114 THE ORIGIN Of 



diminishing, and the climate otherwise altering in consequence 

 of the clearance of the forests ; while on the other hand, under 

 the beneficial influence of a largely increased cultivation of the 

 palm in Egypt, rain is annually becoming more frequent. 

 Lakes are cited in what was formerly Spanish America (that of 

 Nicaragua, if we mistake not, is one) whose water supply 

 (derived, of course, from atmospheric sources,) had been so 

 largely diminished, owing to the denudation of the country 

 under the Spanish Regime, as to contract their areas, and leave 

 large tracts of their shores dry ; which, now that the vegetation 

 is again restored, are once more covered by their waters." 



The reason why trees attract the rain is, Sir John says : 

 " The foliage of the trees defends the soil beneath and around 

 them from the sun's direct rays, and disperses their heat in the 

 air, to be carried away by winds, and thus prevents the ground 

 from being heated in the summer ; while on the other hand, a 

 heated surface soil, reacts by its radiation on the clouds as they 

 pass over it, and thus prevents many a refreshing shower 

 which they would otherwise deposit, or disperses them 

 altogether." 



We confess we cannot understand, neither does he explain, 

 why a soil that is not heated will attract rain, or "vice versa." 

 How much simpler would it not be to say, that well wooded 

 districts attract or produce rain, because there is always an 

 excess of vegetable gases around them, which are thus always 

 ready to combine with any mineral winds that may be blown 

 over them. While on a barren moor which has no sufficient 

 supply of oxygen, reciprocation seldom takes place. 



H Drainage " Herschell also says, " is bad, for it cuts off a 



