1887.] H. F. Blanford— Influence of Indian Forests. 85 



of rivers, such as the Hooghly. A fall description of the construction of 

 the bottle hydrometer, and the author's simple plan for making the 

 counterbalancing wire weights, are given in the paper. 



The paper will be published in the Journal, Part II for 1887. 



2. On the influence of Indian Forests on the Rainfall. — By H. F. 

 Blanford, F. R. S., Meteorological Reporter to the Government of India. 



The President made the following remarks on the above paper : — 

 Whatever doubt there may be as to the direct influence of forests in the 

 production of rain, there can be none in regard to their effect upon the 

 distribution of the rain-fall by means of springs and streams. This is 

 clearly shown in the recent report of the ' Division of Forestry ' attached 

 to the United States Department of Agriculture. It is there shown that 

 the removal of forests from the neighbourhood of streams not only lessens 

 the whole amount of water flowing in their channels, but renders its 

 flow much more irregular than before. In the case of the smaller 

 streams, where the forests adjacent to them or in which they have 

 their head springs have been cut off, the streams have been often so 

 reduced as, at certain seasons of the year, almost to disappear. And, 

 in the case of streams, whether large or small, the result has been to 

 produce floods when the snows melt in spring-time, or after heavy rains, 

 to be followed by a greatly diminshed flow of water afterwards, espe- 

 cially in those seasons of the year when rains are least frequent and 

 copious. These effects of the denudation of forest areas occur not only 

 in the Eastern States of the United States but along the Danube, Elbe, 

 Oder and Vistula ; but it has also been shown that the reafforesting of 

 denuded tracts restores the even flow of water at all times and mitigates 

 the excessive flow in times of floods. 



The American Forest Department consider that nothing has been 

 better settled than that the forests are the great regulators of the dis- 

 tribution of the water precipitated from the clouds, and consequently of 

 the flow of streams. By their shade, and by the obstruction which they 

 offer to sweeping winds, they lessen the evaporation which would other- 

 wise speedily carry off from the ground much of the rainfall, while the 

 loose spongy soil, formed by the accumulation of their fallen leaves, 

 absorbs the water precipitated from the sky or produced by the melting 

 of the winter's snow, and causes it to flow off gradually into the channels 

 of the streams, instead of flooding them at once.' As to the direct in- 

 fluence of forests in producing rain or increasing its amount in their 

 immediate vicinity and their consequent favourable effect upon agricul- 

 ture and the supply of water for springs and streams, Mr, Blanford's 



