14 H. F. Blanford — hifneiice of Indian Forests on the Rainfall. [No. 1, 



above amounts, in inverse proportion to the distances of the two 

 stations, the average of the same 17 years would be 14*85 inches. 

 It is actually 15* 76 ins., or nearly 1 inch above the computed pro- 

 portion. 



I am far from considering this result as conclusive on the point 

 at issue. In some years, the deviation from the mean proportions is 

 very large, and the average of the last three years (which, in this part 

 of the Punjab, have been characterized by a remarkably low rainfall) 

 shows that the Vahn rainfall has been almost exactly in the inverse ratio 

 of the relative distances of the two outer stations. Still, the evidence, 

 so far as it goes, favours the idea that the forest increases the rainfall. 



The general conclusion to be drawn from the facts set forth in 

 the foregoing pages is that, while no one of the instances cited fulfils 

 the requirements of scientific proof, the tendency of the evidence they 

 afford is uniformly favourable to the idea that the presence of forest 

 increases the rainfall. 



The evidence is of three kinds. First, we have that of a large 

 province some five-sixths of which have always been a forest wilderness, 

 but in which, for the first ten years of the pei'iod of registration, the forest 

 growth was greatly devastated ; partly by ddhya cultivation, which 

 completely destroyed the forest for the time being, whenever it was 

 carried on, and partly by annual forest fires, which destroyed the 

 under-growth and injured the larger trees. For the next ten years, 

 these destructive operations were suppressed and the visible result is 

 a forest growth of such vigour and luxuriance as to attract the atten- 

 tion of the Inspector- General, when on his tour of inspection, to the 

 question of its probable effect on the rainfall. During these last ten 

 years the rainfall of the province has progessively increased until it 

 would appear to amount to 20 per cent, more than the average of the 

 first ten years. 



The second instance is that of two pairs of comparative obser- 

 vatories, established on the Ebermeyer plan, in near proximity to each 

 other on the boundary of a protected forest ; one of each pair being 

 within, the other without the forest, on open ground. Notwithstanding 

 their proximity, in most months the outer observatories shew a slight 

 excess over the inner. At each observatory there are two gauges ; one 

 at 60 feet above the ground, the other on the ground ; and both afford 

 consistent results. In the case of one pair of observatories, the total 

 of 18 months' register shew an excess in the inner high level gauge of 4 

 per cent., in the lower of two per cent. In the case of the other pair, the 

 registers of 12 months only shew an inappreciable net difference of 

 the totals, although, in most months, the forest-gauges shew a slightly 

 enhanced fall. 



