150 IIOUSTOX, KEXNELLY — THE PATH OF A CURREXT. [Mar. 19. 



interior wire, while the other conductor is the sheath of metal, 

 liquid or ground, and the medium through which the electric cur- 

 rent flows is the ether in the insulating coating of rubber, gutta- 

 percha, paper, etc., with which the interior conductor is invested. 



3. A pair of overhead wires supported sensibly parallel to each 

 other, on suitable insulating supports ; as, for example, a pair of tele- 

 phone or electric-light conductors. Here the two wires are the con- 

 ductors, and the medium through which the electric current flows is 

 the ether in the air between them. 



When an electric source is connected to any such pair of conduc- 

 tors, an electric flux is established in the insulator between them; or, 

 more correctly speaking, in the ether permeating the insulator. The 

 density of the electric flux, or the quantity of flux per normal square 

 centimetre, will depend upon the nature of the insulator, on its 

 dimensions, and on the electric pressure or voltage of the source. 

 An increase of voltage is attended by a proportional increase in 

 the density of the electric flux ; while an increase in the thickness 

 of the layer of insulating material between the conductors dimin- 

 ishes the density. Figs, i, 2, 3, are diagrams of the distribution 

 of electric flux for the three types of circuit mentioned. 





\ J- / ^ ^• 



tt.ttTtttttttttTttttTTtrTtT ,'' ^^ '^f^ ^^^^ 



tnttrtffttttTfttntttttTt / / / i J ^^ ^ ^ 



vsr (^ a- 



Fig. I.— Electric Flux Surrounding an Aerial Wire with Ground-Return Circuit. 



In Fig. T, AB, represents the aerial wire, and GG, the ground. 

 The flux stream-lines are represented on the right-hand side in a 

 plane perpendicular to the wire. These stream lines are arcs of 

 circles, on the supposition that the ground, GG, is conducting, and 

 has a level surface, such as might be presented by the surface of 

 water in a lake. On the left-hand side the flux is represented as 



