motions to the 

 winds. The sun and moon, also, which then 

 have a greater effect upon the waters, may 

 also have some influence upon the winds : for, 

 there being a great body of air surrounding 

 the globe, which, if condensed into water, 

 would cover it to the depth of thirty-two feet, 

 it is evident that the sun and moon will, to a 

 proportionable degree, affect the atmosphere, 

 and make a tide of air. This tide will be 

 scarcely perceivable, indeed ; but, without 

 doubt, it actually exists; and may contribute 

 to increase the vernal and autumnal storms, 

 which are then known to prevail. 



Upon narrowing the passage through which 

 the air is driven, both the density and the 

 swiftness of the wind is increased. For, as 

 currents of water flow with greater force and 

 rapidity by narrowing their channels ; so also 

 will a current of air, driven through a con- 

 tracted space, grow more violent and irresis- 

 tible. Hence we find those dreadful storms 

 that prevail in the defiles of mountains, 

 where the wind, pushing from behind through 

 a narrow channel, at once increases in speed 

 and density, levelling, or tearing up, every 

 obstacle that rises to obstruct its passage. 



Winds reflected from the sides of moun- 

 tains and towers, are often found to be more 

 forceful than those in direct progression. 

 This we frequently perceive near lofty build- 

 ings, such as churches or steeples, where 

 winds are generally known to prevail, and 

 that much more powerfully than at some 

 distance. The air, in this case, by striking 

 against the side of the building, acquires ad- 

 ditional density, and, therefore, blows with 

 more force. 



These differing degrees of density, which 

 the air is found to possess, sufficiently show 

 that the force of the winds do not depend 

 upon their velocity alone ; so that those in- 

 struments called anemometers, which are made 

 to measure the velocity of the wind, will by 



! no means give us certain information of the 

 j force of the storm. In order to estimate this 

 with exactness, we ought to know its density ; 

 I which also these are not calculated to dis- 

 : cover. For this reason we often see storms, 

 ! with very powerful effects, that do not seem to 

 I show any great speed; and, on the contrary, we 

 j see these wind-measurers go round with great 

 ! swiftness, when scarcely any damage has fol- 

 i lowed from the storm. 



Such is the nature and the inconstancy of 

 the irregular winds, with which we are best 

 acquainted. But their effects are much more 

 formidable in those climates near the tropics, 

 where they are often found to break in upon 

 the steady course of the trade-winds, and to 

 mark their passage with destruction. With 

 us the tempest is but rarely known, and its 

 ravages are registered as an uncommon cala- 

 mity ; but in the countries that lie between 

 the tropics, and for a good space beyond them, 

 its visits are frequent, and its effects are an- 

 ticipated. In these regions the winds vary 

 their terrors ; sometimes involving all things 

 in a suffocating heat ; sometimes mixing all 

 the elements of fire, air, earth, and water, to- 

 gether ; sometimes, with a momentary swift- 

 ness, passing over the face of the country, and 

 destroying all things in their passage; and 

 sometimes raising whole sandy deserts in one 

 country, to deposite them upon some other. 

 We have little reason, therefore, to envy 

 these climates the luxuriance of their soil, or 

 the brightness of their skies. Our own muddy 

 atmosphere, that wraps us round in obscurity, 

 though it fails to gild our prospects with sun- 

 shine, or our groves with fruitage, neverthe- 

 less answers the call of industry. They may 

 boast of a plentiful, but precarious, harvest ; 

 while, with us, the labourer toils in a certain 

 expectation of a moderate, but a happy re- 

 turn. 



In Egypt, a a kingdom so noted for its fer- 

 tility and the brightness of its atmosphere, 

 during summer, the south winds are so hot, 

 that they almost stop respiration; besides 

 which, they are charged with such quantities 

 of sand, that they sometimes darken the air, 

 as with a thick cloud. These sands are so 

 fine, and driven with such violence, that they 



Buflfon, vol. ii. p. 258. 



