540 



SUBMARINE CABLE LAYING AND REPAIRING. 



may be prepared giving the various equivalents by inspection, 

 but to be of any use currents up to 28 or 30 milliamperes must 

 be included, each in 10 subdivisions. Instead of a long table of 

 this kind, curves may be constructed from which these equiva- 

 lents can be read off. Permanent curves answering this pur- 

 pose are provided on a sheet with the calculator board, and by 

 the use of the cursors or a large pair of dividers the exact 

 equivalents for any current can be taken off very conveniently. 



0-48 



0-14 



36 



0-28 

 ^0-24 



0-20 

 0-16 

 0-12 

 O-08 

 0*04 

 



680 700 



Fig. 306. — Break Test plotted according to Schaefer's Law. 



500 520 540 560 530 600 620 6J0 

 Resistance Observed. 



Localisation curves taken in this way are shown in Figs. 

 307, 308 and 309. The series in Fig. 307 are from experimental 

 tests taken on a short end of the Commercial Company's Havre- 

 Waterville core (701b. copper 75 G.P.). The readings were 

 taken to true zero for various amounts of exposure of the end 

 from 2 in. down to a flush cut. A resistance of 1,300 ohms 



