136 Mr. Waldie's Investigations connected [No. 2, 



drinking water containing as small a quantity of organic matter as 

 possible, and more particularly as small a proportion as possible of 

 that which is of recent origin. If, this being kept in mind, we take 

 up the question which seems to have been considered of greatest 

 practical importance by the Calcutta community, namely, can the 

 supply be safely taken from the river at Cossipore ? we can scarcely 

 answer it in the affirmative. My results, as has been pointed out, 

 show that there is a very distinct increase in the quantity of organic 

 matter in flood over ebb tide, even during the cold, but still more 

 during the hot season. How far this may be due to the proximity of 

 Calcutta, could only be ascertained from extended observations ; but 

 as the town must supply a considerable quantity of putrefying and 

 putrefiable matter and that of recent origin, in the absence of evidence 

 indicating the contrary, it would be desirable to avoid taking it from 

 that locality. What is the smallest distance up the river at which 

 this source of contamination is not appreciable, is a point that could be 

 determined only by observations during the hot season in various 

 circumstances and places. But it is evident enough that the further 

 up we go, the more certain are we to avoid this source of contamination. 

 But though this is an important question, it is not the only one : 

 it seems to have occupied almost exclusively the attention of that 

 portion of the community who have taken an interest in the 

 subject, while another, and in my opinion an equally important 

 one, has scarcely if at all been noticed ; and that is, what is to 

 be done with the muddy water of the rainy season ? If we look 

 to the amount of putrefying matter as indicated by the permanga- 

 nate test, or even as observed by the senses, the water, for the first 

 two months at least of the rains, is worse than the flood tide 

 water of the hot season ; if we look to the two as we have them, each 

 with its suspended mud, the rainy season water is greatly the worst. 

 If we consider the quantity of organic matter actually dissolved in the 

 water, probably the hot season water contains most, though this at 

 present is not quite certain, and it is also somewhat doubtful if it be 

 so bad in quality as in the rainy season water. Of all points in the 

 enquiry, this is the one involving the greatest doubt and difficulty, 

 and I should feel it quite impossible to give a decided opinion on it, 

 without again examining the water during that season. And what 



