188-1.] on the Theory of Magnetism. 9 



external neutrality that we obtain in them when the polarities are 

 changing we know, from their structure, to be perfectly symmetrical. 



I was anxious to show some mechanical movement produced by 

 molecular rotation, consequently I have arranged two bells that are 

 struck alternately by a polarised armature put in motion by the 

 double polarised rod I have already described, but whose position, at 

 three centimetres distant from the axis of the armature, remains 

 invariably the same. The magnetic armature consists of a horizontal 

 light steel bar suspended by its central axle ; the bells are thin wine- 

 glasses, giving a clear musical tone loud enough, by the force with 

 which they are struck, to be clearly heard at some distance. The 

 armature does not strike these alternately by a pendulous movement, 

 as we may easily strike only one continuously, the friction and inertia 

 of the armature causing its movements to be perfectly dead-beat when 

 not driven by some external force, and it is kept in its zero position 

 by a strong directive magnet placed beneath its axle. 



The mechanical power obtained is extremely evident, and is 

 sufiScient to put the sluggish armature in rapid motion, striking the 

 bells six times per second, and with a power sufficient to produce 

 tones loud enough to be clearly heard in all parts of the hall of the 

 Institution. 



There is nothing remarkable in the bells themselves, as they 

 evidently could be rung if the armature was surrounded by a coil, 

 and worked by an electric current from a few cells. The marvel, 

 however, is in the small steel superposed magnetic wire producing 

 by slight elastic torsions from a single wire, 1 millimetre in dia-r 

 meter, sufficient force from mere molecular rotation to entirely replace 

 the coil and electric current. {Experiment shoivn hy ringing the 

 hells hy the torsion of a small ^^-inch wire placed 4 inches distant from 

 hell-hammer.) 



Correlation of Forces. 



There is at present a tendency to trace all physical forces to one, 

 or rather a variation of modes of motion. In my last experiment 

 the energy of my arm was transformed in the wire to molecular 

 motion, producing evident polarity; this, again, acted upon the 

 ether, putting the needle-hammer into mechanical motion. This by 

 its impact upon the glass bells transformed its motions into sonorous 

 vibrations; but this does not mean that we can convert directly 

 sonorous vibrations into magnetism, or vice versa. 



Let us take this soft iron rod ; it seems quite neutral, although 

 we know that the earth's magnetism is trying to rotate its molecules 

 to north polarity at its lowest extremity. We now put it in mecha- 

 nical vibration by striking it gently with a wooden mallet; the 

 molecules at once rotate, and we have the expected strong north 

 polarity. Let us repeat this experiment by employing heat, and here, 

 again, at red heat an equally strong north polarity appears. 



Again we repeat, and simply pass an electric current of no matter 



