The style 3 Baby Ben has two types of base lettering on the bottom. Most of the bases are painted gold on the bottom, I've seen one painted black, on a case without a movement.
Base 2 "A.1"
Base 2 "A.2"
Base 2 "A.1" Black Bottom. Date unknown, the case has no movement. The clock may be from Canada.
Base 2:
Four USA patents with the last patent and "MADE IN U.S.A." contained in a raised rectangle. Starting in mid-1933.