348 Dr George Buist on the 



the storms which then prevail. Flowing back again from 

 the coasts of India, where they are now in excess, to those of 

 Africa, where they suffer from perpetual drainage, the same 

 round of operations goes on continually ; and the sea, with all 

 its estuaries and its inlets, retains the same limit, and 

 nearly the same constitution, for unnumbered ages. A like 

 check prevents on shore the extreme heating and desiccation 

 from which the ground would otherwise suffer. The earth is 

 a bad conductor of heat ; the rays of the sun which enter its 

 surface, and raise the temperature to 100 or 150°, scarcely 

 penetrate a foot into the ground ; a little way beneath, the 

 warmth of the soil is nearly the same night and day. The 

 moisture which is there preserved free from the influence 

 of currents of air, is never raised into vapour ; so soonas the 

 upper stratum of earth becomes thoroughly dried, capillary 

 action, by means of which all excess of water was withdrawn, 

 ceases ; and even under the heats of the tropics, the soil 

 two feet down will be found on the approach of the rains 

 sufficiently moist for the nourishment of plants. The 

 splendid flowers and vigorous foliage which burst forth in 

 May, when the parched soil would lead us to look for nothing 

 but sterility, need in no way surprise us ; fountains of water 

 boundless in extent, and limited in depth by the thickness of 

 the soil which contains them have been set aside, and sealed 

 up for their use, beyond the reach of those thirsty winds or 

 burning rays which are suffered only to carry off the liquid 

 w r hich is superfluous and would be pernicious if left, removing 

 it to other lands where its agency is required, or treasuring it 

 up in the crystal vault of the firmament, as the material of 

 clouds and dew, — and the source, when the fitting season 

 comes round again, of those deluges of rain which provide for 

 the wants of the year. 



Such are some of the examples which may be supplied of 

 general laws operating over nearly the whole surface of the 

 terraqueous globe. Amongst the local provisions ancillary to 

 these, are the monsoons of India and the land and sea-breezes 

 prevalent throughout the tropical coasts. When a promon- 

 tory such as that of Hindostan intrudes into the region of the 

 trade-winds, the continuous western current is interrupted, 

 and in its room appear alternating currents from the north- 



