WITHDRAWN FROM THE ACTION OF GRAVITY. 639 



less restrained and more regular conditions in some respects 

 than those of the preceding exjieriment, and which will more- 

 over lead us to new consequences as regards the laws of the 

 phaenomenon. We shall first succinctly describe the apparatus 

 and the operations, and afterwards add the necessary details. 



The principal parts of which the apparatus consists are, — 1st, a 

 rectangular plate of plate-glass, 25 centims, in length and 20 in 

 breadth ; 2nd. two strips of the same glass, 13 centims. in length 

 and 5-6 millims. in thickness, perfectly prepared and polished 

 at the edges ; 3rd, two ends of copper wire, about 1 millim. in 

 thickness and 5 centims. in length ; these wir-es should be per- 

 fectly straight, and one extremity of each of them should be cut 

 very accurately, then carefully amalgamated. The plate being- 

 placed horizontally, the two strips are laid flat upon its surface 

 and parallel with its long sides, so as to leave an interval of 

 about a centimetre between them ; the two copper wires are 

 then introduced into this, placing them in a right line in the 

 direction of the length of the strips, and in such a manner that 

 the amalgamated extremities are opposite to, and a few centi- 

 metres distant from each other. A globule of very pure mer- 

 cury, from 5 to 6 centims. in diameter, is next placed between 

 the same extremities ; the two strips of glass are then ap- 

 proximated until they touch the wires, so as only to leave be- 

 tween them an interval equal in width to the diameter of these 

 wires. The little mass of mercury, being thus compressed late- 

 rally, necessarily becomes elongated, and extends on both sides 

 towards the amalgamated surfaces. If it does not reach them, 

 the wires are made to slide towards them until contact and ad- 

 hesion are established. The wires are then moved in opposite 

 directions, so as to separate them from each other, which again 

 produces elongation of the little liquid mass and diminution of 

 its vertical dimensions. By proceeding carefully, and accom- 

 panying the operation with slight blows given with the finger 

 upon the apparatus to facilitate the movements of the mercury, 

 we succeed in extending the little mass until its vertical thickness 

 is everywhere equal to its horizontal thickness, i. e. to that of 

 the copper wires. Thus the mercury forms a liquid wire of the 

 same diameter as the solid wires to which it is attached, and 

 from 8 to 10 centims. in length. This wire, considering the 

 small size of its diameter, which renders the action of gravitation 

 insensible in comparison with that of molecular attraction, may 



2x2 



