156 IIOUSTOX, KEXXELLY — THE PATH OF A CURRENT. [Mar. 19, 



by the flux rush is, therefore, reversed in direction, since the mag- 

 netic flux, by which it is measured, is reversed, but the electric 

 potential difference, as measured by the density of electric flux, 

 remains unaltered. The two metre blocks now rush towards the 

 centre of the line with the speed of light. They may be consid- 

 ered as solitary waves of light, that is to say, disturbances traveling 

 with the velocity of light waves, but not periodic, and leaving the 

 medium quiescent the moment they pass by. 



After the lapse of another ^q^Qpth of a second, the two metre 

 blocks, which will again arrive at E, the middle of the line, as shown 

 in Fig. II, where the two arrows v and v', indicate that the blocks 

 are about to collide. The curved arrows show that the magnetic 

 flux is oppositely directed in the two blocks, those on the left-hand 

 side at mm, being directed into the loop, as seen by the observer, 

 while those on the right-hand side at m^ii^, being directed out of 

 the loop. 



Fig. 11 m mm' dT 



C "^ ^^utUJH^ j^w\^ ^ ^Q 



m mm' m' 



Fig. 12 



E 



v^^ liiM "^ jj 



Fi<ll3 m, mm' m' 



-mm/ r^miuii'j ^-^ p 



Figs. 11-13. — CoUision^of Electric Flux Waves in Circuit of Perfect Conduction 

 and Insulation, 



In Fig. 12, the metre blocks are represented as having collided; 

 they have merged together and mutually annulled each other's mag- 

 netic flux. Consequently, there is no magnetic energy. On the 

 other hand, the density of electric flux being doubled, there will be 

 four times the electric energy per cubic centimetre. Consequently, 

 there are 1000 ergs of electric energy in the single metre block at 1000 

 volts pressure, just as in the original condition before the start, in 

 Fig. 5. The two blocks, however, pass completely through each 

 other, appearing on the opposite sides. 



