412 SCIENTIFIC WRITINGS. 



molecule or from space-element to space-element, and 

 we should then be warranted in applying the laws for 

 the molecular transference of heat, electricity, and elec- 

 trostatic distribution to magnetism also. 



This theory on its side compels us to assume, 

 that magnetism, like the electric current and electric 

 distribution, can only exist in closed circuits, in which 

 the magnetic i "moment" is inversely proportional to 

 the resistance of the circuit. This consideration leads 

 therefore to the introduction of the notions "resistance 

 to magnetic distribution" and "magnetic conductivity" 

 of space and magnetic bodies. According to this, only 

 so much magnetism can be produced in an iron rod 

 by an electric current circling round it as can be 

 conveyed from one to the other pole, or absorbed by 

 the space surrounding the iron rod. My experiments 

 have confirmed this view, and their result shows that 

 the magnetic conductivity of soft iron is approximately 

 500 times as great as that of non- magnetic matter 

 and empty space. 



Accordingly in the construction of electro-magnetic 

 machines Ohm's law may be applied for ascertaining 

 the most suitable dimensions, which will in many cases 

 be useful to the electrical engineer. The notion first 

 introduced by me, so far as I know, of magnetic con- 

 ductivity has meanwhile often been employed and 

 further developed in technical works - - without any 

 reference however to my priority. 



The attempt described in my work on the sun's 

 potential, to refer certain meteorological phenomena to 



