ClipArt ETC
"When the brass plugs are inserted...the coils are short-circuited, i.e., practically, the whole of a current passing from block to block goes through the plug, but when a plug is withdrawn the current passes through the corresponding coil...By withdrawing the proper plugs, one may throw into the circuit and resistance desired, from a single ohm up to the full capacity of the box." -Avery 1895

Resistance Box

"When the brass plugs are inserted...the coils are short-circuited, i.e., practically, the whole of…