Sounds of Splashes. 175 



a selvit cloth. Above a certain height of fall (146 cm.), it is 

 found that the records are somewhat inconsistent although 

 each time the ball is rubbed with equal care, thereby 

 showing that a very small difference in the surface will 

 influence the nature of the splash very near the critical 

 height. 



The paper is accompanied by eight photographic records of 

 the sounds of splashes obtained in the above experiment 

 (Pi. XXIII.) In all these the plate moves past the narrow 

 rectangular vertical slit of the camera with a high speed, and 

 I have used ordinary Empress plates to ensure the moving- 

 spot of light making a good impression on the photographic 

 plate. The whole apparatus is mounted in the dark-room and 

 a narrow beam of sunlight is projected into the dark-room 

 through a hole in one of the shutters of the windows by 

 means of a heliostat set in motion by clockwork. With this 

 arrangement it is found that a good negative is obtained by 

 developing the plate for about a minute in a normal solution 

 of metol-hydroquinine. 



These records clearly show that in one of a basket-splash 

 there w r as a violent disturbance at a particular stage followed 

 by another small disturbance, and that the first violent one 

 w r as considerably damped while there was very little damping 

 in the small one. A photograph of the apparatus in toto is 

 also given (fig. 9). 



The investigation is being continued with a view to study 

 the phenomenon with spheres of different substances and also 

 to ascertain how it depends on the nature of the liquid. 



As even the ordinary ear observation shows that up to a 

 certain height the splash was perfectly noiseless and the spot 

 of light was at rest, the large number of the records obtained 

 for the low heights are not given here. In all these cases 

 the curve is only a straight line, showing thereby that the 

 splash was noiseless. 



The records show that the critical height of fall of the 

 highly -polished steel sphere in the case of water is approxi- 

 mately 153 cm. 



Department of Physics, Maharajah's College, 

 Vizianagaram, Madras, India. 

 2nd April, 1921. 



