36 Prof. Barton and Miss Browning on Coupled 



regulated intervals; and at longer intervals she cries, to alP 

 whom it may concern, her course and speed. All possible 

 courses and speeds might be dictated from two phonographs. 

 Timed with these wireless announcements she sends out sub- 

 marine signals also which enable ships 10 or 20 miles away to 

 estimate her distance. She is as it were surrounded by an 

 aureole of radiations transmitted both in matter and aether,, 

 proclaiming to such other vessels as enter that aureole what 

 she is ; how far off she is ; where she is going to ; and at 

 what speed she is approaching or receding. 



This is no fancy picture — It could be made reality to-day.. 

 And doubtless the time will come when it will be made 

 reality. The fabled wonders of Jason's Argo fade to common- 

 place compared with the accomplished wonders of our day. 

 The miraculous gifts of Lynceus were not so marvellous as- 

 those powers of vision and audition which Science confers 

 upon the sailor. 



II. Variably- Coupled Vibrations : III. Both Masses arid 

 Periods Unequal. By Edwin H. Barton, JD.Sc, F.P.S.,. 

 Professor of Physics, and H. Mary Browning, B.Sc.,. 

 Lecturer and Demonstrator in Physics, University College^, 

 Nottingham *. 



[Plates II.-Y.] 



Contents. 



Pa ire 



I. Introduction 86 



II. Theory of General Case for Double-Cord Pendulum. . 88 

 Equations of Motion and Coupling, 

 Solution and Frequencies. 

 Initial Conditions. 



III. Experimental Results 41 



Masses. Lengths. 



20:1. 4:.°>. 



20 : 1. 9:8. 



20 : 1. 3:4. 



Quenched Spark. 



IV. Portable Apparatus 46 



Y. Coupling Graph for Cord and Lath Pendulum 46 



VI. Possible Further Work 47 



I. Introduction. . 



IN the work described in previous papers f, the double- 

 cord pendulum was experimented with : (1) when the 

 masses of the bobs and the periods of vibration of the 



* Communicated by the Authors. 



| Phil. Mag. [6] vol. xxxiv. no. 202, pp. 245-270 (Oct. 1917) ; Phil.. 

 Mag. [6] vol. xxxv. no. 205, pp. 62-79 (Jan. 1918). 



