116 



A. Pedler — On the jpast and ^present 



[No. 2, 



settling tanks, and after subsidence it is filtered through sand and then sup- 

 plied to.Calcutta. As I have made some remarks as to the quantity of the 

 former water -supply of Calcutta, this paper would not be complete if I did not 

 refer to the quantity of our present supply. From the Eeport of the 

 Municipality for the year IS79, I find that as the average for the whole year, 

 7,46-i,159 gallons of filtered water were daily supplied to the town. Accord- 

 ing to Mr. Beverley's Census of 1876, the number of inhabitants was 

 429,535, and each inhabitant would therefore receive 17'4 gallons of faltered 

 water daily. But in addition to the filtered water, there is an unfiltered 

 supply pumped up at Chandpal Ghat which is widely distributed through the 

 town, where it is I believe used for such purposes as watering the roads and 

 streets, flushing latrines and sewers, filling reserved tanks, etc. The daily 

 unfiltered supply was on the average of the whole year, 1,091,866 gallons, 

 and therefore the total daily supply in Calcutta for the past year was 

 8,556,025 gallons, equivalent to 19 92 gallons per head, or practically there 

 were 20 gallons of water available for domestic and sanitary purposes for 

 each inhabitant. This though perhaps not an abundant supply is a fairly 

 liberal one, and is very much larger than the quantity of the old supply from 

 tanks and wells. It is, however, not equal to the quantity allowed in most 

 European towns, for as pointed out in a former part of this paper the average 

 daily water supply of English towns is at least 25 gallons per head of popula- 

 tion. In this country, however, it would appear that a more liberal supply 

 would be required than in a European climate, and it has therefore been 

 proposed to double the present amount of filtered water, in which case 

 Calcutta would receive a daily supply of 16,000,000 gallons equivalent to 

 S7'2 gallons per head. If this proposal is carried out, the supply of filtered 

 water will be most abundant, and it will be amply sufl5.cient for every jjossible 

 want of the town so long as it keeps to its present dimensions. 



The quality of the hydrant water as I mentioned before has been 

 determined for four years, month by month, by Dr. Frankland's process of 

 analysis. This is certainly the most elaborate and complete method dis- 

 covered, and it is believed to show the quality of a water, not only as regards 

 its present actual constituents, but also to indicate to a certain extent, what 

 its previous history has been. In this process it may be stated the follow- 

 ing operations are j^erformed : first the amount of total solids dissolved 

 in the water is estimated, then tlie amounts of carbon and nitrogen 

 present in the organic matter are determined (tliese are called organic 

 carbon and organic nitrogen in the following tables) ; next the amount of 

 free ammonia present (if any) is determined, and the amount of nitrogen 

 contained in the form of nitrates or nitrites is estimated ; the amount of 

 chlorine present as chlorides is also determined, and finally the hardness of 

 the water, temporary, permanent and total is estimated. Of these deter- 



