What is printed inside the triangle on the left of the 17 jewel movement? I have 17 jewel 5PPI with a similar triangle with "20" printed inside
Here is a 17 jewel 6PPI 1922, serial number 8925
How did we determine 17j w/ SN 8925 was from 1922?
The hallmark theory is all We have at this time for non Cased Movements not bearing Bulovas' published method for Date of production: http://www.mybulova.com/sites/default/files/image/Bulova-Year-Marking.gif
Movements hallmarked 'Bulova W. Co.' Date to 1922 and prior.
Movements hallmarked 'Bulova Watch Co.' Date to 1923.
In 1924 the published method initiates and all Bulova Movements bear the 'Bulova Watch Co.' hallmark .
Possibly, but these movts were used til the late twenties. The calibres are Aurore-Villeret 8.
Thanks Rob. Second example below has the latter Bulova Watch Co. signature (but a lower serial number- go figure). First example has the earlier Bulova W. Co. signature. By 1924 we see the asterisk date symbol, so perhaps 1923 for second example and 1922 for first example? We don't know the "date" the movement signatures changed, or if there even was a "firm date" for change. Their may have been an overlap of date of signatures.
Second example. Again no known year, but based on hand/dial on movement, c1924 or earlier??
Start Year was forced number entry, so i couldn't enter unknown. 1924 start year a guess.