Ever seen a Bonanza from Chicago, JLL?
It looks like it would run with a cleaning.
It resembles an Elgin model 2.

Doug

Could be a Swiss fake, but the jewels look legit. Not sure.

A good "swiss fake" copy of a "sorta Elgin-Illinois 18s"

The "dead-Giveaway";
1. Equi-spaced "balance weights".
2. Un-cut solid brass balance wheel.
3. Pressed in Hairspring stud (no set screw).

Note, the gold book comments that some American Waltham model 1857 Wm Ellery were marked "Bonanza". Your watch is not of that type, but it might "Run pretty Good" if cleaned.