92 Capt. L. Rogers — Malaria North of Calcutta. [July, 



exceptionally healthy for Lower Bengal, but the reason remains to be 

 found. 



One very marked exception will be found to the above rule, 

 namely, that Maniktolla although at some distance from the river, yet 

 has a very low spleen rate, the lowest of all the thirteen nreas 

 except Chitpore-Cossipore, facts which can only be explained as being 

 due to these two municipalities being the only ones of the lot which 

 have a full filtered water supply. Moreover, this low rate occurs in 

 spite of these two places being the most water-logged in the whole 

 area, their ground water levels being but from 4 to 5 feet below the 

 surface in the dry season, and from 1 to 2 feet down only during 

 the rains. 



This result was somewhat surprising in view of recent work on 

 malaria, so advantage was taken of the fact tliat certain wards of some 

 of the municipalities were partially supplied with filtered water from 

 standpipes provided by ceitain of the mills within them to examine 

 more closely into the question. The result was ample confirmation of 

 the relationship of the water supply to the spleen rate, illustrative 

 examples of which are as follows. Naihati is divided up into five wards, 

 beginning from the south. The first three are mainly inhabited near 

 the river, and their spleen rates are 19"5, 10"8 and J 9 respectively. The 

 very low rate of Ward II coincides with a partial filtered water supply 

 from a mill, which is the only difference between them that? ^an account 

 for the figures. The two most northernly wards are mainly inhabited 

 at a distance of about two miles from the river, and their water supply 

 is mainly from tanks, and although their ground water level is slightly 

 lower than that of Ward III, yet their spleen rates are 22' 7 and 27 "9. 

 The water supply of Wards I and III is mainly from the Hooghly. 

 Still more striking are the figures for Garulia, in the northern portion 

 of which is a mill wliich has been supplying filtered water for two 

 years only, during which time the number of cases of fever treated at 

 the local dispensary has fallen to about one-third of what it was before 

 the filtered water came into use, and the greatest improvement took 

 place in the very year that every other dispensary in this area show a 

 great increase of fever. As, moreover, the native inhabitants were 

 very positive that those who drunk the filtered water suffered much less 

 from fever than those who did not, I decided to examine 100 people 

 near the mill, about 80 per cent, of whom had drunk filtered water, and 

 another series at a short distance away, but within one mile of the 

 former, and living under identical conditions, but who differed from the 

 former in not having been accustomed to drink filtered water. The 

 spleen rate was found to be 21'1 per cent, in the former, and 55 5, or 



