in Melbourne. 189' 



soundings with a tin vessel attached to a pole led to the 

 conclusion that not more than 3 feet of solid matter lay at 

 the bottom, and it may be doubted whether there would 

 have been so much if the apparatus had been fitted with the 

 disintegrating contrivance which has been mentioned as 

 forming part of Dr. Tracy's filter. I should mention here 

 that portions of solid excrement were seen in the street 

 channel adjacent to and below the outlet of the filter drain. 

 These were not actually seen by me to proceed from the 

 drain, but whether they did or not is of little importance ; 

 they, might easily have done so. Such matters are not- 

 likely to be ejfficiently arrested by an arrangement which 

 allowed free passage to lumps of solid meat as large as- 

 filberts. The small amount of solid matter left behind 

 showed plainly that enormous quantities had gone through,, 

 and that in fact the filter was no filter at all ; it was a mere 

 strainer which only delayed the passage of the excremen- 

 titious matters until they were sufficiently broken up to- 

 pass through the blowholes. In a newly-laid filter, before 

 these blowholes are formed, the contents of the cesspits, 

 require to be completely comminuted before they can escape, 

 for the mass has to be reduced to the state of a liquid in 

 which the insoluble particles are so finely diffused as to 

 simulate solution; and this appeared to be the case in 

 Dr. Tracy's, which was better constructed, but even then I 

 learned that the amount left behind was very small. That- 

 this comminution does take place, even with the more 

 refractory paper and rags, is plainly shown by the abundance 

 of cotton and flax fibres and other vegetal tissues found, on 

 microscopic examination of the clear colourless water that 

 passes off. The escaping matters are frequently masked to 

 the senses of sight and smell by the immense volume of 

 water in which they are suspended. A stream of water was 

 constantly flowing, and on occasions when inspection was. 

 made by appointment the flow was much stronger. Thus, 

 then, the filtering process appears to fail of its object, even 

 if regarded solely as a mechanical agent. A larger proportion 

 of the solid matter becomes soluble as a result of fermen- 

 tation and decomposition, and the question only appears to 

 be whether it shall undergo a part of this change in the 

 primary receptacle, in the streets of the city under the noses 

 of its inhabitants, or in the river, which exhales its fogs and 

 vapours fraught with the volatile portions of the filth that, 

 is poured into it. 



