It looks to me like an eastern Pennsylvania screw-tip horn that lost its original internal screw tip on the spout. Since the remaining spout section was already threaded, the owner simply made a threaded wood stopper to fit the surviving threads. That was probably a better seal for the horn, and a threaded stopper wouldn't/couldn't fall out if the horn was jarred too hard. It5's a neat way to fix a lost internal screw tip, using a little imagination.
Shelby Gallien
