WATERWORKS VI' EAST LONDON. 331 



The new waterworks are now in course of construction, and 

 I hope members will have an opportunity of inspecting them. 

 Almost the whole of the work is being carried out by direct 

 labour. 



Corrosion in Iron and Steel. 



In connnon with other waterworks undertakings we have 

 had the same unfortunate experience in regard to corrosion 

 in steel, and latterly in wrought iron mains. 



Parts of a 12-inch rising main and supply main that was 

 laid in 1905 had become so perforated in 1913 that they were 

 found unfit for further service. Some of these mains were 

 replaced with cast iron mains, and others were successfully 

 encased in a siftings concrete stringer octagon in shape. In 

 all cases the steel had a minimum covering of 2^^ inches of 

 concrete. 



This corrosion takes place from the outside and is 

 undoubtedly due to salts in the soil. Where the soil was known 

 to be brak the corrosion was most intense- We had as many 

 as 125 distinct perforations in one length of 12-inch pipe. I had 

 noticed that wrought iron also suffered from corrosion, but to 

 a very much less degree ; however, I found last year thai mains 

 laid in 1899 were unfit for further use. In this connection 

 photographs, which I exhibit, of two of the mains may be of 

 interest. So as to stop the leaks they were plugged with 

 hardwood and dusted with neat cement. In this manner they 

 were kept in service for some time. 



Corrosion in Steel Rails. 



The electrical scheme is entirely under the control of the 

 Electrical Engineer (Mr. Eambe), but I was associated with 

 Mr. R. L. Cousins during my first term as Town Engineer, when 

 the scheme was constructed. The weight of the rails laid was 

 75 lbs. per linear yard, 15 lbs. per yard heavier than any 

 in use in the country at the time. They were well and properly 

 laid on a concrete stringer. However, they suffered so much 

 from corrosion that in 191 1 the lower flange of the rail had 

 been almost entirely eaten away, and the track had become 

 unstable. Members may be interested in inspecting photographs 

 of these rails with which Mr- Lambe kindly supplied me, and. if 

 they so desire, I shall be glad to show them specimens of the 

 rails. 



Settling Tanks. 



Two new Settling Tanks of J/2 million gallons each above 

 the draw-off were completed in 1918, in the vicinity of the 

 Agricultural Show Grounds. Whenever necessary, we are now 

 able to precipitate our water anterior to filtration. We did sue- 



