Austria 



45 



of i mm. copper, insulated with gutta-percha covered with cotton. 

 They are spiralled together, and macie up into cables, containing 

 5, 10, 15, and 20 pairs, by being wound with waterproofed, and 

 then with tarred, tape. The cables are laid in larch troughs which 

 are filled in with a mixture of asphalt and hydraulic lime, and 



FIG. 



then closed with strips of wood. The asphalt mixture never 

 completely hardens, and forms no fissures through which moisture 

 can reach the cables. The success of this method is reported to 

 be complete, the cables suffering no appreciable deterioration after 

 several years' service. There has certainly been plenty of oppor- 



