1882.] 



On Liquid Jets. 



135 



obtained, there was always one drop for each complete vibration of 

 the fork, and a single stream, every drop breaking away under the 

 same conditions as its predecessor. After passing 180 it becomes a 

 question whether the octave of the fork's note may not produce an 

 effect as well as the prime. If this effect be sufficient the number of 

 drops is doubled, and unless the prime be very subordinate indeed, 

 there is a double stream, alternate drops taking sensibly different 

 courses. In these experiments the influence of the prime was usually 

 sufficient to determine the number of drops, even in the neighbour- 

 hood of pitch 128. Sometimes, however, the octave became pre- 

 dominant, and doubled the number of drops. It must be remembered 

 that the relative intensities with which the two vibrations reach the 

 jet depend upon many accidental circumstances. The table has 

 natural notes of its own, and even the moving of a weight upon it 

 may change the conditions very materially. When the octave is not 

 strong enough actually to double the drops, it often produces an 

 effect which is very apparent to an observer examining the trans- 

 formation through the revolving holes. On one occasion a vigorous 

 bowing of the fork which favours the octave, gave at first a double 

 stream, but this after a few seconds passed into a single one. Near 

 the point of resolution those consecutive drops which ultimately 

 coalesce as the fork dies down, are connected by a ligament. If the 

 octave is strong enough this ligament breaks, and the drops are 

 separated, otherwise the ligament draws the half-formed drops together, 

 and the stream becomes single. The transition from the one state of 

 things to the other could be watched with facility. 



In order to get rid entirely of the influence of the octave a different 

 arrangement is necessary. It was found that the desired result could 

 be arrived at by holding a 128 fork in the hand over a resonator of 

 the same pitch resting on the table. The transformation was now 

 quite similar in character to that effected by a fork of frequency 256, 

 the only differences being that the drops were bigger and twice as 

 widely spaced, and that the spherule, which results from the gathering 

 together of the ligament, was much larger. We may conclude that 

 the cause of the doubling of a jet by the sub-octave of the note natural 

 to it is to be found in the presence of the second component, from 

 which scarcely any musical notes are free. 



When two forks of pitches 128 and 256 were sounded together, the 

 single or double stream could be obtained at pleasure by varying the 

 relative intensities. Any imperfection in the tuning is rendered very 

 evident by the behaviour of the jet, which performs evolutions syn- 

 chronous with the audible beats. This observation, which does not 

 require the aid of the revolving disk, suggests that the effect depends 

 in some degree upon the relative 'phases of the two tones, as might be 

 expected d priori. In some cases the influence of the sub-octave is 



