HERMANN VON HELMHOLTZ 



conductors carrying currents, and he showed that 

 the action of a small closed current at a distance is 

 the same as that of a small magnet placed in the 

 centre of the closed circuit, provided that the axis 

 of the magnet is at right angles to the plane of 

 the closed circuit, and that its magnetic moment is 

 equal to the product of the area of the closed 

 circuit into the current. This subject was extended 

 mathematically by Helmholtz. 



Helmholtz introduced a new method of research 

 into electrical questions by bringing in the idea of 

 convection in the distribution of electricity, that is, 

 the conveyance of electricity from one point to another 

 by the movement of the material elements carrying it. 

 It was important to determine whether or not the 

 magnetic effects of an electric current were identical 

 with those produced by the displacement of matter 

 carrying an electrostatic charge. The experimental 

 research on this subject was carried out in Helmholtz's 

 laboratory by the well-known American physicist, 

 H. A. Rowland, and the results were published in 

 1876. Electrical convection currents throw some 

 light on the movement of electricity in unclosed 

 conductors ; while in electrolysis the gases dissolved 

 in the fluid may also carry charges of electricity by 

 convection. It was proved that a revolving charged 

 conductor behaves like a ring-shaped electric current. 



With another American electrician, E. Root, 

 Helmholtz, also in 1876, examined the polarisation 



