Hi Don,
Do you have any paper that suggests how much earlier than 1940's? Does the collection have provenance-proving documentation? Was it a gift from Bull's family?
If Bull died in 1880, then this style of glass is unlikely actually to have been owned by him personally.
Owned/bought by a surviving family member is more likely.
One of the greatest problems is when folks arrive and say "Oh, it must be old, grandma died when she was ninety" and follows with "and I'm twenty-nine"... meaningless info, grannie dies at ninety, surfed the internet until 2005 and 363 days, but bought it the year before she died, at TK Maxx..... That does not, by any means, suggest the item is perhaps seventy years old, but it may well be more than seven days.......... This is where thorough research, not taking witness testimony, comes into play.
Provenance is now a major factor in any type of identification. You need receipts, gallery records, etc, artists, records..... all else is mere speculation, particularly with such an indistinct signature.
If Bull bought this, or indeed, received it as a gift, there may still be records of where and when. However, as a professional, I do not envy you the task of tracing that information.
Regards,
Marcus