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



and afterwards by employing the precautions indicated by Savart 

 for deadening these effects. In the first case, the result was sen- 

 sibly conformable to the engraved figure of which I spoke, which 

 figure no doubt corresponds to conditions of change and orifice 

 analogous to those in my experiment ; and in the second case, 

 the result, as will be seen, was not essentially different. The jet 

 issued from an orifice 3 millims. in diameter at an angle of about 

 35° with the horizon ; the amplitude of the jet, that is to say, 

 the horizontal distance from the orifice to the most exterior part 

 of the sheaf, varied, according to the diminution of the charge, 

 from 1'45 metre to 1-27 metre; and the height of the summit 

 of the jet above the level of the orifice varied from 0*34 metre to 

 0*32 metre. In the second observation, a carpet folded several 

 times until its thickness amounted to 8 centims., was interposed 

 between the vessel from which the jet issued and the massive 

 table upon which it rested, and under the feet of which cushions 

 were placed. The vessel into which the sheaf fell was placed 

 upon a truss of hay, and the sheaf glided down a thick plank 

 suitably inclined. Besides this, the orifice at the bottom was 

 furnished with a contrivance, similar to that described by Magnus, 

 for preventing any rotations in the liquid ; the limpid portion of 

 the jet was also regular, or nearly so. Notwithstanding all these 

 precautions, the effect of the small vibrations proceeding from 

 exterior noises was not completely annulled ; for the continuous 

 and limpid portion of the jet suffered intermittent shortenings, 

 and even speaking in the neighbourhood of the jet was sufficient 

 to render these shortenings more visible. It will be admitted, 

 however, that the vibrations which still remained must have been 

 very feeble ; nevertheless the sheaf manifested itself quite as well 

 as under the free influence of these vibrations, and its origin 

 never receded beyond the summit more than 12 centims. |^ 



Again, if in a jet flowing downwards and withdrawn from 

 every external influence, the tension caused by the acceleration 

 of velocity were the cause of disunion, the length of the conti- 

 nuous part ought to be independent of the diameter of the orifice. 

 For under the same charge, the total tension between two con- 

 tiguous strata of molecules, and the total cohesion which unites 

 the same, will evidently each be proportional to the number of 

 molecules which compose these strata. If, therefore, for any 

 orifice, and at a given distance from the same, the tension were 

 equal to the cohesion, so that the adhesion between two strata 

 was overcome, the same ought to take place at the same distance 

 in a jet issuing under the same charge from a larger or smaller 

 orifice ; for at this distance the increase of velocity would be the 

 same as in the first jet, and the total actions of tension and co- 

 hesion would have both increased or diminished in the same pro- 



