influence of Vibratory Motions. 7 
greater the stronger the charge, and the greater the diameter of 
the orifice. The diameter of the nodes varies in the same manner. 
No. 6. All these phenomena manifest themselves even under 
ordinary circumstances, when no vibrations are intentionally 
excited in the liquid of the vessel. The reason of this is, that, 
on the one hand, the shock of the discontinuous part of the jet 
against the liquid into which it falls gives rise to vibrations which 
are transmitted to the vessel by means of the air and the sup- 
ports; and, on the other hand, the vessel also receives through 
its supports the small vibrations due to external noises which are 
propagated by the ground. It is only when, by suitable pre- 
cautions, the vessel is protected from these two influences, that 
the jet assumes its natural aspect. 
No. 7. All the phenomena enumerated in the first five of the 
above numbers, however, become much more deyeloped and 
regular when a note, in unison with that which would be pro- 
duced by the shock of the discontinuous part of the jet against 
a stretched membrane, is produced by the aid of some instru- 
ment in the neighbourhood of the apparatus. The continuous 
part then becomes considerably shortened ; the diameter of the 
limpid portion increases still more ; the ventral segments become 
enlarged, gathering themselves more together, so that the nodes 
which separate them become more elongated ; lastly, the dia- 
meter of these nodes appears diminished. 
No. 8. Other tones, not in unison, as before, though likewise 
produced by an instrument in the neighbourhood of the vessel, 
act upon the jet in an analogous manner, but with much less 
energy. 
Lastly, there are tones which produce no effect. 
No. 9. In the particular case where the note of the instrument 
is almost in unison, the continuous part of the jet is alternately 
lengthened and shortened, and the beats which coincide with 
these variations in length can be recognized by the ear. 
No. 10. When the discontinuous part of the jet is received 
upon a body which can only vender a determinate note, it often 
happens that the vibrations of this body modify the note peculiar 
to the jet. This does not appear possible, however, unless the 
difference in pitch between the latter note and that of the body 
which receives the shock does not exceed a minor third. 
When the note of the jet is thus modified by a foreign one, a 
slight shock imparted to the apparatus, or a change in the posi- 
tion of the body impinged upon, often suffices to cause the jet 
to return to its own note, and this return is always effected 
suddenly. 
When the difference between the two notes is very small, they 
may both be heard periodically or even simultaneously, 
