The following is from "The Historic Bottle Website" by Bill Lindsey and others ...
The picture below shows a Hutchinson type bottle that used the Roorbach ball stopper. The bottles were produced by a method that required the use of an applied finish until well into the 20th century which is long after virtually all other bottle types were being mouth-blown with tooled finishes. According to one author the mouth-blown bottles were produced as follows ...
After being mold blown the bottles were sheared at the neck and allowed to cool. Then a glass marble, made from glass of a hardness twice that of the bottle was dropped into it. The bottle was then re-heated and the neck welded on (finish applied), so containing the marble (Goodacre 1995).