1935 horn wiring

[jdjj]

Does the horn only have one wire and to which terminal does it go? The one with the white dot or other one? I assume there is no ground wire since its grounded when horn button pushed? The bolt that holds horn on goes thru fender and has the rubber head light pad underneath, but does this ground any way since bolt contacts metal underneath fender? I have a 1934 sedan with terminals a little different, but it has a ground wire on one of the terminals. ??