6 H. F. Blanford — Influence of Indian Forests on the 'Rainfall. [No. 1, 

 B. In unaffected areas. 



Sangor 



1866-75 



55-97 



1876-85 



40-62 



—15-35 



Damoh 



1867-75 



54-76 



1876-85 



46-82 



— 7-94 



Jubbulpore 



1866-75 



60-66 



1876-85 



56-28 



— 4-38 



Narsinghpur ... «., 



1866-75 



55-46 



1876-85 



50-40 



— 5-06 



Hosliangabad ... ... 



1866-75 



47-08 



1876-85 



57-73 



-f- 10-65 



Khandwa 



1867-75 



34-74 



1876-85 



33-32 



— 1-42 



Raipur ... 



1866-75 



51-59 



1876-85 



54-47 

 Mean 



+ 2-92 

 — 2-94 



The contrast, tlans shewn, is sufficiently striking ; but taken as 

 they stand, it can hardly be said that the figures do more than afford a 

 certain presumption in favour of the view that the difference shewn by 

 the two series of stations is to be attributed to the preservation of the 

 foresti. In the first place, as I shall shew elsewhere, the probable error 

 of a ten years' rainfall average of a station in the Central Provinces is 

 about 5 per cent., and this may be either in excess or defect. In the 

 extreme case of the errors being in opposite directions in the two decen- 

 nial periods compared, the greater part of the apparent increase of list 

 A would vanish. And, in the second place, the majority of the stations 

 in the second list lie to the north of the Satpura range, those of the first 

 list either on the range itself or to the south of it ; and, as this range 

 about coincides with the southern margin of the tract commonly followed 

 by the cyclonic storms of the summer monsoon, the distribution of the 

 rainfall might be much affected by the fact of a series of such storms 

 following a more southerly or more northerly path, or by the western 

 branch of the monsoon, which brings nearly the whole rainfall to the 

 region south of the Nerbudda valley, being in several years, relative- 

 ly to its normal average, stronger and more rainy than the eastern 

 branch, which contributes to the rainfall north of that river. 



But there is another way of dealing with the facts which will not 

 be open to such objection. Any effect really due to forest protection 

 must necessarily have been progressive. Some few years were passed 

 in inducing the jungle tribes to take to settled cultivation ; again, the 

 reproduction of the forest growth on the tracts formerly denuded is a 

 process requiring many years for its accomplishment ; and, finally, the 

 protection of the forests from destruction by annual fires in the dry 

 season has been steadily extended year by year. If, then, it should 

 appear, on comparing the rainfall of the affected tract in successive 

 years, that the increase has been steadily progressive and on the whole 

 in a degree commensurate with the average difference of the two decen- 

 nial periods above compared, the probability of such increase having 

 been brought about by the protection of the forests will be enormously 

 enhanced. 



