Bulova 1920 -Unknown

Interesting.  That would be a wierd break between serial numbers for two different cases/production runs.  If American Standard has set up a run of one case w/ a range of SN's, and a different case run w/ other numbers, I certainly wouldn't think their range break point between the two runds would start at 1000763.

Those numbers must mean something other than production runs.

The different logos Shield V Globe has to mean different dates, maybe only as little as months, but this shows we can't compare case serial number methods with other companies like Waltham or Elgin.

I don't think it does.  As a matter of strong opinion, and following suit of production methods of other watch makers, bicycle makers, vacuum machine makers, jewelry makers, candy bar manufactures, etc...,  I think they must be associated with production runs at minimum.  Otherwise how would those stamping the cases know which numbers to use?  We don't see duplicates in any of these case SN's.   Models could be assigned SN's in order , as evidenced by  most other case examples BUT there could be breaks in sequential ranges between models.  This one outlier we are discussing doesn't prove its out of order.  Its just a weird break. One example we would all like to explain.

There could be three "consecutive ranges" of serial number assigned as below:

"Joe (or machine, or factory, or floor of factory, or contracted case maker, etc...) make those Lone Eagle Cases"with numbers 1110000 to 1119999.

Mike (or machine, or factory, or floor of factory, or contracted case maker, etc...) make those President cases with number between 1120000 to 1129999.

Jane (or machine, or factory, or floor of factory, or contracted case maker, etc...) make those Lone Eagle Cases with numbers between 1130000 to 1139999.

This would account for a break in sequential ranges between models.

I'm sure Bulova didn't say:
Joe, you make Lone Eagle cases using serial number 1110922. 1110870 and 1112009.
Mike, you make President cases using serial numbers 1114299. 1110788 and 1111603.
Jane, you make Lone Eagle cases using serial numbers 1114298. 1110787 and 1112008

It's not like they said, "OK everyone, lets start making these cases and stamp them with what ever serial numbers you want".  Groups of numbers- in ranges- were assigned, and there was orchestrated order to these assignments, as evidenced by no duplicates.  In our database, many, if not most case SN's ranges have a correlation with case types/models, and we have an interesting outlier here which we are now discussing. We have other "sequential ranges" between models which are non-sequential within one model, but that's explained by my "Joe, Mike, Jane" scenario.

With or without seeing any look-up tables or Bulova production records or "hard evidence" if you will - I'm pretty sure Bulova followed the industry-wide or even manufacturing-wide standard protocol for production versus come up with some numeric system of there own  AND then talk their various case maker contractors to adhere to this non-standard system.  

It flyes in the face of manufacturing protocol acrosss the board.    But still- how do we explain this one case style number break?  

At minimum, serial number ranges are assigned to production runs.  It is the world wide SOP, otherwise, these numbers make little sense.   They could also have other meanings- like the first digit corresponding to year of production with a decade, as we see is true, and still follow this assigned range for production.

That would need ten case-making factories, or ten machines making cases. Very doubtful pre-1923. I've checked sn's from 1918-1922 on this site alone, more than thirty examples and we have the full digit run from zero to nine covered as the last numeral.

I'm still thinking all this through too. That one number break sure is surprising, but it is real- what ever it means.