Ehcl iD-tnagiu'lical Apparatus. 28."i 



litllt' way into the mercury, and its lower end is amalgamated. 

 When the connexions are so made with the pillar and right 

 hand wire, that the current of electricity shall pass through this 

 moveable wire, it immediately revolves round the pole of the 

 magnet, in a direction dependant on the pole used, and the 

 manner in which the connexions are made. 



Fig. 5, is the delineation of a small apparatus, the wire in 

 which^ revolves rapidly, with very little voltaic power. It con- 

 sists of a piece of glass tube, the bottom part of which is closed 

 by a cork, through which a small piece of soft iron wire passes, 

 so as to project above and below the cork. A little mercury 

 is then poured in, to form a channel between the iron wire and 

 the glass tube. The upper orifice is also closed by a cork, 

 through which a piece of platinum wire passes, which is termi- 

 nated within by a loop ; another piece of wire hangs from this 

 by a loop, and its lower end, which dips a very little way into the 

 mercury, being amalgamated, it is preserved from adhering 

 either to the iron wire or the glass. When a very minute vol- 

 taic combination is connected with the upper and lower ends of 

 this apparatus, and the pole of a magnet is placed in contact 

 with the external end of the iron wire, the moveable wire within 

 rapidly rotates round the magnet thus formed at the moment ; 

 and by changing either the connexion, or the pole of the mag- 

 net in contact with the iron, the direction of the motion itself is 

 changed. 



The small apparatus in the plate is not drawn to any scale. 

 It has been made so small as to produce rapid revolutions, 

 by the action of two plates of zinc and copper, containing not 

 more than a square inch of surface each. 



In place of the ball and socket-joint, (fig. 3, and 4,) loops may 

 be used ; or the fixed wire may terminate in a small cup containing 

 mercury, with its aperture upwards, and the moveable wire may 

 be bent into the form of a hook, of which the extremity should 

 be sharpened, and rest in the mercury on the bottom of the 

 cup. 



