Hooked a ground wire to the ant. terminal.
It must be true, because as a kid I read the Disney saga "Land Beneath the Ground", wherein the underground Earth dwellers known as Terries and Firmies explained how radio broadcasts go deep underground via the stations' ground wires, and can be heard via certain magnetic rocks. Here's a thumbnail of the story, though it doesn't mention the ground wire reference..
https://en.wikipedia.org/wiki/Land_Beneath_the_Ground!