444 BELL SYSTEM TECBNICAL JOURNAL 



38. H. Konig, "The Laws of Similitude of the Electromagnetic Field, and Their Appli- 



cation to Cavity Resonators," Wireless Engr., 19, p. 216-217, No. 1304 (1942). 

 "The law of similitude has strict validity only if a reduction in dimensions hy the 

 factor \/m is accompanied by an increase in the conductivity of the walls bv the 

 factor w." Original article "in Ilochf; tech u. Elek:akus, 58,' pp. 174-180 (1941). 



39. S. Ramo, "Electrical Conce[)ts at Extremely High Frequencies," Electronics, Vol. 9, 



Sept. 1942, pp. 34-41, 74-82. A non-mathematical description of the physical 

 phenomena involved in vacuum tubes, cavity resonators, transmission lines and 

 radiators. 



40. J. Kemp, "Wave Guides in Electrical Communication," Jour. I.E.E., V. 90, Pt. Ill, 



pp. 90-114 (1943).- — Contains an extensive hsting of U. S. and British patents. 



41. H. A. Wheeler, "Formulas for the Skin EiTect," Proc. I.R.E., 30, pp. 412-424 (1942)— 



Includes: a chart giving the skin depth and surface resistivit}- of several metals 

 over a wide range of frequency; simple formulas for H.F. resistance of wires, trans- 

 mission lines, coils and for shielding effect of sheet metal. 



42. R. C. Colwell and J. K. Stewart, "The Mathematical Theory of Vibrating Mem- 



branes and Plates," J.A.S.A., 3, pp. 591-595 (1932) — Chladni figures for a square 

 plate. 



43. R. C. Colwell, "Nodal Lines in A Circular Membrane" J.A.S.A., 6, p. 194 (1935)— 



Abstract. 



44. R. C. Colwell, "The Vacuum Tube Oscillator for Membranes and Plates," J.A.S.A., 



7, pp. 228-230 (1936) — Photographs of Chladni figures on circular plates. 



45. R. C. Colwell, A. W. Friend, J. K. Stewart, "The Vibrations of Symmetrical Plates 



and Membranes," J.A.S.A., 10, pp. 68-73 (1938). 



46. J. K. Stewart and R. C. Colwell, "The Calculation of Chladni Patterns," J.A.S.A., 



11, pp. 147-151 (1939). 



47. R. C. Colwell, J. K. Stewart, H. D. Arnett, "Symmetrical Sand Figures on Circular 



Plates," J.A.S.A., 12, pp. 260-265 (1940). 



48. V. O. Knudsen, "Resonance in Small Rooms," J.A.S.A., 4, pp. 20-37 (1932)— Ex- 



perimental check on the values of the eigentones. 



49. H. Cremer & L. Cremer, "The Theoretical Derivations of the Laws of Reverberation," 



J.A.S.A., 9, pp. 356-357 (1938)— Abstract of Akustische Zeits., 2, pp. 225-241, 

 296-302 (1937) — Eigentones in a rectangular chamber. 



50. H. E. Hartig and C. E. Swanson, "Transverse Acoustic Waves in Rigid Tubes," 



Pliys. Rev., 54, pp. 618-626 (1938) — Experimental verification of the presence of 

 acoustic waves in a circular duct, corresponding to the TE and TM electromag- 

 netic waves; shows an agreement between calculated and experimental values of 

 the resonant frequencies, with errors of the order of ± 1%. 



51. D. Riabouchinsky, Comptes Rendus, 207, pp. 695-698 (1938) and 269, pp. 664-666 



(1939). Also in Science Abstracts A42, j^364 (1939) and A43, 7^1236 (1940).— 

 Treats of supersonic analogy of the electromagnetic field. 



52. F. V. Hunt, "Investigation of Room Acoustics by Steady State Transmission Meas- 



urements," J.A.S.A., 10, pp. 216-227 (1939). 

 ,53. R. Bolt, "Standing Waves in Small Models," J.A.S.A., 10, p. 258 (1939). 



54. L. Brillouin, "Acoustical Wave Propagation in Pipes," J.A.S.A., 11, p. 10 (1939) — 



Analogy with TE waves. 



55. P. E. Sabine, "Architectural Acoustics: Its Past and Its Possibilities," J.A.S.A., 11 



pp, 21-28, (1939). — Pages 26-28 give an illuminating review of the theoretical work 

 in acoustics. 



56. R. H. Bolt, "Normal Modes of Vibration in Room Acoustics: Angular Distribution 



Theory," J.A.S.A., 11, pp. 74-79 (1939). — Eigentones in rectangular chamber. 



57. R. H. Bolt, "Normal Modes of Vibration in Room Acoustics: Experimental Investiga- 



tions in Non-rectangular Enclosures," J.A.S.A., 11, pp. 184-197 (1939). 



58. L. Brillouin, "Le Tuyau Acoustique comme Filtre Passe-Haut/' Rev. D'Acoiis., 8, 



pp. 1-11 (1939). — A comparison with TM waves; some historical notes, tracing the 

 inception of the theory back to 1849. 



59. E. Skudrzyk, "The Normal Modes of Viijration of Rooms with Non-Planar Walls," 



J.A.S.A., 11, pp. 364-365 (1940).— Abstract of Akustische Zeits., 4, p. 172 (1939).— 

 Considers the equivalent of the TAl 00/) mode. 



60. G. M. Roe, "Fre((uency Distribution of Normal Modes," J.A.S.A., 13, pp. 1-7 



(1941). — A verification of Maa's result for a rectangular room, and an extension 

 to the cylinder, sphere and several derived shapes, which leads to the result that the 

 number of normal modes (acoustic) below a given frequency is the same for all 

 shapes. 



