XXXVI. F. M. GUMMOW. 



The drum, after being oiled to prevent the cement adhering to 

 it, is coated with a thin cement grouting, over which is spread a 

 layer of cement-mortar. This layer is well consolidated with 

 wooden floats, and roughened to receive the next layer. 



A netting is next strained round the cement-mortar and 

 fastened off, over which is wound a spiral wire (Type A). The 

 whole surface is then grouted, and a second layer of cement- 

 mortar is put on and worked as previously described to about 

 |" from the full thickness of the completed pipe, and then a 

 second spiral wire is wound round as before. 



This surface is then grouted, and a third and final layer of 

 cement-mortar is put on, well consolidated, and the pipe finished 

 off to its required thickness. 



In the manufacture of pipes with only one spiral wire (Type 

 B), the operation is slightly different, in so far that after placing 

 the netting round the first coating the surface is grouted and the 

 second layer is put on, but in such a way as to form an eccentric 

 shape, around which the spiral wire is wound, and the third and 

 final layer is then put on, and the pipe finished off. 



Immediately upon completion the pipe, drum, and spindle are 

 lifted out of the sockets and placed in a vertical position on a 

 truck, and removed to any convenient place ; a second drum is 

 then placed in position, and the process repeated. The finished 

 pipe is left for about three days on the drum, then taken off 

 the truck, the ends of the drum removed, and the steel lining, 

 which is collapsible, extracted without difliculty. 



The inner surface of the pipe is then rubbed, and if considered 

 necessary, "bagged" over with cement and left ready for sale. 



A number of tests have been made by the Sewerage Depart- 

 ment of New South Wales demonstrating the great strength and 

 elasticity of the pipes. Even when badly fractured under a 

 heavy load during testing, they still were able to sustain the load 

 placed on them without collapsing, and after removing the load 

 they partially recovered their original shape, thus showing the 

 elastic nature of such a construction. 



