I was in a printing mood the other morning so just picked through one of the negative files and shone some light through the first thing that caught my attention:
The negative is huge, by the way - I measured it 11.5cm x 7cm. This was almost a contact print on 10x8 paper, the enlarger head was very low to the base even with an 80mm lens. Allowing for some latitude with regard to the negative border, which was a bit hard to identify, it still seems an unusual negative size - very wide compared to the height. A Google search gave me this site: http://www.earlyphotography.co.uk/site/sfs.html which seems to list every film size known to man (and then some). It's not an exact match, but the closest I could get to this one was 2 1/2" x 4 1/4" (616 in Kodak-speak), which appeared in 1932 and therefore would seem to fit.
When I have access to a few of these great old negs in different formats - 6x6, 6x7, 6x9, the odd strange one like above and then some 4"x5" large format, it is really, really hard to even look at a 35mm neg. 35mm is so small by comparison - it's a toy format in the darkroom, really! I recall reading on Andrew Sanderson's blog that at one time he saw himself never using 35mm again, so content he was printing with larger formats. But then at some point in the future he 're-discovered' 35mm and shot away quite happily with it. Like a lot of stuff, it's horses for courses.