WITHDRAWN FROM THE ACTION OP GRAVITY. 607 



must not stop here, for it will serve us as a starting-point in 

 obtaining other figures which we require. Apply the point of 

 the syringe to one of the above convex surfaces, and gradually 

 withdraw some of the liquid. The curvatures of the two surfaces 

 will then gradually diminish, and with care they may be ren- 

 dered perfectly plane. It follows from this first result, that a 

 plane surface is also a surface of equiUbrium, which is evidently 

 in conformity with theory. Let us now apply the end of the 

 syringe to one of these plane surfaces, and again remove a small 

 quantity of liquid. The two surfaces will then become simulta- 

 neously hollow, and will form two concave surfaces of spherical 

 curvature, the margins of which rest upon the metallic band, and 

 the curvatures of which are the same. Finally, by the further 

 removal of the liquid, the curvatures of the two surfaces become 

 greater and greater, always remaining equal to each other. 



Hence it results, first, that concave surfaces of spherical curva- 

 ture are still surfaces of equilibrium, which is also in accordance 

 with theory. Moreover, as the plane surface left free sinks 

 spontaneously as soon as that to which the instrument is applied 

 becomes concave, it must be concluded that the superficial layer 

 belonging to the former exerts a pressure which is counter- 

 balanced by an equal force emanating from the opposite super- 

 ficial plane layer, but which ceases to be so, and which drives 

 away the liquid as soon as this opposite layer commences to 

 become concave. Again, as further abstraction of the liquid de- 

 termines a new rupture of equilibrium, so that the concave sur- 

 face opposite to that upon which we directly act exhibits a new 

 spontaneous depression when the curvature of the other surface 

 increases, it follows that the concave superficial layer belonging 

 to the former still exerted a pressure, which at first was neu- 

 tralized by an equal pressure arising from the other concave 

 layer, but which becomes preponderant, and again drives away 

 the liquid when the curvature of this other layer is increased. 



Hence it follows, — 1 st, that a plane surface produces a pressure 

 upon the liquid ; 2nd, that a concave surface of spherical curva- 

 ture also produces a pressure ; 3rd, that the latter is inferior to 

 that corresponding to a plane surface ; 4th, that it is less in pro- 

 portion as the concavity is greater, or that the radius of the 

 sphere to which the surface belongs is smaller. These results 

 were also pointed out by theory, and had already been verified 

 in the application of the latter to li(piids submitted to the action 



