. The London, Edinburgh and Dublin philosophical magazine and journal of science . ich meetin a point) into the Plateau configuration (fig. 1), with thelittle curve-edged square in the plane perpendicular to thedetermining force, which may now be annulled, as we nolonger require it. The rigid edges of the cubes may also benow annulled, as we have done with them also ; because eachis (as we see by symmetry) pulled with equal forces in oppo-site directions, and therefore is not required for the equi- * To do for every point of meeting of twelve films what is done by-blowing in the experiment of
. The London, Edinburgh and Dublin philosophical magazine and journal of science . ich meetin a point) into the Plateau configuration (fig. 1), with thelittle curve-edged square in the plane perpendicular to thedetermining force, which may now be annulled, as we nolonger require it. The rigid edges of the cubes may also benow annulled, as we have done with them also ; because eachis (as we see by symmetry) pulled with equal forces in oppo-site directions, and therefore is not required for the equi- * To do for every point of meeting of twelve films what is done by-blowing in the experiment of § 5. 506 Sir W. Thomson on the Division of Space librium, and it is clear that the equilibrium is stable withoutthem*. * The corresponding two-dimensional problem is much more easilyimagined; and may probably be realized by aid of moderately simpleappliances. Between a level surface of soap-solution and a horizontal plate of glassfixed at a centimetre or two above it, imagine vertical film-partitions tobe placed along the sides of the squares indicated in the drawing (fig. 2):. Fig. 2. these will rest in stable equilibrium if thick enough wires are fixed ver-tically through the corners of the squares. Now draw away these wiresdownwards into the liquid: the equilibrium in the square formationbecomes unstable, and the films instantly run into the hexagonal forma-tion shown in the diagram ; provided the square of glass is provided withvertical walls (for which slips of wood are convenient), as shown in planby the black border of the diagram. These walls are necessary to main-tain the inequality of pull in different directions which the inequality ofthe sides of the hexagons implies. By inspection of the diagram we seethat the pull is T/a per unit area on either of the pair of vertical wallswhich are perpendicular to the short sides of the hexagons; and on eitherof the other pair of walls 2 cos 30° X T/a; where T denotes the pull of thefilm per unit breadth, and a the side of a s
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