THE LOCALISATION OP BKEAKS AND FAULTS. 



549 



between stations and for obtaining precise simultaneity in the 

 observations. 



Or the cables may be looped at the distant end as in a loop 

 test and current applied from one end to both, as in Fig. 313. 



Fig. 313. — Betts' Deflection Loop Method. 



Here the test is entirely under one man's control aa in a loop 

 and simultaneity is assured. 



The values for a and h are determined as previously described. 

 In this case, of course, only one battery is required. The test 

 taken in this way amounts to a loop test by the deflection 

 method. 



