322 



HENRY A. KOWLAXD 



until there is no deflection, in which case <f> = 90 or cos<= 0, therefore 



(R"R t - RRJ [#' (R" + RJ + r (R' + R"}-] + VILfl' (R' + R"} = , 



R" (R + R") 



.'. R'R. = R'R.. - VIL. 



I J? f ( J?" i J? \ i /. / V i ZP"\ ' 

 K \t T -tv.) -\- T (^JV + JK ) 



If in connection with L' a capacity C is added, the formula becomes, 

 substituting for L /t L t j~- . 



(R'R' + .R") 



c J R' (R" + ) - r (R + R"} ' 

 In most cases since I and L, are generally the self-inductances of the 



instruments the term & 2 1 L t can be neglected in comparison with - 



C 



and the equation becomes 



Tftt T> T>t -p , I R" (R 1 + R ) 



* - * + ~ 



FIG. 5. 



In this equation R, includes both the ohmic and the absorption resist- 

 ance. The value of R, is determined in terms of known quantities, 

 that is the resistance and 2 and C. It was not necessary that I and C 

 should be exactly known as the last term in the equation above plays 

 the part of a correction term, and is in all cases below small and in 

 some cases negligible. The capacities that were used in the experi- 

 ments were the 2 and 3 microfarads, the ^ microfarad Elliott condenser, 

 and the microfarad Troy condenser. 



Experiments. The process of experimenting was to apply a periodic 

 electromotive force to a and d, and to adjust the different resistances 

 until there was no deflection of the coil in the same way as in the 

 ordinary measurement of resistance on a Wheatstone bridge. The 

 different resistances R', R", R n and r being known, the apparent value 

 of the resistance R, was found, and knowing the ohmic resistance of 

 the R, circuit, the absorption resistance appears as the difference. 



