458 KENNELLY, TAYLOR— PROPERTIES OF 



fastened to the center of a telephone diaphragm, and tuned nearly 

 into consonance therewith, gave rise to a large reentrant loop. 



8. A provisional but apparently satisfactory theory of loop dis- 

 tortion is given in Appendix II. 



9. An experimental form of coupled multiple pendulum is de- 

 scribed, which affords a visual manifestation of the essential phe- 

 nomena of the motional-impedance circle, and of its loop distortions. 



10. Means are described for applying a correction for the ab- 

 sorption due to the use of an amplitude measurer, when determin- 

 ing the motional constants A, m, r and .r of a telephone receiver, 



BIBLIOGRAPHY. 



1. M. J. Lissajous. Memoire sur I'fitude Optique des Mouvements Vibra- 



toires. Annales de Chimie et de Physique (3), p. 147, LI., 1857. 



2. Rayleigh. Theory of Sound, Vol. I., p. 147, Macmillan Co., 1894. 



3. A. Campbell. On the Measurement of Mutual Inductances by the Aid of 



a Vibration Galvanometer. Phil. Mag., p. 494, May 14, 1907. 



4. E. H. Barton. Text-Book of Sound, p. 146. Macmillan Co., 1908. 



5. W. Duddell. Bifilar Vibration Galvanometer. Phil. Mag., pp. 168-179, 



July, 1909 ; Electrician, 63, pp. 620-622, July 30, 1909. 



6. Frank Wenner. A Theoretical and Experimental Study of the Vibration 



Galvanometer. Bull. Bur. of Stand., Vol. 6, No. 3, p. 347, Feb.. 1910. 



7. A. E. Kennelly and G. W. Pierce. The Impedance of Telephone Receivers 



as Afifected by the Motion of their Diaphragms. Proc. Am. Acad, of 

 Arts and Sciences, Vol. XLVIII., No. 6, Sept., 1912; also Electrical 

 World, N. Y., Sept. 14, 1912; also British Assoc. Adv. Sc. Report Dun- 

 dee meeting, 1912. 



8. R. L. Jones. Simple Vibratory Systems and their Impedance Analysis. 



Western Electric Co. Eng. Dept. Report, Sept. 24, 1914. 



9. A. E. Kennelly and H. O. Taylor. Explorations over the Vibrating Sur- 



faces of Telephonic Diaphragms under Simple Impressed^ Tones. 

 Proc. Am. Philos. Soc, Vol. LIV., April 22, 1915. 



10. A. E. Kennelly and H. A. Afifel. The Mechanics of Telephone-Receiver 



Diaphragms, as Derived from their Motional-Impedance Circles. Proc. 

 Am. Acad, of Arts and Sciences, Vol. LI., No. 8, Nov., 1915. 



11. H. G. Crane and C. L. Dawes. Construction of a Lecture-Room Oscillo- 



graph. Electrical World, p. 424, Vol. 67, February 19, 1916. 



List of Symbols Employed. 



A Torque constant of a vibration galvanometer or oscillograph 



(dyne-perp.-cm. per absampere). Also force constant of a 



telephone receiver (dynes per absampere). 



c = n./ni Acoustic interval between quadrantal frequencies (numeric), 



A Damping constant, a hyperbolic angular velocity (hyp. radians 



per sec). 



