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



consider that the settling of the muddy water of the rains for 36 

 hours will put the water on an equality with that of the rest of 

 the year as to the rapidity with which it will pass through the 

 filter, and, I suppose, with or without the magnetic carhide, will 

 supply it in an unobjectionahle state. At least I cannot find in the 

 Report any provision made in addition to this for the special case 

 of the muddy waters of the rains, or a single arrangement made to 

 provide against any difficulty in this case. 



My own observations on the waters of the rainy season are not at 

 all in favour of the success of this scheme. On the contrary, I have 

 experienced the greatest difficulty in getting the water freed from the 

 finely suspended matter by either subsidence or- filtration. After 

 standing to settle for several weeks, it still contained much of this 

 finely suspended clay, from which it could not be freed by filtration in 

 the ordinary way. It seems therefore to be impossible to avoid the 

 conclusion that through the ordinary sand filter the water will pass 

 little changed ; or if by any modification it be made effectual, it will 

 pass with such extreme slowness as altogether to interrupt the 

 ordinary supply of the water. And if it pass in its muddy state into 

 deep covered reservoirs provided for it, daily it will deposit a portion 

 of its mud, which will be daily more or less stirred up by the new flow 

 of water into the reservoir, a state of matters which appears to be 

 very well adapted to maintain the water in the state in which it 

 entered, or even to tend to make it worse. Whether the water of this 

 season then will be in a fit state for storage, after thirty-six hours 

 settling and the short time longer necessary for its passing though the 

 filter and being conveyed to the reservoirs, is a question deserving of 

 serious consideration. My own observations lead me greatly to doubt 

 it. It would be rather a serious error, if these fears should turn out 

 to be well founded ; for not only would the water be offensive during 

 the rainy season, but, unless the reservoirs were cleaned out, would 

 continue to be so. And in the plan there appears no arrangement 

 for cleaning them, and no facilities for doing so. 



There are other and effectual plans for speedily separating the 

 suspended mud from the water, and rendering it easy to be filtered 

 perfectly transparent. These are by chemical precipitants, to some 

 ■of which I have previously alluded ; one well known is alum, in daily 



