MEASUREMENTS AT TELEPHONIC FREQUENCIES. 119 



inductance L, of negligible resistance, was used as a receiving-end 

 load. The received current was measured by observing the p.d. 

 across the last resistance section pp' of the artificial line. 



With the inductance L reduced to zero, the receiving-end cur- 

 rent was observed to be the vector 01? =1.03 X lO"^ ^ 2)7° ^^' 

 liampere. The formula for I ^ is 



/« = 



i.o Z 0° 



£0 sinh d -\-jLcx} cosh d 



amperes Z (17) 



where ^o is the surge impedance of 439 \ 43°-6 ohms, 



is the angle subtended by the line 2.0 Z 44° -3 hyps Z , 

 w is the impressed angular velocity ^ 27r X 1208 = 7590 ra- 

 dians/sec. 

 With L^o, I^ becomes 1.035 X lO"^ 'x 37°. 4 ampere. 



By giving to /Loj successively increasing values up to J2640 ohms, 

 the observed received current strength was found to pursue the cir- 

 cular locus DPO. This circle has its diameter at OP, when the 

 value of the reactance is 352 ohms. At this condition, the received 

 current strength was a maximum at 1.4 X lO"^ Y 80° ampere. 



The sector of the circle in Fig. 12 between and D might have 



Fig. 13. Rectilinear graph of receiving-end impedance for case pre- 

 sented in Fig. 12, as the load of receiving-end inductance is varied, without 

 changing the resistance from zero vahie. 



