DISTRIBUTION OF RAINFALL. 279 



low-lying lands or places near the coast. And when one observes the 

 distribution of the rainfall over the ramifications of the same valley, 

 the phenomena become still more interesting. The basin of the 

 Seine is particularly suited for this study, since it is regular in form, 

 lai'gely open to pluvial winds, and more especially since M. Belgrand, 

 who has explored it in its every part, has made us acquainted with 

 his scientific investigations.* 



" Near the sea, at the lighthouse of Fatonville, there falls annually 

 799 millimetres of rain. From this point to the valley of the Oise 

 the plateau maintains perceptibly its level ; in consequence of this 

 the quantity of the rainfall diminishes in proportion as the pluvial 

 current advances from the sea. The average sinks to 580 milli- 

 metres in the valley D'Oise, and to 575 '6 millimetres at Paris ; but 

 it re-increases from that point as the land itself rises : it amounts to 

 656 millimetres at Hirson ; towards the Ardennes, at the altitude of 

 196 metres ; and to 1570 millimfeti-es at the Settons, on the height of 

 the Morvan, where the altitude is 596 metres. 



" It is remarked that it rains more in valleys than on elevated 

 plains, because the atmospheric current follows by preference the 

 deep depressions which cut up the plateaux, in the same way as on 

 the flat bottom of a valley levelled by an inundation, the current by 

 its tumultuous waves still marks out distinctly the line of the old 



" But M. Belgrand, however, has established as a fact that the 

 pluvial current does not go up iudifierently every valley ; it passes 

 bye the valley D'Oise, and ascends by preference the valley of the 

 Seine, and by that of the Yonne, which in going up from Montereau 

 is a direct continuation of the first. 



" Even at Paris the hill of Montmartre divides this current, which 

 bifurcates as does a river around a pier of a bridge ; the pluvial 

 wind passes by preference behind the hill, and La Villette receives 

 more rain than does Paris. Thus each valley receives more rain in 

 proportion as it is set towards the atmospheric current which brings 

 the rain." 



Other observations not less interesting -are adduced by M. Cezanne, 

 illustrative of an influence on the distribution of the rainfall being 

 exercised by the contour of a country. ' 



In illustration of the same thing, M. Eaulin, Frofesseur <X la 



* Belgrani ; Regime dc la pluie dans le basin de la Seine [annales des Fonts 

 et Chaui6es. 1865). 



