THE RIVER IRWELL AND ITS TRIBUTARIES. 249 



a stream to flow through a town like Manchester in its 

 present condition. The table mentioned above shows 

 that on comparing the Irwell at the Salford boundary 

 with the Medlock (jnst before it joins the Irwell), that 

 the Medlock contains 89 per cent, more albuminoid 

 ammonia^ 49 per cent, more free ammonia, 75 per cent, 

 more oxydizable organic matter, and 86 per cent, more 

 filth in suspension (flocculent matter), in short, it contains 

 about 80 per cent, or so more sewage pollution than the 

 Irwell at the Salford boundary. The Irk is very little 

 better than the Medlock. On going up the river towards 

 Bury it will be seen that the principal tributary of the 

 Irwell is the river Roach. This river rises at a height of 

 about 1500 feet above ordnance datum and on arriving at 

 the place of junction with the Irwell it has only a height 

 of 197 feet above the ordnance datum, consequently the 

 Roach is a river which can easily purify itself, if it has a 

 proper chance given to it, owing to the rapid flow of the 

 water. The Roach is a purer stream than the Irwell, 

 although it is largely polluted with sewage and other 

 contamination still, and could and ought to be far cleaner 

 than it is. The streams flowing through Elton and Bury 

 are highly polluted with dye- water, bleaching refuse, 

 sewage, &c. ; they flow through sewers into the Irwell, 

 but the Bury Corporation intends to treat all its sewage 

 outside the town, and divert it from the river in its crude 

 condition; and they will also doubtless insist upon all 

 manufacturers purifying their waste waters to such a state 

 of purity as to comply with the requirements of the Rivers 

 Pollution Act. It will be seen that there is much reason 

 for this action on the part of the Bury Corporation, for 

 on consulting Table " J)," and comparing the analysis 

 there of the Tottington Brook before it joins the Irwell, 

 with the analysis of the Irwell (taken on the same occasion, 



