THE DON 131 



right bank, and is an affair of three pools. The pass is 15 feet 

 wide, and the pools are practically square, and 3 feet deep. 

 The sides are strengthened by angle steel in the concrete, and 

 the lower end of each pool with steel piles. 



By decision of the Courts, the pass has to be kept running 

 full at all times, and subject only to that condition can Messrs. 

 Pirie draw off 11,000 cubic feet of water in their lade. An 

 important feature also is that this fixed abstraction of water 

 is drawn off through an orifice of fixed dimensions, and no 

 more than the above quantity can be drawn off till 6J inches 

 of water are passing over the crest of the weir. Then, by an 

 automatic adaptation of a spill weir into the lade water is 

 taken in during any subsequent rise in level. Before the 

 decision referred to, and before the Court of Session had 

 arranged for the proper amount of compensation water to the 

 river, it was usual all through summer for the whole river Don 

 to pass through the works of Messrs. Pirie. I have walked up 

 the dry bed of the river, and wondered if Scottish salmon would 

 ever learn to do the same. 



A large sewer has now been constructed along the north bank 

 of the river from Grandholm Bridge, about 3 miles from 

 the sea, and at the northern extremity of the Aberdeen city 

 boundary. This sewer discharges directly into the sea, and 

 carries off the large amount of domestic sewage and refuse from 

 works of the lower river, but it does not do anything for the 

 gross pollutions from works above Grandholm Bridge. 



Above Stoneywood the river is unmolested as regards any 

 serious obstruction, while no very apparent pollution occurs 

 for over 20 miles, past Parkhill, and Pitmedden, Fintry Water, 

 and Keith Hall. 



Below the town of Inverurie a quite unusual arrangement of 

 lades is resorted to in order to supply the North of Scotland 

 Milling Company's works, and the Port Elphinstone Paper 

 Works, with water. No dam dyke of any kind occurs to draw 

 off water. Below Inverurie Bridge the river takes a wide 

 bend, and the lade cuts off this bend. The intake or intakes 

 for at first there are two lades are simply built into the river 

 bank immediately below the bridge. Both intakes are pro- 

 tected by a substantial pile railing a few yards out in the river 

 and parallel with the bank. The distance to the lower of the 



