"Yes. The wires have no ground-connection out-
side of the cave. They go out from the positive brush
of the dynamo; there is a ground-connection through
the negative brush; the other ends of the wire return
to the cave, and each is grounded independently."

"Nono, that won't do!"

"Why?"

"It's too expensive -- uses up force for nothing.
You don't want any ground-connection except the one
through the negative brush. The other end of every
wire must be brought back into the cave and fastened