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LXVIL Mechanical Illustration of three Magnetically 

 Coupled Oscillating Circuits. By A. L. Narayan, M.A* 



[Plate XII] 

 Synopsis* 



THE paper is a continuation of the experiments made by 

 the author on Coupled Circuits, and gives a short 

 account ot three mutually interacting pendulums which he 

 used, in order to illustrate the theory of three magnetically 

 coupled circuits. The mathematical theory of the mechanical 

 system is developed. 



The apparatus is a modified form of the one used by the 

 author in his previous paper on Coupled Circuits. The 

 paper is illustrated by ten photographic reproductions of 

 the vibrations of the three pendulums under various con- 

 ditions of starting, the method adopted for photographing 

 the vibrations being essentially the same as that adopted 

 by the author in his previous experiments, and therefore 

 entirely different from that adopted by Prof. Barton and 

 Miss Browning. The whole arrangement serves as a very 

 convenient model for demonstrating the action of three 

 electrical circuits to a large class. 



In the Philosophical Magazine for November 1920, Prof. 

 Barton and Miss Browning describe a model of triple 

 pendulum as a mechanical analogue of three mutually 

 interacting electrical circuits. In this paper an entirely 

 different kind of mechanical system, which the author 

 used in order to elucidate and interpret the theory of 

 three magnetically coupled oscillating circuits, is described, 

 and the mathematical theory of the mechanical system is 

 developed. 



The coupled system in this case is a modified form of one 

 used by the author in his experiments to study variably 

 coupled vibrations of two interacting circuits which illustrates 

 the theory of the oscillation transformer. It consists (as 

 shown in photograph fig. II., PI. XII.) of three rigid 

 pendulums, A, B, and C, of which A can turn freely 

 about a horizontal axis by means of a steel knife-edge 

 resting on a bracket. The pendulum B can be suspended 

 from A by means of a steel knife-edge resting on a 

 V-bracket, which can be screwed at different points along 



* Communicated by the Author. 



