Belas — Water-jets, and the Effect of Sound thereon. 365 



by means of manometric capsules, and if possible to photograph 

 the effects observed in a rotating mirror. 



In conclusion, I tender my best thanks to Professor Barrett 

 for communicating this Paper, and for much kind advice and 

 assistance in the preparation of it. 



EXPLANATION OP PLATE XXXIV. 



Fig. i. 



Instantaneous photograph of a jet of water falling on a stretched 

 membrane, and influenced by a tuning-fork making 384 vibrations 

 per second. The spaces between successive large drops are equal to 

 2 cms. 



Fig. ii. 



The same jet influenced by a tuning-fork making 512 vibrations 

 per second. The spaces between the corresponding drops are equal to 

 1*5 cms. These numbers are in the ratio 4 : 3, inversely as the periods 

 of the tuning-forks. 



Figs. iii. and iv. 



The same jet influenced by both tuning-forks simultaneously, and 

 emitting a difference-tone of 128 vibrations per second. The drops 

 should then be separated by a distance of 6 cms., and this is the case 

 when the two intermediate groups of 3 drops each are eliminated, 

 as in fig. iv. These groups are formed by the breaking up of the 

 long bar of liquid after it has separated from the main column. 



NOTE. 



As the photographs for this plate have been reduced from the 

 original negative, the distances between the drops in it are not those 

 cited in the text, but are, however, strictly in proportion. The 

 distances referred to in the text are those measured on the negative, 

 and are themselves proportional to the actual distances between the drops. 



