DISTRIBUTION OF RAINFALL, 277 



" Under the tropics, where prevail the trade-winds blowing from 

 the east, the lands which incline towards the east are inundated with 

 torrential rains : thus is it on the coast of Mozambique, and in the 

 basin of the Amazon. On the contrary, it almost never rains on the 

 western slope of the Andes. It is said that thunder has not been 

 heard at Lima three times in as many centuries.* 



" In the Indian peninsula the eastern coast, or that of Coromandel, 

 is watered by the North-east Monsoon ; and the west coast, or that of 

 Malabar, by the South-west Monsoon.t 



" When, after having climbed the slope of a mountain, the atmos- 

 pheric current, greatly relieved of its load, comes upon a plateau, it 

 freely expands ; but its lowest layer, being in contact with the earth, 

 is alone reduced to a lower temperature. From which it comes to 

 pass that, from the same wind, a plateau, though more elevated, 

 receives less rain than the ascending slope, but receives more than 

 does the descending slope beyond. 



" The summit of the elevation which separates the Ocean from the 

 Mediterranean supplies the following table : — | 



" From this table it may be seen that the slopes receive a little 

 more rain than do the summits, and if it be borne in mind that the 

 summit gets rain — now from the east wind, now from the west 

 wind, — while Carcassonne, for example, does not receive it except 

 by the east wind, it is beyond a doubt that the summit receives 

 less rain from the same wind than is received by the two slopes 

 which are ascended by the pluvial current. 



" On a very interesting hy^tographic chart, prepared by M. Delesse, 

 Ingenieur en chef des mines\\ it is seen that the plateaux of La Beauce 

 and of La Brie, subject to the influence of the west wind alone, present 

 a very manifest minimum. There falls at Chartres 540 millimetres, at 

 Meaux 400 millimetres of rain annuaUy. 



" La Burgogne forms, as is known, a basin which stretches itself 



* Eevieu : Theorie de la pluU [Annuaire de la SocUti m^teorologique de 



France, (1866) tome XIV.) 



■f Lamairesse (annales despont et Chaussees, October 1869). 



X Raulin : Ohseroations Pluviometriques. 



D Deleste : Distribution de la Pluie en France (Bulletin de la 8oci6t6 de 



geographie dm, 1868.) 



