MEASUREMENTS AT TELEPHONIC FREQUENCIES. 131 



3. The circular graphs of current, admittance, voltage and im- 

 pedance are analyzed for the case of a divided circuit, operated at 

 constant e.m.f. and frequency. The problem of composition and 

 resolution of component and main circular graphs is discussed in 

 the light of the experimental results. 



4. The distribution of potential over a sectional high-resistance 

 box is explored, at an impressed frequency of 2,010 cycles per 

 second. 



5. The circular graph of receiving-end current is given for the 

 case of an artificial telephone cable operated at constant voltage, 

 and at the frequency of 1,208 cycles per second, when the receiver 

 has variable purely reactive impedance. 



6. Certain general propositions are offered concerning the devel- 

 opment of vector circular loci in the voltage, current, impedance and 

 admittance of an alternating current network in any steady state. 

 These propositions are shown to be connected with the equivalent T 

 or n of the network, with respect to any two pairs of selected 

 terminals. 



Bibliography. 



Without Pretensions as to Completeness. 



1. Kirchhoff. Pogg. Ann., Vol. 72, 1847. Ges. Werke. 



2. Mobius. Ges. Werke, Vol. 2, 1855. p. 245. 



3. J. Clerk Maxwell. Electricity and Magnetism, 2d ed., 1881. Vol. i, p. 



373. 



4. A. Gray. Absolute Measurements in Electricity and Magnetism, 1888, 



Vol. I, p. 160. 



5. Bedell & Crehore. Alternating Currents, 1893. 



6. Houston & Kennelly. Electrical World, Oct. 30, 1897. 



6a. A. E. Kennelly. The Equivalence of Triangles and Three-Pointed Stars 

 in Conducting Networks. Elec. World and Engineer, Vol. 34, Sept. 

 16, 1899, pp. 413-414- 



7. J. L. la Cour. Leerlauf und Kurzschluss, 1904. 



7a. la Cour & Bragstad. Theory and Calculation of Electric Currents, 

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8. Jeans. Electricity and Magnetism, 1908. 



9. A Larsen. Der Komplexe Kompensator, ein Apparat zur Messung von 



Wechselstromen durch Kompensation. Elek. Zeifschrift, Oct. 13, 

 1910, Vol. 31, pp. 103^1041 ; also The Electrical World, Vol. 56, 

 Nov. 3, 1910, pp. 1085-1088. 

 10. G. A. Campbell. Cisoidal Oscillations. Trans. A. I. E. E., Vol. 30, part 2, 

 p. 873, April, 1911. 



