450 M. J. Plateau on Jets of Liquid under the 
tions, unsymmétrically distributed inequalities of length. But, 
everything else being the same, inasmuch as the action of the 
vibrations upon the jet diminishes with their amplitude, we can 
conceive that above the octave below the principal note this action 
was probably simply insufficient ; and that if it had been possible, 
‘by a more immediate transmission, or by a better disposition of 
the system of the orifice, to augment the amplitude of the commu- 
nicated vibrations, the three notes above signalized would pro- 
bably have no longer been inactive with respect to the sheaf. 
This will be evident if we notice that the vibrations act upon jets 
issuing obliquely in the same manner as upon those descending 
vertically, and if we remember that in Savart’s experiments, 
mentioned in No. 14 of paragraph 3, and explained in the para- 
graphs 21 and 22,—which experiments were arranged so as to 
give a great intensity to the communicated vibrations—the mode 
of transformation imparted by the vibrations completely replaced 
that of the forces of figure in cases even where the notes extended 
to a fifth above the principal note. 
_ [have mentioned the possible influence of a change in the 
nature of the orifice, because that employed in my experiments 
was made in a very thin plate*, and hence this plate perhaps 
vibrated with difficulty in unison with those notes which had 
not a low pitch. 
§ 30. To complete our theoretical examination of the influ- 
ence of vibrations upon jets of liquid, we have now merely to 
show the connexion between theory and experiment with refer- 
ence to the facts of No. 17 in paragraph 3. 
Since the principal note is also that for which the period of a 
vibration is equal to that of the passage of a contraction or an 
expansion at the contracted section ($§ 5, 12, and 26), and 
since, according to experiment, the number of vibrations corre- 
sponding to this note diminishes as the direction according to 
which the jet issues deviates more from the descending vertical, 
the number of nascent contractions and expansions, and hence 
the number of nascent divisions, passing the contracted section 
in a given time must also diminish. But as the velocity of 
efflux is sensibly independent of the direction according to which 
it takes place, the number of divisions generated in a given time 
cannot diminish notably except by an augmentation in the length 
of these nascent divisions ; thus under the same charge and with 
the same orifice the nascent divisions become elongated as the 
direction of efflux deviates more from the descending vertical. 
This result may be immediately deduced from the hypothesis in 
paragraph 2; for whilst, on the one hand, a jet descending ver- 
tically tends to become thinner in consequence of the accelera- 
* Tt was only about half a millimetre in thickness. 
