[Coupeguy2001]

The spring pin rides on a upper brass ring that is part of the steering column upper bearing. It is supposed to be free, and the spring holds the contact pin against the brass ring.
There is a wire attached to it that goes to the negative side of the horn relay. In essence, when you push on the horn button, you ground out the ring, and the contact with the spring in it is the path the ground takes because the wheel turns, and can't use a piece of wire.
The thing that the horn button is attached to is the button "spring" if you will that returns the horn button to the no contact position.
So here's what happens:
1 you see an alarming situation, and your hand goes to the button.
2. the device that holds the horn button makes contact with the little spring contact that pushes into the little hole in the steering wheel and provides a ground.
3. the bottom of that pin contact rides on the brass ring, and transmits the ground to the upper bearing.
4. the upper bearing wire is connected to the harness that allows that grounded wire to go to the horn relay negative contact.
5. The horn relay has power to it all the time, so you just grounded the negative side of the coil.
6. the coil pulls in the relay, and allows the horn relay to provide 12 volts to the wire that goes to the horns.
7.The horns are grounded by their mounts, and the 12 volts activates the horn.