Mystery Movement... what do you think gents?

Wow... this thing is pretty cool.  I just picked this up in a lot tonight.  I don't have it in hand yet. 

Bulova Watch Co.

3 Adj

15 Jewels

Serial number "54377"  maybe?

"AT" movement?!?!?!  ONLY "AT" ?

No date stamp that I see.... but seems to be a makers/forge mark next to the "swiss"?  Looks like a triangle with something in it.

I'm thinking this one maybe pretty old.

Posted December 31, 2011 - 10:43pm

Club 5000Panel Member

Also... it's about the size of a 10AN movement for comparison.

Posted December 31, 2011 - 11:03pm

Club 5000Panel Member

These are from the early 20s, so it'll be 1921, 22, 23 era, normally seen in the ladies watches.

Reverend Rob's picture
Reverend Rob
Posted January 1, 2012 - 12:23am

Panel Member

 That is an AS 340, it started in the first half of the 20's and versions were still made into the early 40's. It is a very common movement, and Bulova called it the 10B and 10 AL, although there may have been other variants. I've fixed quite a few of these. The AT came in two sizes, one was 10.5''' and the other was a pocket watch, 19.5''', called the 19AT. It looks like the 10AT is also a Bulova name for the AS340 series ebauches. 

Posted January 2, 2012 - 4:03am

Club 5000Panel Member

So the AI equates to a 10AL?

I've seen alot of these early AI movements.

timerestoration's picture
Posted January 3, 2012 - 4:51pm

I have several of these Movements. It is A.I. 

not A.T. or A.L.

Reverend Rob's picture
Reverend Rob
Posted January 3, 2012 - 6:05pm

Panel Member

 I did some more checking, the 10AL and 10B are indeed an AS 340, but the 10AT and 10AI are made by FHF, and are different movements.  I can confirm that the movement in your picture is an AS340. The FHF 32 (10AT) is listed as a 7.75''' movement and has a different train bridge shape, according to its original technical documents. This would suggest that it is not an AT, so that jives with what timerestoration has said. All my 340's look exactly like the picture, and I have dozens. The OP pic does look like it is stamped 10AI. In later years, ebauche makers under the ESA umbrella manufactured identical movements and some were indeed double stamped, (ie., FHF/ST, or AS/ST) but this would be very early for that. Pardon the deviation into minutia, but my own fascination is with the evolution of the movements and the companies that produced them. It is also possible that my documents are incorrect, and I need to know if there are errors in them. 

edit: I have found several AI's and they are 340's. Weird, because Bestfit lists them as being different. 

William Smith's picture
William Smith
Posted January 12, 2012 - 2:49pm

Club 5000Panel Member

minutia = details = data = good for research.  I'm just happy your willing to put this much time/effort into your posts.

Posted January 3, 2012 - 7:48pm

Club 5000Panel Member

Thanks, so 10AI is correct.