• 414 SUBMAEINE CABLE LAYING AND KEPAIKING-. 



Balances : — The Balance B with the high current is taken 

 first. 



37 cells, i9m/ampsB = 7,050 7,070 7,050 7,090 7,100 7,110 7,110 7,100 



16cells,^m/ampsA = 7,420 7,500 7,420 7,540 7,600 7,550 7,630 7,590 

 o 



A-B= 370 430 370 450 500 440 520 490 



P = l-977 1-977 1-977 1-995 1-995 1-995 1-995 1-955 



(A-B)P= 731 850 731 898 997 878 1,037 978 



A-(A-B) P = 6,689 6,650 6,689 6,642 6,603 6,672 6,593 6,612 



Correction (additive) = 76 76 76 100 100 100 100 100 



a; = 6,765 6,726 6,765 6,742 6,703 6,772 6,693 6,712 

 Mean of 8 pairs = 6,785 ohms. 

 Actual distance of break =6,744 ohms from Sierra Leone. 



After the third pair had been taken the reading on the 

 milammeter for the high current changed from 40 to 39*5, 

 and kept at this until the end of the test. 



The ratio of the currents and values of P were, for the first 

 three pairs — 



^ = 2-50. P (By Table) = 1-977, 

 16 



remaining pairs — 



— = 2-47. P (By Table) = 1-955. 



The earth current being 1,090 millivolts at the beginning 

 and 1,417 millivolts at the end of the test showed that a con- 

 siderable rise took place. The balances also show that a 

 change occurred after the third pair had been taken, and there- 

 fore the earth current correction before testing was applied to 

 the first three pairs, and the correction, after testing, to the 

 remaining pairs. The correction for the first three pairs is 



worked out as follows : — 



40 

 Eatio of testing currents —- = 2-50. 

 16 



By Table, M = 0-465. 



nc is the high current to line in milliamperes. 



