THE 



LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 



JUNE 1882. 



XLIX. On the different Systems of Measures for Electric 

 and Magnetic Quantities. By Prof. R. Clausius*. 



EOR the measurement. of electric and magnetic quantities, 

 it is well known that two essentially different systems, 

 usually called the electrostatic and the electromagnetic, are em- 

 ployed. Both reduce the determination of electric and mag- 

 netic quantities to the measurement of mass, length, and time; 

 but in the manner of the reduction they differ from each other 

 more considerably than is usually the case with other diffe- 

 rent systems of measures. While in the ordinary mechanical 

 quantities (such as velocities, forces, and mechanical work) 

 the different measuring-systems employed are distinguished 

 from one another only by the so-called fundamental units, viz. 

 the units of mass, length, and time, having different values, in 

 the two above-mentioned systems applied to electricity and 

 magnetism the formulce which serve for the determination of 

 one and the same quantity are also different, since they con- 

 tain different powers of the fundamental units. 



The deduction of these formulas is systematically carried 

 out with singular completeness in Clerk Maxwell's splendid 

 work, 'A Treatise on Electricity and Magnetism,' Oxford, 

 1873; and the high estimation in which Maxwell is justly held 

 could not fail to cause his formulas not only to be accepted in 



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

 from the Verhandl. des naturhist. Vereim der preuss. Rheinlande und West- 

 falens, vol. xxxix. (1882). Head at the meeting of the Niederrheinische 

 Gesellschaft fur Natur- und Heilkunde, on the 6th March, 1882. 

 Phil. Mag. S. 5. Vol. 13. No. 83. June 1882. 2 G 



