WITHDRAWN FROM THE ACTION OF GRAVITY. 641 



pose of receiving the nuts which fix the strips to the system by 

 means of which they are elevated. This system is made of iron ; 

 it consists, in the first place, of two rectangular plates, 55 millims. 

 in length, 12 in breadth and 3 in thickness. Each of them is 

 pierced, perpendicularly to its large surfaces, by two holes, so 

 situated, that on placing each of these plates transversely upon 

 the extremities of the two strips of glass, the screws with which 

 the latter are furnished fit into these four holes. The screws 

 being long enough to project above the holes, nuts may then be 

 adapted to them, so that on screwing them the strips of glass 

 become fixed in an invariable position with regard to each other. 

 The holes are of an elongated form in the direction of the length 

 of the ii'on plates ; hence, after having loosened the nuts, the 

 distance between the two strips of glass may be increased or 

 diminished without the necessity of removing the plates. A ver- 

 tical axis, 5 centims. in height, is implanted upon the middle of 

 the upper surface of each of the plates ; and the upper extremi- 

 ties of these two axes are connected by a horizontal axis, at the 

 middle of which a third vertical axis commences ; this is directed 

 upwards, and is 15 centims. in length. The section of the latter 

 axis is square, and it is 5 millims. in thickness. When the nuts 

 are screwed up, it is evident that the strips of glass, the iron 

 plates, and the kind of fork which connects them, constitute an 

 invariable system. The long vertical axis serves to direct the 

 movement of this system ; with this view, it passes with very 

 slight friction through an aperture of the same section as itself, 

 and 5 centims. in length, pierced in a piece which is fixed very 

 firmly by a suitable support 10 centims. above the plate of glass. 

 Lastly", the perforated piece is provided laterally with a thumb- 

 screw, which allows the axis to be screwed into the tube. By 

 this arrangement, if all parts of the apparatus have been care- 

 fully finished, when once the little nuts have been screwed up, 

 the two strips of glass can only move simultaneously in a 

 parallel 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 finger is passed 

 under the horizontal branch of the fork, and the moveable system 

 is raised to a suitable distance 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 transformation of the cylinder 



