September, 1909.] 2 



tiou of the leaves." I have no hesitation 

 in giving my opinion that, speaking 

 generally, there are no underground sup- 



Elies available for forest growth which 

 ave not been derived from the rainfall 

 of the few years immediately preceding ; 

 and that such supplies are, in com- 

 parison with the annual supply, small. 

 I see no reason to modify the conclusion 

 to which I came in my previous letter 

 of the forces which change the hygros- 

 copic condition of the soil, the chief are 

 gravity, capillarity and friction : the 

 two latter retard but do not neutralise 

 the action of the former. Water cannot 

 disobey the law of gravity under, any 

 more than on, the surface of the land, 

 and were the rainfall to cease, the water 

 underground must find its way even- 

 tually to sea-level, and consequently the 

 water underground above sea-level must 

 have been derived from that portion of 

 the rainfall which has not evaporated 

 from the land, or flowed away to the 

 sea. No matter, therefore, how large the 

 underground supplies may be, the land 

 cannot lose more annually than it 

 receives ; and hence the evaporation from 

 a forest area cannot be greater than that 

 portion of the rainfall which is not 

 evaporated from the surface and sinks 

 into the soil. 



It may be of assistance to endeavour 

 to make some estimate of the under- 

 ground supplies of water. The quanti- 

 ties which it is generally assumed in 

 India remain in the soil with a rain- 

 fall of 60, 30, and 20 inches, are 30, 22 and 

 16| inches respectively. It will be noted 

 that the proportion increases largely as 

 the rainfall decreases. I have not been 

 able to find a reliable estimate of how 

 much of this is evaporated before it 

 sinks into the soil, but will assume it is 

 not much different from 10 inches. 

 Leaving out of account the favoured 

 localities immediately bordering on 

 rivers and reservoirs, the area of which 

 is relatively very small, the effect of a 

 succession of dry years, indeed very 

 frequently of two or even one dry 

 year, is the drying up of even 

 deep wells, and widespread destruc- 

 tion to the forests, in which the 

 deepest rooted species are not spared- 

 This indicates that the underground 

 supplies available cannot be much 

 larger than the yield on the rainfall of 

 at most a very few years, or, in view of 

 the above figures, more than a few feet. 

 Were the operation from a forest area 

 many times larger than that from a 

 water surface, a loss of a few inches in 

 the supply to the soil would have no 

 material effect. 



I have not been able to find very 

 detailed information on the subject; 



Miscellaneous 



but it would appear to be the case that 

 generally throughout India, in those 

 tracts where well irrigation is highly 

 developed, and where the subsoil water- 

 supply is not increased by canals, no 

 matter what may be the depth and 

 number of the wells, or nature of the 

 soil, or nature of the crops, in no place 

 where the area irrigated from wella is 

 large compared with the unirrigated 

 area is the average amount drawn from 

 the wells equal to the average amount 

 of rainfall retained in the soil. This is 

 in accordance with the theory above 

 given, and is indeed a deduction from 

 it. One conclusion is that, as the roots 

 of trees cannot draw up more than the 

 wells can supply, the evaporation from 

 a forest area is less than the amount of 

 rainfall retained in the soil. Another 

 conclusion, though one not germane to 

 the present subject, is that in tracts 

 where the rainfall is small, and where, 

 as would be expected, the wells are in- 

 variably deep, it is impossible to protect 

 against famine by means of wells alone 

 more than a fraction of the whole area, 

 a fraction that will decrease with the 

 rainfall. 



These are some of the reasons which 

 confirm me in the conclusion to which I 

 came in my previous letter, that over 

 by far the greater pait of India, or for 

 that matter of the globe, the evaporation 

 from a forest area must be considerably 

 less than from an equal area of water. 



E. BACHELOR, i.c.s. 



CO-OPERATIVE CREDIT IN BENGAL. 



(From the Indian Agriculturist, Vol. 

 XXXIII., No. 11, November 2, 1 1 j09. ) 



In some respects the most interesting 

 movement in Bengal at the present time 

 is that, which is gradually popularising 

 the idea of co-operative credit and is 

 thus preparing the way for the emanci- 

 pation of the cultivator from the system 

 of usury that now cripples his energies. 

 The growth of Co-operative Societies in 

 this Province during the twelve months 

 ending the 30th June last has been most 

 encouraging, and Mr. Gourlay has reason 

 to feel gratified at the promising results 

 of the reform to which he has devoted 

 so much energy and enthusiasm. Of 

 course we are still in the day of small 

 things. The total share capital of the 

 urban societies is only Rs. 19,000, and 

 the assets even of the rural societies is 

 little more than £13,000. These are 

 modest figures for a Province which 

 has 50 million inhabitants. But the 

 significant fact at present is not the 



