The first attachment is from a 1908 British catalog and explains the numbering system on the original Swan eyedroppers, which were probably in use from the time the brand was introduced till at least 1910. At the end of 1907 the "Mabie, Todd & Bard" partnership was dissolved and "Mabie, Todd & Co." was incorporated in New York State.
Next is the explanation of model numbers from the 1921 Mabie, Todd New York catalog. As far as I've pieced together, the first self-fillers were introduced about 1915 and were numbered as "2 S.F.", "4 S.F." and I even have a "2½ S.F." I don't know whether this numbering system referred to the barrel ("holder") size or the nib size. By 1921 they had replaced that system with the one described below, which as I say looks like it developed directly into the more-familiar 1930s system.
I was disappointed in the quality of the scans but they're all that's available. (And I don't have the actual catalogs, no.) Any copyright on these documents has long since expired, so I'm not worried about reposting them.
Edited by MikeForester, 30 July 2012 - 05:11.