I have seen just about all possible combinations of scratched serial numbers, both on standard L et S lenses and the known UK users of their glass (Shew and Long) but the outer surfaces seem to be most common.

There was a lot of variation in refractive indices in delivered glass blocks to lens makers. I only have knowledge from the workshop photos which were made which show shelves of glass blocks of different diameters. I don't think we have enough data to find out whether there were production series of the same Petzval/Landscape size with consecutive serial numbers. We know from Dallmeyers record that this was certainly the case with this larger volume maker who made to stock, rather than pressing customer demand.

The concept of having a number of curve formers for all of surfaces (8 in all) to allow for variation in two types of glass sounds like a production nightmare, but our "resident experts" must explain how it could be done?