3 I2 



COMPARISON OF RESISTANCES. 



Putting 



(5) 



we obtain a new system of equations, which we may write 



(3)' 



(3)" 



a 2 -0-1 = 0-3- a-2 + A ' 2 



- etc 



The same subtraction taken inversely will give the same equations 

 with the opposite signs. The whole of the two systems of equations 

 may be represented synoptically by a table the symmetry of which 

 is evident. 



Ol -a 



o 



+A; 



3 -a 2 



-A; -A'; 



+ A/ 



-A' 2 ... -A<f-3) -A<- 2 > 



-*> ... 



The sum of the terms of the first vertical column being zero, 

 the sums of successive vertical columns give 



(6) 



