362 Bumstead — Reflection of Electric Waves, etc. 



conductor ;'^ but the above considerations make it clear that 

 this is not the case. 



But an exactly analogous thing happens also when there is 

 no bridge, when the simple theory would not cause it to be 

 expected. Thus, suppose the wires to terminate in an infinite 

 plate having no electrical conductivity but infinite magnetic 

 conductivity ; we now have reflection of the opposite kind to 

 that in the previous case, for now the magnetic force will 

 vanish while the electrical force will remain ; and we shall 

 thus have a node for H and I and a loop for E and Y. If, 

 instead of having the magnetically conducting plate, we cut 

 the wires at this point, we have nearly the same effect ; for 

 infinite resistance in the wires is, as we have seen, approxi- 

 mately equivalent to infinite magnetic conductivity in the 

 medium. But the result is not quite the same, for the effect 

 of the termination of the wires is felt, at first, only in the parts 

 of the wave plane near the wire ; it is equivalent, not to an 

 infinite plane with magnetic conductivity, but to a little ring 

 of infinite magnetic conductance, immediately surrounding 

 oach wire. These little rings will immediately annul the mag- 

 netic force near the wire, but, as in the case of the wire bridge, 

 the more distant tubes of force must come in with the speed of 

 light and there is an entirely analogous delay and displace- 

 ment of the apparent node beyond the ends of the wires. The 

 shifting of the node should be about the same as in the pre- 

 vious case, as, in fact, it is found to be experimentally ; if any- 

 thing, it should be slightly less, for the imitation of a ring of 

 perfect magnetic conductance by cutting the wire is probably 

 closer than the approximation to a perfectly conducting bridge 

 when a copper wire is put across the guides. 



Yale University, New Haven, Conn. 



* E. g., Drude, Physik des Aethers, bottom of page 465. 



