Sivitzerland 405 



the instrument the wire has a skin of india-rubber covered with 

 braided paraffined cotton. The earth-wire is covered with 

 paraffined cotton only. In connection with the lightning- guard 

 there is a fusible wire calculated to go at one ampere ; this is 

 to protect against the consequences of possible .contact with an 

 -electric light or power system. 



OUTSIDE WORK (LOCAL) 



In Zurich there is much to remark, for the double problem of 

 metallic circuits and underground wires has been boldy and ably 

 tackled. The desire to keep to one central station led to a great 

 convergence of overhead wires at one spot, and it became more 

 and more difficult to find room on the houses for the rapidly 

 augmenting number. Besides this, electric lighting on the high- 

 tension alternating system is rife in Zurich, and with an overhead 

 electric tramway, a duplicate of that at Leeds, tended to make 

 things more lively than agreeable for the single-wire earth-return 

 subscribers. The disturbance from the tramway was greatly 

 reduced by laying a 7 mm. copper wire between the rails to help 

 the return, and by removing (at the cost of the tramway company) 

 all wires running parallel to the tramway route. But extensions 

 of the latter are promised, and parallelism cannot be avoided 

 indefinitely ; so it was determined to place all telephone wires in 

 the centre of the town underground in cables containing twisted 

 pairs, and to distribute overhead to the subscribers from suitably 

 placed towers or columns made as sightly as possible. A con- 

 siderable portion of this work has already been completed with 

 most satisfactory results. The town council objecting to cement 

 conduits, cast-iron pipes of thirty, forty, fifty, and sixty centimeters 

 diameter are used to contain the cables, the joints being made 

 tight with lead caulking. The pipes are laid at depths varying 

 from -8 to 1-5 meters, sometimes under the street and some- 

 times under the footpaths ; they are kept straight and horizontal, 

 manholes being provided at each change of direction or of 

 level. On the straight, manholes are placed every 100 meters. 

 These manholes are of concrete, are generally one and a 

 half meters square and two meters deep, arched at the 



