250 The Winds. 



to represent the daily revolution of the earth. A circular rim 

 pierced with holes is fastened to the globe, about its upper 

 pole ; and a few streams of ink are allowed to run from these 

 upon its surface, whilst the globe revolves. In a few seconds 

 the globe can be brought to rest, and the direction of the 

 streams can be examined. Each stream presents a curvilinear 

 line ; in general very oblique to the meridians, but at its centre 

 transverse to the equator, to which its upper and lower branches 

 are also symmetrical, and turned towards the east in the man- 

 ner of a Greek letter e. This simple experiment may very 

 well be taken to represent the real course of nature. The 

 streams in the upper half of the globe represent the trade 

 winds, which blow from the north-east in the northern hemi- 

 sphere, and from the south-east in the southern hemisphere of 

 the globe. At the equator they are exactly opposed to one 

 another, and blow due north and south, where the belt of 

 the " variables" is formed, as they are called, because they are 

 mixed at this place with westerly monsoons. The streams in 

 the lower half of the globe represent the anti-trade winds. 

 These return upon the same course as the trade winds, but in 

 the opposite direction to the point whence those set out, and 

 blow from south-west in the northern hemisphere, and from 

 north-west in the southern hemisphere of the earth. 



The anti-trade wind blows in summer upon the top of 

 the Peak of Teneriffe, while the trade wind sweeps its foot. 

 In winter the anti-trade wind reaches the ground about the 

 latitude of the Canary Isles, and in its contest with the trade 

 winds forms the " horse-latitudes " of the ocean, with rains as 

 copious as those at the equatorial calms. From this point to 

 the latitude of 50°, and upwards, the anti-trade is the 

 prevailing wind of the Atlantic Ocean, almost as surely as the 

 trades between the tropics. These winds are only constant on 

 the open oceans of the globe, for a reason that is easily ex- 

 plained. In the neighbourhood of continents they are replaced 

 by winds of a different character, called monsoons. 



The constant overflow, and demand of air at the equator 

 produces an equally regular supply, flowing north and south 

 towards the line. Obedient to the impulse of the wind, a 

 drift of surface-water inwards is produced, and a line of 

 greatest heat is thus established at the equator, whose position 

 hardly varies with the seasons. In this way the trade and 

 anti-trade winds acquire a cast, or set by which the uniformity 

 of their circulation is secured. 



Coming from latitudes where the velocity of rotation of the 

 earth's surface is less swift, light air currents quickly take up 

 the velocity of rotation of the circles of latitude over which 

 they pass. It is different with the surface drift of water. 



