or 



Imp. gall, 



12.13 



8.41 



21.00 



16.80 



30.00 



21.00 



36.20 



25.34 



88.50 



61.95 



21.25 



14.88 



30.70 



21.49 



151.90 



106.33 



12.59 



8.81 



8.13 



5.69 



1866.] Mftih the wpply of water to Cakutta. 207 



Table I. 



For 100,000 grs. For 70,000 grs. 



1865 

 August 31st, 1865, including very fine clay,* Ebb, 

 December 6th, Ebb, 



1866 

 February 25th, Ebb, 



May 2nd, spring tide, Ebb, 



Flood : 

 24th, Neap tide, Ebb, 



June 14th, spring tide, Ebb, 



Flood, 

 July 6th, including very fine clay,* Ebb, 



August 8th, clay and some silica deducted, Ebb, 



These numbers confirm the results exhibited by Dr. Macnamara's 

 report, making allowance for difference of seasons. They shew clearly 

 the increase of solid contents more especially during the dry season. 

 And here I may remark that samples were chielly taken during 

 ebb tide, as my primary object was the examination of the river water 

 proper, and it was only during the hot season that particular attention 

 was paid to the state of tide, after my attention had been directed in 

 part to what is the special object of this paper. And indeed, except 

 during the hot season, the composition of the water is little affected by 

 the tides. 



And further, as the object was to make a full analysis of the water 

 at several different seasons, I did not adopt the readiest or simplest 

 methods of merely comparing the water at different periods for sanitary 

 purposes, which would have been done, had that been my primary 

 object. The methods adopted will be noticed in clue course. 



The preceding table exhibits a very great variation in the amount 

 of solid constituents during the hot season, owing to the influence of 

 the tides, a subject which will be separately considered. 



* These waters had settled well — that of August 1865 for 19 days, that of 

 July 1866 for about 35 days, yet by comparison with that of August 1866 

 it will be observed that about oue third of their solid contents was fine clay. 



26 



