THE LOCALISATION OF BREAKS AND FAULTS. 467 



Station A's Test. No milammeter. 



25 cells B= 1,140 1,138 1,138 



10 „ A= 1,239 1,240 1,245 



A-B= 99 102 107 



P= 1-977 1-977 1-977 



(A-B)P= 195-7 201-6 211-5 



A-(A-B)P = l,043-3 1,038-4 1,033-5 



Mean = 1,038 ohms = T. 

 Current ratio n= 2-5 (approx.). P by Table K. = 1'977. 



Station B's Test. 



14-5 



Mean =553 ohms = Ti. 

 Current ratio ?z = 2-43. P by Table 11 = 2021. 



Note. — During these tests the earth current was negligible, 

 and therefore there was no correction to apply. 



1,422 + 1,038-553 ^^^ , , . 

 o: — ^ =953 ohms from A. 



That is 1,422 - 953 = 469 ohms from B. 



Improved Methods of taking the Blavier. — This is a test 

 from one end of the cable only, and, as is well known, consists 

 in taking bridge measurements when the distant end is freed and 

 earthed successively. The improvement consists in keeping the 

 current the same through the fault in both the free and earth 

 readings, and is due to Mr. H. Kingsford {Journal of the Society 

 of Telegraph Engineers and Electricians, Vol. XIV., p. 534), who 

 showed that the unreliability of this test as usually taken was 

 due to the change in the resistance of the fault by the different 

 cmrents used, With a given battery power it is obvious that 



hh2 



