American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation (1909)
Maver, William, jr. [from old catalog] · New York, Maver publishing company · leaf 176
VARLEY LOOP TEST. VARLEY LOOP TEST. 141 When these connections have been made the keys are depressed and resistanceis inserted in R until a balance is secured. When this balance has been securedit may be seen by reference to Fig. 122, that the fault is moved, as it were, to themiddle of the loop… … use of the formula, f = where f is the resistance of w, be-teen ./^ and f; l the known resistance.Or, it may be found by the formula, F = w—• ~- ; w beino- the resistance2 * of ihe defective wire; these formu-lae being the equivalent of eachother. That such is the case will beobvious on considering…
Telegraph
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