1882.] 



On Liquid Jets. 



137 



various components. Thus, the stream might be single (though this 

 is unlikely), double, triple, four-fold, or even five-fold, with a corre- 

 sponding number of drops. 



Observations were next made on the effects of chords. For the 

 chord of the fifth the pitches taken were 256 and fx 256. The two 

 forks could be screwed to the table and bowed, or, as is preferable 

 (especially in the case of the chords of the fourth and third to be 

 spoken of presently), maintained in vibration electromagnetically by 

 a periodic current from a break-fork of pitch 85^-, standing on another 

 table. The revolving disk was driven at such a speed as to give 

 about eighty-five views per second. As was to be expected, the num- 

 ber of drops was either 256 in a triple stream, or |x 256 in a double 

 stream, according to the relative intensities of the two vibrations. 

 With the maintained forks the phenomenon is perfectly under control, 

 and there is no difficulty in observing the transition from the one state 

 of things to the other. 



In like manner with forks 256 and f X256, driven by fork 64, and 

 with sixty-four views per second, the stream is either triple or quad- 

 ruple ; and with forks 256 and f x 256, we get at pleasure a four-fold 

 or five-fold stream. To obtain a good result the intervals must be 

 pretty accurately tuned. In the case of electrically maintained forks, 

 the relative phase remains unchanged for any length of time, and the 

 spectacle seen through the revolving holes is one of great beauty. 



The actual results obtained experimentally by Plateau differ in some 

 respects from mine, doubtless in virtue of the more composite character 

 of the notes of the violoncello employed by him, but they are quite 

 consistent with the views above expressed. The only point as to which 

 I feel any difficulty relates to the single stream, which occasionally 

 resulted from the action of the twelfth below the principal note. It 

 seems improbable that this could have been a single stream of the 

 kind that I obtained with some difficulty from a pure tone ; indeed 

 the latter would have been pronounced to be a double stream by an 

 observer unprovided with an apparatus for intermittent views. I 

 should rather suppose that the number of drops really corresponded 

 to an overtone, and that from some accidental cause the divergence of 

 what would generally be separate streams failed to be sensible. 



The Length of the Continuous Part. 



When a jet falls vertically downwards, the circumstances upon 

 which its stability or instability depend are continually changing, 

 more especially when the initial velocity is very small. The kind of 

 disturbance to which the jet is most sensitive as it leaves the nozzle 

 is one which impresses upon it undulations of length equal to about 

 four and a-half times the initial diameter. But as the jet falls its 

 velocity increases (and consequently the undulations are lengthened), 



