Horn relay Help!

Working on wiring my Model A.
Have a older style Relay that I was planning on using. Has 3 terminals marked B, S, and L.
My first question is do I need a specific sort of relay for the horn since it is switching the ground I think?

And can anyone tell me how to wire this?

My first thought is the following

B = Battery 12v
S = Switch, black wire on my GM column
L = Load to the Horn

Any ideas?

Thanks as always.

 

I think you have down. Wire it that way on the bench with a test light instead of a horn. That way you will not wreck it if it's wired wrong.

 

xx2