WITHDRAWN FROM THE ACTION CF GRAVITY. 325 
these spherules pass through oscillations of form, since the trace of their 
passage before the eye presents expansions and nodes. 
For the purpose of elucidating this point let us examine, attentively, what 
are the circumstances in regard to the spherules and in regard to the large 
masses. Let us remember (2d series, § 62) that the thread generally separates 
into three parts, of which the two extreme ones reunite themselves respectively 
with the two large masses between which the thread is comprised, while the 
intermediate one contracts itself at once and symmetrically from above and 
below, dilating at the same time horizontally so as to produce the spherule in 
question. By virtue of this simultaneousness and symmetry of action, the 
small portion of liquid attains the spherical form towards which it tends, but it 
does so with an acquired velocity and thus necessarily overpasses it, so that 
its vertical diameter becomes less and its horizontal diameter greater than the 
diameter of the sphere of the same volume; hence the oscillations of form of 
the spherules, and consequently the expansions and nodes which result from 
, them. 
Things do not occur, however, after identically the same manner with the 
large mass suspended to the thread and which is isolated by its rupture; in 
effect, a moment before this separation the mass in question was already ren- 
dered free at its lower part by the rupture of the thread formed between it 
‘and the mass which precedes it; here, then, the ruptures below and above the 
mass, and, of course, the two contractions which tend to flatten it in the verti- 
cal direction, do not take place at the same time; besides, as each of these 
contractions must be followed by an elongation, neither do these take place 
simultaneously, and the same is the case consequently with the contractions 
and elongations which follow. ‘Thus each contraction from the bottom of the 
mass will be effected wholly or in part while an elongation is taking place 
above, and vce versa; but the first tends to increase the horizontal diameter 
of the mass and the second to diminish it; their effects on this diameter will, 
therefore, more or less destroy one another, and if there be no vibratory influ- 
ence which, by the accession of velocity which it imparts to the transforma- 
tion, shall carry the diameter in question beyond that of the sphere and thus 
determine an excess of pressure to the equator of the mass, this diameter will 
vary but little, and consequently we shall observe no system of expansions 
and nodes in the discontinuous part of the vein. We see that, even under the 
sole action of the contigurative forces, the masses which become isolated at the 
extremity of the continuous part are necessarily the seat of oscillations of 
form, though these oscillations can only exist in a marked degree in the vertical 
direction. We have, therefore, committed a slight error in § 69 of the 2d 
series, by saying that, after being isolated, the masses at once form themselves 
into spheres. 
§ 19. Let us return, for an instant, to the spherules. When a thread is trans- 
formed, the small constrictions therein produced become themselves changed 
into still more slender threads, each of which breaks at two points, and thus 
furnishes, by its middle portion, an exceedingly small spherule, (2d series, § 62.) 
These last spherules are frequently thrown beyond the axis of the vein, im- 
pelled, no doubt, by the movements of the air; but as their mode of genera- 
tion is the same with that of the less minute spherules of which we took no- 
tice above, they also must undergo oscillation$ of form, and Savart assures us 
that this is the case, though without indicating by what means he verified it: 
the parabolic trajectory described by such of these spherules as are projected 
beyond the vein leaves probably on the eye.a trace sufficient to allow the ob- 
servation therein of expansions and nodes; it may be also possible, perhaps, 
to distinguish the apparent figure resulting from the passage of those which 
maintain their position in the axis. 
