294 



Professor Jagadis Chunder Bose 



[Jan. 29, 



Fig. 1.— Mechanical Wave Apparatus. 

 (The current regulating the speed of rota- 

 tion is varied by an interposed rheostat. 

 The counter is at the top.) 



a somewhat similar way. If 

 two metallic^ spheres be 

 strongly charged with oppo- 

 site electrifications, the me- 

 dium is electrically strained, 

 and when this strain is sud- 

 denly removed by a discharge, 

 waves are produced in the 

 medium. The discharge is 

 oscillatory, consisting of back- 

 ward and forward rushes of 

 electricity ; positive electricity 

 flowing now in one direction, 

 and immediately afterwards in 

 an opposite direction. These 

 rapid alternate flows, giving 

 rise to ether vibration, may be 

 illustrated by a modification 

 of the well-known Cartesian 

 diver experiment. By means 

 of a bulb and connecting tube, 

 alternate compression and 

 rarefaction may be produced 

 in the cylinder, attended with 

 alternate rushes of air-currents 

 through the connecting tube. 

 These give rise to oscillation 

 of the immersed ball. 



By oscillatory electric dis- 

 charge, waves are produced in 

 the ether. To produce oscil- 

 latory discharge. Hertz used 

 plates or rods with sparking 

 balls at the ends. He found 

 that the sparks ceased to be 

 oscillatory as soon as the sur- 

 face of the sparking balls got 

 roughened ; there was then a 

 leak of electricity, and no 

 sudden discharge. The balls 

 had to be taken out every now 

 and then for repolishing, and 

 the process was tedious in the 

 extreme. Prof. Lodge made 

 the important discovery that if 

 two side balls were made to 

 spark into an interposed third 

 ball, the oscillatory nature of 

 the discharge was not affected 



