216 Telephone Systems of the Continent of Europe 



tion, 250 megohms. Mr. Clouth has recently supplied several 

 cables of this nature for use under the streets of Cologne, which 

 are stated to show a capacity of only '075 mf. per kilometer, 

 although the wires are wrapped in tin-foil. The foil is the thinnest 

 procurable. The results are said to be excellent. There is no 

 overhearing between wire and wire, and a distance of sixty kilo- 

 meters is said to have been spoken over. This cable contains 

 fifty-six conductors of a resistance of 21-5 ohms per kilometer. 

 Messrs. Felten & Guilleaume's cable of this type has generally four 

 uninsulated wires strung through it (fig. 76) for the purpose of 

 connecting the tin-foil to earth. This latter firm has also sup- 

 plied the German Government with cable of the kind illustrated in 



FIG. 76 FIG. 77 



fig- 77> which is a compromise between the anti-induction single 

 wire and metallic circuit classes. Each insulated conductor is- 

 wrapped in tin-foil, and four such conductors are twisted round an 

 uninsulated copper wire, which is earthed when the cable is used 

 for single wires. When metallic circuits are required the opposite 

 wires of the same group are looped. Cables for the German 

 Government are generally sheathed in flat iron wires or some 

 other form of armouring. 



OUTSIDE WORK (TRUNK) 



There is little calling for remark about the trunk line work. 

 The wire used is generally 3 mm. copper, but for the long lines, 

 like the Berlin-Cologne, Berlin-Munich, Berlin-Vienna, and 



