Resistance-network analogues with unequal meshes or subdivided meshes

A general method for deriving the finite difference approximations to the partial differential equation div K grad U = g , which is solved by resistance-network analogues, is applied to find the resistance values and the currents which have to be fed in for ( x , y )- and ( r , z )-networks with unequal mesh sizes. Two ways of subdividing a network into finer meshes in the ratio 1: 2 are then given, and a network subdivision in the ratio 2: 5 is described. Experimental tests have shown that these subdivisions introduce negligible errors into the measured field distributions.