THomson.—On the Cleansing of Towns. 61 
circulated with the authority of a responsible public body, it is impossible 
to overrate the grave importance which attaches to such statements” as are 
contained therein. 
Again: The Engineer states that, **in order to simplify the subject as far 
as possible, we propose to direct our enquiry to the following points, viz.:— 
“1st. Whether there is any evidence that foul and offensive accretions 
have formed within the channel of the Thames since the metropolitan 
sewage outfalls came into operation. 
‘2nd. Whether careful analyses do show a perfect identity between the 
constituents of the Thames mud and those of the metropolitan sewage. 
* 8rd. Whether it is true that the sewage discharged at Barking and 
Crossness does work its way upwards, and cause the same pollution of the 
Thames within and about the metropolitan area as formerly existed. 
“dth. As to the quantity of solid matter contained in the sewage dis- 
charged into the Thames at Barking and Crossness, and whether it is suffi- 
cient to produce any sensible deposit in the bed of the river, and as to the 
real cause of such deposit." 
As to the recent formation of foul and offensive accretions, the Engineer 
argues that comparison of the state of the river thirty years previous to 
1861, and that in fifteen subsequent years, has “no value or significance 
whatever." Further, when it is considered that the traverse sectional areas 
of the river taken at half-tide off the Crossness outfall have been increased 
by the removal of shoals,” &e., “it would be no matter of surprise if the 
river in this part of its course should be even more liable to partial deposits 
forming upon the banks than it was formerly." 
He then enters into the subject of the Woolwich shoals, and concludes 
“that it is obviously impossible to draw the conclusion which Captain Calver 
suggests, that because mud is found in this part of the river, therefore it 
comes from the metropolitan sewers." Then as to the mud deposits higher 
up, near Waterloo Bridge, he remarks ‘that it is obvious that the deposits 
of mud above referred to, and which, it appears, accumulated in a few 
months time, could not have resulted from the sewage discharged into 
the river upon the ebb-tide at a point no less than 14j miles lower down 
the stream." 
— Next, as to the identity of Thames mud with sewage mud, the Engineer 
endeavours to show the fallacy of much of Captain Calver's arguments. 
This is illustrated by a table, from which he (the Engineer) surmises that 
‘‘it is perfectly obvious that no conclusion can be possibly true which is 
founded upon the supposed * perfect identity' of quantities which vary from 
0°85 to 40-91." 
