June] SMALLWOOD — ON RAIN. 185 



less humid and consequently heavier currents from beneath, 

 form together the nimbus (or rain cloud). These induce a 

 change in temperature and electrical action, conditions neces- 

 sary to produce rain. This is carried by clouds and currents 

 of wind and distributed over the lands of our continents, thus 

 watering the earth, supplying vegetation, and the various wants 

 of mankind and returning again by the rivers to the sea. From 

 the surface of the ocean pure aqueous vapours are constantly 

 ascending to supply the unceasing requirements of the organic 

 and inorganic world. 



Rain-clouds are attracted to certain localities more than to 

 others, for it was shewn that at Ulleswater (England) the 

 great heat of 1866 caused a great increase in the amount of rain, 

 owing to its condensation by the mountains in that district. 

 But beyond the formation of the surface of our globe, there are 

 other conditions which supply natural conductors, such as the 

 pointed extremities of the leaves of trees and of plants. May 

 not our primaeval forests have given rise to a different meteoro- 

 logical condition of a former world ? The great coal formations 

 may be taken as an example in illustration of this. 



Many countries have been made sterile by cutting down 

 indiscriminately the whole of the trees. Such, indeed, is actually 

 the case in the recent deserts of Syria, Chaldea and Barbary. 

 The '■'■Oases" of the desert are nothing more than a few trees 

 purposely left as a shade for the weary traveller. 



The value of several estates in the West Indies has been 

 greatly diminished by the cutting down of the trees upon them, 

 and the rain fall over large regions of our own continent is much 

 diminishing, 'owing, no doubt, to the large and extensive clear- 

 ances of our forest ; while on the other hand, the rain fall in the 

 Upper Province of Egypt has been increased tenfold by the 

 planting of twenty millions of trees by Mehemet Ali. 



Until two years ago rain in that Province was unknown ; 

 but in twelve months ending April last there were actually 14i 

 days on which rain fell, and later there fell a heavy shower — 

 a phenomenon which the oldest Arab had never witnessed. 

 Here we see rain returning to the desert on restoring the trees. 



Ic Spanish America, lakes have had their area diminished and 

 their shores dried from the general removal of the trees by the 

 Spaniards ; but now that cultivation has been resumed by the 

 enterprising Americans, these lakes are being again filled up 



TOL. lY. 1^ No. 2. 



