Connexion between the Units of Magnetism and Electricity, 79 



at each extremity of its swing ; but if it is naturally too quick ; 

 it will receive an outward impulse at each extremity. If its 

 natural rate is sometimes too quick and sometimes too slow, 

 according to temperature, it must therefore either gain or lose 

 (practically it would probably always lose) an odd number of 

 seconds when the temperature passes through the critical 

 value. 



XIII. On the Connexion between the Units of Magnetism and 

 Electricity. By Prof. R. Clausius*. 



IN a paper published in March of this yearf, I made some 

 remarks upon the systems of measures to be employed 

 for the measurement of electric and magnetic quantities ; and 

 therein one point occurs which has given occasion to various 

 objections — namely, the determination of the unit of magnetism 

 in the electrostatic system. Some of these objections, which 

 appeared in the June Number of the l Philosophical Maga- 

 zine,' I have already replied to in the August Number of the 

 same journal. Since then, however, some further remarks, 

 proceeding in part from parties worthy of high regard, have 

 been made ; so that I think it necessary again to introduce 

 the subject. 



In former times magnetism was regarded as an agent exist- 

 ing apart, independent of electricity. If that view were still 

 adhered to, it would not be necessary, in establishing a system 

 of measures for magnetism, to take into consideration the 

 system employed for electricity. It is, however, Ampere's 

 great merit, and, I believe I may add, one of the greatest 

 advances made by physics, that an indissoluble connexion 

 between electricity and magnetism has been demonstrated ; so 

 that we no longer need to consider magnetism a separate 

 agent, but can regard all the forces usually called magnetic 

 as electrodynamic. 



For if we imagine, in a given magnet of measurable mag- 

 nitude, each of the innumerable little magnets of which it 

 consists replaced by a small electric current of which the defi- 

 nition is that the product of the current-intensity and the area 

 round which the current flows is equal to the product of the 

 length of the little magnet and the strength of its poles, or, 

 differently expressed, equal to the magnetic momentum of the 

 little magnet, then the totality of these small currents exerts 



* Translated from a separate impression, communicated by the Author, 

 from Wiedemann's Annalen, xvii. (1882) pp. 713-719. 



t Verhandl. desnuturhist. Vereinsderpreuss. Rheinlande undWestfalens, 

 xxxix. p. 105 j Phil. Mag. June 1882, p. 381; Wied. Ann. xvi. p. 529 (1882). 



