WITHDRAWN FROM THE ACTION OF GRAVITY. 263 



into the tube. By this arrangement, if all parts of the apparatus have beeu 

 carefully fiuishcil, when once the little nuts have been screwed up, the two 

 strips of glass can only move simultaneously in a par-allel direction to each 

 other, and always identically in the same direction perpendicular to the plate 

 of glass. When the liquid cylinder is well formed, and the weights are placed 

 upon the free portions of the copper wires, the linger is passed under the hori- 

 zontal branch of the fork, and the movable system is raised to a suitable dis- 

 t:iuce above the plate of glass; it is then maintained at this height by means 

 of the thumb-screw, so as to allow the result of the transformatiou of the cylin- 

 der to be observed. As the amalgamation of the copper wires always extends 

 slightly upon then- convex surface, the latter is coated with varnish, so that 

 the amalgamation only occurs upon the small plane section. It Avould be 

 almost impossible to judge by simple inspection of the exact point at Avhich the 

 separation of the copper wires from each other, to allow of the liquid attaining 

 a cylindrical form, should be discontinued. To avoid this difficulty, the length 

 of the cylinder is given beforehand, and this length is marked by two faint 

 scratches upon the lateral surface of one of the strips of glass ; the weight of 

 the globule of mercury, which is to form a cylinder of this diameter and of the 

 length required, is then determined by calculation from the known diameter of 

 the wire; lastly, by means of a delicate balance, the globule to be used in the 

 experiment is made exactly of this weight. All that then remains to be done 

 is to extend the little mass until the extremities of the copper wires between 

 which it is included have reached the marks traced upon the glass. Lastly, in 

 making a series of experiments, the same mercury may be used several times 

 if the isolated spheres ai"e united into a single mass at the end of each observa- 

 tion. However, after a certain number of experiments, the mercury appears to 

 lose its fluidity, and the mass always becomes disunited at some point, in spite 

 of all possible precautions, before it has become extended to the desired length, 

 which })henomena arise from the solfd wires imparting a small quantity of cop- 

 per to the mercury. The latter must then be removed, the plates of glass and 

 the strips cleaned, and a new globule taken. The amalgamation of the wires 

 also sometimes requires to be renewed. 



52. By means of the above apparatus and methods, I have made a series of 

 experiments upon the transformation of the cylinders ; but before relating the 

 . results, it is requisite for their interpretation that we should examine the phe- 

 nomenon a little more closely. 



Let us imagine a liquid cylinder of considerable length in proportion to its 

 diameter, and attached by its extremities to two solid bases ; let us suppose 

 that it is effecting its transformation, and let us consider the figure at a period 

 of the phenomenon anterior to the separation of the masses, ^. c, when this 

 figure is still composed of dilatations alternating with constrictions. As the 

 surfaces of the dilatations project externally from the primitive cylindrical sur- 

 face, and those of the constrictions on the contrary are internal to this same 

 surface, we can imagine in the figure a series of plane sections perpendicular to 

 the axis, and all having a diameter equal to that of the cylinder; these sections 

 will evidently constitute the limits which separate the dilated from the con- 

 sti'icted portion, so that each portion, whether constricted or dilated, will be 

 terminated by two of them ; moreover, as the two solid bases are necessarily 

 part of the sections in question, each of these bases should occupy the very 

 exti'emity of a constricted or dilated portion. This being granted, three hypo- 

 theses present themselves in regard to these two portions of the figure, i. c, to 

 those which rest respe<-tively upon each of the solid bases. In the first place, 

 we may suppose that both of the portions arc expanded. In this case each of 

 the constrictions will transfer the liquid which it loses to the two dilatations 

 immediately adjacent to it ; the movements of transport of the liquid will tdke 

 place in the same manner throughout the whole extent of the figure, and the 



