460 L. Rogers — HelationsTiip of the water-supply, water -logging [No. 4, 



approximately the normal figure for this part of Lower Bengal. It 

 would, therefore, appear that the east bank of the Hooghly is excep- 

 tionally healthy, although some of the Municipalities in the low-lying 

 tract a little to the east of the river show very high spleen-rates, more 

 especially North Dam Dum and the portion of South Barrackpore to 

 the east of the railway, whose figures are 68 and 56 per cent, respec- 

 tively. It may also be at once mentioned that last year, namely, 1899, 

 was an exceptionally feverish one on account of the excess and uneven 

 distribution of the rainfall. 



On looking more closely at the figures it will be observed that there 

 is one marked exception to the rule above pointed out, for Maniktolla, 

 although situated away from the river-bank and on extremely low-lying 

 and water-logged land, has, nevertheless, the second lowest spleen-rate; 

 an exception which has proved to be the key to a very important factor 

 in the causation of the variations of the spleen-rate in the tract under 

 consideration. The only ground on which the low spleen-rate of 

 Maniktolla can be accounted for is the enjoyment by this advanced 

 Municipality of a good filtered water supply. It is also worthy of note 

 that Chitpore-Cossipore, which has the lowest rate of all, namely, 11*2, 

 has the double advantage of a filtered water supply and a situation on 

 the east bank of the Hooghly. That these are the true reasons of its 

 marked immunity is shown by the fact that the average rate of the two 

 western Wards is only 7 '4, while that of the two easteruly Wards, 

 situated from one to two miles from the river, is 14' 7, that is almost 

 the same as that of Maniktolla. The density of the population of 

 Chitpore, and consequent smaller number of tanks, etc., may also be a 

 slight factor in its healthiness, but the details to be given immediately 

 with regard to the spleen-rates of different parts of Maniktolla and 

 other places show that this is not a factor of any great importance, but 

 on the other hand they will prove conclusively the intimate relationship 

 between a filtered water-supply and a low spleen rate, but as this point 

 is one of the utmost practical importance it will be necessary to go 

 somewhat into detail with regard to the spleen-rates of different Wards 

 of the same Municipalities, more especially of those parts of which 

 are being supplied with good water by mills situated within their 

 boundaries. At the same time the data with regard to the ground water- 

 levels will be given, so that the question of water-logging can also be 

 discussed. 



Ward variations in the spleen-rates. 1. Maniktolla. — This 

 Municipality, as will be evident from the accompanying map, is situated 

 between the Circular and the New Cut Canals, and this area is so flat 

 that there is only a fall of some eight feet from west to east in a 

 distance of two miles. Its drainage is dependant on channels by the 



