8 M. J. Plateau on Jets of Liquid under the 
No. 11. The modifications experienced by the jet under the in- 
fluence of vibrations are still greater, and aequire a perfect regu- 
larity when the sonorous instrument (No. 7), instead of being 
held at a certain distance from the apparatus, is put in contact 
with the sides of the vessel, and when its note is very intense 
and exactly in unison with that of the jet. The continuous part 
is then so much shortened, that the upper extremity of the first 
ventral segment almost touches the orifice; and, on the other 
hand, the superposition of the ventral segments formed by the 
individual masses (No. 4) is so exact, that no appearance of 
waves is any longer distinguishable. 
No. 12. This extreme regularity permits us to distinguish 
clearly the apparent figure produced by the passage of the sphe- 
rules interposed between the masses. This figure, which occupies 
the axis of the jet below the extremity of the continuous part, 
also possesses ventral segments and nodes, but both are shorter 
than those due to the passage of the masses. 
No. 13. By means of an instrument placed thus in contact 
with the sides of the vessel, almost all notes are capable of pro- 
ducing effects analogous to those of a note in unison with that 
of the jet; but these effects are less considerable the greater the 
divergence between the note of the instrument and the unison 
in question. 
No. 14. Morcover, under these conditions, even when the 
note natural to the jet is not in unison with that of the instru- 
ment, it may be brought into unison even if the difference between 
the number of vibrations were large enough to constitute an m- 
terval of a fifth above, or more than an octave below the note of 
the jet. 
No. 15. If the jet, instead of descending vertically, issues 
horizontally, then under ordinary circumstances,—that 1s to say, 
when it is not exposed to the influence of a sonorous instrument, 
but is allowed to strike the liquid in the vessel which receives it, 
— its discontinuous part presents ventral segments and nodes 
like those observed, under the same circumstances, in jets de- 
scending vertically (No. 6), and the vibrations of an instrument 
also modify it in the same manner. 
If the jet is made to ascend obliquely, the same phenomena 
are still observable as long as the angle formed with the horizon 
does not exceed from 20° to 25°. 
No. 16. Beyond this limit, however, and up to 45° or 50°, 
the discontinuous part assumes other aspects. When the jet is 
not under the influence of a sonorous instrument, this disconti- 
nuous part appears scattered into a kind of sheaf in one and the 
same vertical plane. Under the influence of vibrations of a de- 
terminate period, it may happen that this sheaf resolves itself 
