160 HOUSTON, KENNELLY — THE PATH OF A CURRENT. [Mar. 19, 



vides into two metre blocks, each with half the density and each 

 with its attendant magnetic flux, as represented by the straight and 

 curved arrows of Fig. 21. Instead, however, of pursuing their 

 paths as sharply defined blocks, the two blocks are subjected to 

 attenuation by leaving stragglers or remnants along the road, since 

 the insulator is somewhat leaky. That is to say, the path through 

 which they pass is strewed with reflected or oppositely directed 

 electric flux, of reduced density, which immediately turns around 

 and moves back towards the centre of the line with the velocity of 

 light in that medium. Consequently, the two metre blocks undergo 

 a process of decay ; their density is diminished ; their energy is 

 dissipated in the insulator as heat, and in "supplying the straggling 

 reversed fluxes ; and the distribution, instead of being in planes 

 perpendicular to the cable, is bent backwards in a manner which is 

 exaggerated in Fig. 21. In fact the flux behaves as though it got 

 entangled in the insulator instead of moving freely through it, and 

 by reason of the entanglement^ a number of shreds or straggling 

 particles are detached from the advancing main body. If the leak- 

 age be sufficiently great, the blocks of flux may be completely dis- 

 sipated before they arrive at the termini of the line, the degree of 

 attenuation depending entirely upon the amount of leakage. 



Fig. 22, represents the condition of affairs at a later stage of the 

 first outward movement of the flux blocks. Here Vj v'2, represent 

 the movement of the heads of the columns ; U2 and u'2, represent the 

 backward movement of the stream of stragglers thrown off by the 

 heads in the course of their motion. Consequently, the entire 

 field between the two separating heads is filled with a confused 

 and straggling mass of attenuated flux, and a very complex state of 

 aff'airs is reached. The original blocks are entirely absorbed after 

 they have traveled a greater or less distance. 



We may next assume that the insulator insulates perfectly, 

 but that the wires do not conduct perfectly. This is a condition 

 which is very nearly represented in many practical cases. In 

 Fig. 23, the metre block of flux starts from the centre as before. 

 The interior conductor being positively, and the sheath nega- 

 tively, electrified. The curved arrows represent the direction of 

 accompanying magnetic flux, produced as soon as the motion 

 takes place. Here the imperfect conduction of the wire sets up a 

 series of straggling reflections of electric flux, in the same direc- 

 ion, however, as that in the moving blocks, instead of the oppo- 



