328 Mr. G. A. Campbell on Loaded 



The artificial cable, which consisted of mica condensers and 

 German-silver resistances, does not show conspicuously. 



One of the transmitting stations is shown at the left of the 

 photograph. The receiving station is shown in the second 

 photograph. At this station there were switches and an 

 artificial cable, in addition to the telephone set. The artificial 

 cable, known as the u cable standard/' consisted of mica con- 

 densers and German-silver resistances. The photograph (fig. 3) 



Fi»\ 3. 



shows the thirty boxes, each containing ten condensers, and. 

 somewhat indistinctly, the German-silver wires. Jt also 

 shows a jack strip and two cords and plugs, by means of 

 which any length of cable up to thirty miles, by steps of one 

 mile, could be put in circuit. For lengths greater than thirty 

 miles another artificial cable was added to this. 



The manner of making the test was as follows : — The cable 

 was connected back and forth without the loading coils and 

 the artificial section was also connected up without the load- 

 ing coils, and then the wliole of this circuit was compared 

 with the cable standard. It was found that the entire cable 

 and artificial section were equivalent to forty-six miles of the 

 cable standard, and shorter lengths were equivalent to cor- 

 responding lengths of the cable standard. Next, the coils 

 were introduced into the cable circuit and into the artificial 

 section, making a cable circuit forty-six miles in length with 

 four hundred equally spaced loading coils. The transmission 

 was greatly improved and found equivalent to the trans- 

 mission over twenty-three miles of cable standard, and in 



