I860.] with the supply of water to Calcutta. 205 



12 grains per Imp. gallon during the months of April, May and 

 June ; and this increase in quantity and deterioration in quality is 

 considered to be due to the organic impurity from the sewers and banks 

 at Calcutta. The analyses, I may observe, were chiefly made on samples 

 taken at high water, obviously to get the water at its worst. Analyses 

 are also given of the waters of two tanks in the Maidaun or plain round 

 Fort William, namely Monohur Doss's Tank and General's Tank, 

 which are considered as unquestionably superior to the river water. 



I may observe that, when I commenced this investigation, it was not 

 in connection with the water supply of Calcutta at all, or even in con- 

 nection with the economical use of water or its wholesoinencss as a 

 beverage. These enquiries had been placed in the hands of others ; but 

 it occurred tome, that residing, as I did, on the banks of the Hooghly, 

 and possessing certain facilities for the purpose, it might be a contribu- 

 tion to science of some small value to make a minute examination of 

 the constituents of both the water and the mud of a great river 

 draining so large an extent of country as the Ganges. The investiga- 

 tion is as yet far from completion, but during its course, it occurred 

 to me that many of the results obtained might have some value in 

 relation to the subject just adverted to — the economical use of water ; 

 and that the local interest attached to it might render it in some 

 degree appropriate to publish these results, more particularly at a 

 time when all the knowledge attainable connected with the subject 

 is desirable. 



This communication then is not intended to present a full statement 

 of the composition of the Hooghly water, but only to treat of such 

 points as are of more particular interest in connection with its applica- 

 tion to supply the wants of the inhabitants of Calcutta. And indeed 

 this is all that is necessary for the purpose in view. As regards the 

 general composition of the river water at different seasons of the year, 

 my own results only go to confirm those already given in Dr. Mac- 

 namara's Report, but in some particulars, not of minor importance, the 

 results I have obtained and the conclusions drawn from them are 

 somewhat different ; and in other particulars it may be found that I 

 have added to the stock of information on the subject. 



It is scarcely necessary to allude to the course of the seasons in 

 Bengal and the way in which they affect the river. But for 



