Jaime Swann is a machinist and framebuilder in Long Island, NY and knowledgable about NYC area early framebuilders. Contacting him might get results. Some mysteries like this one may be extremely difficult to solve. For example in my hometown of Niles, Michigan (just above South Bend, Indiana) was a frame builder around the turn of the century. In the City business directory it mentions he did silver and gold lug plating and showed a bike at the Chicago Exposition in the late 1800's. I can't find any more information about him at all. I'm sure there are other now invisible builders that are possible candidates as the maker of this frame.