'46 Mercury horn wiring question

[Bruce_MO]

I'm restoring my '46 Mercury horns... it has the earlier style trumpet horns mounted on the inner fender on the driver's side. When I stripped back the original cloth loom over the wires to the horn relay at the horn mounting bracket, I was surprised to see what looks like a jumper wire soldered across the two posts (across the heavier gage yellow wire and smaller gage blue/yellow tracer wire from horn button). Third post on the relay has two clips for wires sending power "out" to energize the horns. I'm pretty sure that all the wiring was original. That jumper makes no sense to me. And the horns worked when the car was last driven before I stored it.

I'm not an expert on electrical wiring, but I was expecting 6V negative (yellow wire) into the relay, along with the blue/yellow tracer wire from the horn button, and then the two wires out of the relay to the horns. I thought when you pushed the horn button, you grounded it and completed the circuit to energize the relay and send current to the horns. It seems to me that the jumper wire would mess that all up.

Any ideas how this is supposed to work? Thanks in advance.