influence of Vibratory Motions. 19 
in such a jet the continuous part has different lengths which 
succeed each other periodically ; the shortest of these lengths, 
however, ought to be considered as that of the veritable conti- 
nuous part of the jet, because in it the continuity is never inter- 
rupted, and it must necessarily be shorter than it would be if the 
same jet were not submitted to the influence of a sonorous in- 
strument. 
At the same time, however, the shortening of the continuous 
part ought to be less than in the case of unison. In fact, if the 
note of the instrument has a higher pitch than that of the jet, 
the most complete coincidence between the two actions can, as 
above remarked, only establish itself about the middle parts of the 
contractions where it exists, and at the extreme portions there is 
conflict. If the note of the instrument has a lower pitch, the 
concurrence, it is true, extends throughout the whole contrac- 
tion, but then conflict exists in the adjacent portions of the two 
expansions, between which the contraction is situated; and as 
these portions admit with less facility the liquid chased thither 
by the contraction, the latter cannot freely obey the two actions 
which simultaneously tend to attenuate it. 
In the second place, the shortening, according to the above, 
ought to be less the more the note of the instrument deviates 
from being in unison with that of the jet; for the higher its 
pitch above the latter, the less the portion of the contraction 
which corresponds to the above-described coincidence; and the 
lower its pitch below the note of the jet, the further the conflict 
extends upon the adjacent expansions. 
Lastly, since upon the contractions corresponding to coinci- 
dences, and up to a certain distance above and below each of the 
same, the action of the vibrations favours more or less that of 
the forces of figure, the other modifications determined by unison 
ought also to be manifested by the jet in an analogous, though 
in a less decided manner; thus the limpid portion will again 
appear a little thickened, and the agitated part will have ventral 
segments and nodes; these modifications, however, will be again 
less developed the greater the interval between the note of the 
instrument and that natural to the jet. 
The complication of the subject permits us, therefore, merely 
to enunciate, as results, the following four conclusions :—When 
a note of a higher or lower pitch than that natural to the jet is 
produced at a certain distance from the apparatus,—l1st, the 
continuous part ought to assume different lengths periodically ; 
‘2nd, the shortest of these lengths, which is that of the veritable 
continuous part, ought to be shorter than the unchanging con- 
tinuous part was before the action of the instrument, but longer 
than it would be in the case of unison; 3rd, the jet ought to 
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