805 



and on the right of the four-phase line in question. 



The reproduction of tiiese figures 8, 9, 10, wiiicii were not published 

 by Dr. Scheffer, seemed desirable to ine, because though they 

 do not contain anything new, they can render good services in the 

 application on account of their great lucidity. 



We can now represent the four-ptiase lines schematically for the 

 different cases. 



Fig. la agrees with the case considered in fig. 1. Particularities do 

 not present themselves; it is only worthy of note that the four- 



H 



