288 M. T. Plateau on the recent Theories of the Constitution of 



liquid; which tension, at a sufficient distance from the orilicc, 

 becomes strong enough to overcome the cohesion between two 

 adjoining sections of the jet. 



Lastly, Maus adopts, with Dejean, the hypothesis of pulsations, 

 the production of which he, on his part, explains by considera- 

 tions of his own ; but convinced that pulsations alone could not 

 determine the formation of the isolated masses, he assigns the 

 discontinuity of the jet to the same cause as Magnus. 



The above theories are based, therefore, upon two hypotheses, — 

 that of pulsations at the orifice, and that of rupture caused by 

 the acceleration in the descent of the liquid. I will now endea- 

 vour to show that both these hypotheses are inadmissible. 



Before doing so, however, 1 hope to be allowed to express my 

 deep veneration for the memory of Savart. In my researches oa 

 jets I have continually had recourse to the beautiful researches 

 of that illustrious physicist ; and although I here combat the, 

 hypothesis of pulsations, I still can recognize in the same a trait 

 of genius. In fact, although pulsations do not exist in a jet 

 protected from every external influence, the case is difi'erent when 

 vibrations are transmitted to the liquid from an external source. 

 The pulsations then become a reality, they exercise upon the jet 

 the pressures and tractions attributed to them by Savart, and it^ 

 is by considering these pressures and tractions that I have beeri^ 

 enabled to explain, in my recently published Third Series, all th^^ 

 phsenomena which depend upon the influence of vibratory motions-^ 



Proceeding to our examination of the two hypotheses in ques^'^ 

 tion, let us commence with that of the rupture of the jet. The 

 idea of an effect of this kind produced by acceleration of velocity 

 is anterior to the research of Magnus. Hagcn, who made many 

 experiments on jets issuing from circular orifices, speaks of th;^^ 

 same in a memoir presented to the Academy of Berlin in 1 849, 

 " On the Discs formed by the meeting of two Jets of Liquid, and 

 on the resolution of isolated Jets into Drops*,'' but he mentions 

 the idea only in order to refute it. After some a priori con- 

 siderations relative to the probable existence of another cause, he 

 thus expresses himself: — 



"This probability becomes a certainty when we reflect that* 

 one and the same jet, whether it issues vertically upwards 6^. 

 downwards, resolves itself into drops at almost the same distance! 

 from the orifice. In the first case the velocity of the liquid may- 

 be almost destroyed by gravity, whilst in the second it may be' 

 doubled; and still the phsenomenon is not essentially different '^ 

 in the two. The fact is still more striking in horizontal jets, ' 

 where the effect of gravity almost vanishes. In these the velo- * 

 city varies only with the increase of inclination; with strong' 



vyl) >j' »i<^*# Poggendorff's Annalen, vol. Ixxviii. p. 451. 



