* 
WITHDRAWN FROM THE ACTION OF GRAVITY. 537 
In 1851, M. Billet-Selis published, in the Annales de Chimie et de Physique, 
(t. xxxi, p. 326,) a notice on the means of observing the constitution of liquid 
veins. He there describes two different processes: the first is that which was 
indicated some time ago by myself for the observation of rapid periodical move- 
ments, the employment, namely, of a revolving disk pierced with narrow slits, 
equidistant and in the direction of the radii; the second, which is an ingenious 
- modification of that of Savart, consists in producing, by help of a large concave 
mirror, a real and inverted image of the vein, under such an arrangement that 
the vein and its image shall appear confounded. I will recall, in this connex- 
ion, another process, communicated in 1846 to the Academy of Sciences at 
Paris by M. Matteucci, (Comptes Rendus, vol. xxii, p. 260,) which is a happy ap- 
plication of that devised by M. Wheatstone, for the case of rapid movements: 
it consists in illuminating the vein by a strong electric spark. 
A memoir entitled Nouvelle Theorie del’ Ecoulement des Liquides was presented 
to the Academy of Sciences of Paris, (February 26, 1855,) by M. Dejean, but 
is generally known only by a short analysis, which we owe to the author him- 
self, and which was inserted in the scientific journals; this treats, among other 
subjects, of the constitution of liquid veins projected from circular orifices, and 
of the action exerted on them by vibratory movements. M. Dejean admits, 
for the case in which the vein is withdrawn from all extraneous action, the ex- 
istence of the pulsations which Savart supposed to be produced at the orifice 
by the efflux itself, and he seeks to explain these pulsations, the laws relating 
to their number, and a part of the phenomena which depend on the influence 
of sounds. The analysis in question makes no mention of our theory. 
Still another memoir, entitled Recherches Hydrauliques, was presented, about 
the same time, by M. Magnus, to the Academy of Berlin, (Poggendorff’s An- 
nalen, vol. xcv, p. 1.) The author occupies himself chiefly with the phenomena 
which are manifested when two veins meet under certain angles, and with the 
different aspects assumed by veins which issue from orifices of different forms ; 
but he speaks also of the constitution of veins escaping from circular orifices 
and of the influence of sounds. M. Magnus, who likewise makes no mention 
of our theory, attributes the separation of the masses which compose the dis- 
continuous part to the increasing inequality of the velocities of two contiguous 
hotizontal strata of the liquid of the vein. As to the manner in which the 
sounds act, the little that he says reverts to the idea of Savart of which we 
have ourselves made use in the present series, that, namely, of successive com- 
pressions and tractions exerted by the vibrations, but he combines it with his 
own opinion on the formation of the discontinuous part. 
Inasmuch as the theory which we have developed at the close of the second 
series is not based, as regards its fundamental principles, on hypothetical con- 
siderations, but is the necessary consequence of results of experiment; as it 
gives an explanation of all the details and of all the laws of the constitution 
of veins projected from circular orifices and not subjected to the influence of 
vibratory movements; as the present series, finally, renders equally an account 
of all the phenomena occasioned by this last influence, we have thought it use- 
less to enter into any discussion in regard to the above theories. 
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