Rheostat question

I think some of the confusion may come from the fact that one side of the rheostat circuit is its metal frame. There are various ways to hook it up that will work; but here’s one way: The current flows through a wire from the positive battery terminal to the back-right terminal (the one with the asbestos insulation) The current flows through some part of the resistance wire wound on the ceramic core, then into the wiper that touches the resistance wire underneath, then through the switch (if it is on), then through one of the rods that the switch slides on, then through the metal base, to the right-front terminal. From there the current flows through another wire to the lockon terminal that connects to the center rail, then through the pickup into the locomotive, then out through the wheels to the outside rail and back to the other lockon terminal. From there the current flows through another wire back to the negative battery terminal, through the battery and back out to the positive terminal, where it started.