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analysis of the Irwell (taken on the same occasion, before 
being joined by the Tottington Brook), in table C,” it will 
be at once seen that the Irwell is a pure stream in com- 
parison. I have analysed otlier small streams flowing 
through Bury into the Irwell, and found all were largely 
polluted with manufacturer’s waste water. Between the 
junction of the Roach and the Irwell there is a pollution of 
the Irwell by the River Croal. This river is formed b}^ the 
junction of several brooks, of which the principal is the 
Bradshaw Brook, flowing near Bolton. This brook — and, 
in fact, all of them — are largely polluted with manufacturer’s 
waste waters and sewage, but all of them are much purer 
than the Irwell at the Salford boundary. From my exami- 
nations of the river, and the curves plotted from the weekly 
analyses of 1884, compared with the analyses of 1885, I 
cannot draw any other conclusion than this, that about One- 
half the total pollution of the Irwell, before it arrives at 
the weir at Throstle Nest, is due to manufacturer’s waste 
waters — in other words, to avoidable pollution. This con- 
clusion is supported by looking at the oxygen curves pro- 
duced by calculating on 100 parts of the total matters in 
solution (Curve No. 6). It will be seen that there was a 
continuous rise in the amount of oxygen required to oxydise 
the organic matter in 100 parts of the total soluble matters, 
owing, no doubt, to the long drought in 1884 (extending 
from March to J uly 4th ; see rainfall in table “ A ”) ; hut 
suddenly, on June 6th, the curve drops from about Jf7 grains 
to 22. This diminution is due to the whole week being 
a universal holiday in Lancashire, viz., Whit-week. The 
same fact is observed on examining Curve No. 6 (for the 
Christmas and New Year holidays in 1884-85) in quite as 
striking a manner. Again in the Easter holidays and Whit- 
week in 1885 the same improvement is observed, proving 
conclusively that the pollution of the river is very much 
