Recent addition of 5x7 inch Top-Handle Spd.Graphic to collection. Camera appears to be all-original. Ser. No. was scratched off long ago. Think dating lens may help.
It is: "5x8 Bausch & Lomb-Zeiss Tessar Series 1c No.1915639". Barrel-mount with 5-screw flange, board labelled 'B' in pencil on upper right corner. Serial number doesn't correspond to B & L serial no. records I have found. Can anyone help?

Good luck. There's one B&L chronology floating around on the internet. I won't give you directions to it because it is not consistent with the few B&L lenses I've been able to date crudely, e.g., pre-1915.

As far as I know no reliable B&L chronology is available. There's also no reliable Wollensak chronology.

Dan-I found the B&L s.n. list online. You're right. Doesn't help date B.&L.Tessar's made under license.