Quote Originally Posted by Jerevan View Post
I don't understand much (or rather have little idea of the implications of the various schemes presented) but I am going to read anyway. Some things will stick, eventually. I assume the speed mentioned in fig. 1 and 2 (page 18 - 19) is not ASA/ISO?
Actually, you've precisely hit on the value of reading technical historical literature. Starting from the implications, and then circling back to specifics/facts, ideally coupled with some hands-on lab work, is exactly how historical sciences are best understood and recreated.

Re 'speed': The concept of speed, as we know it as a set of standardized values, is essentially meaningless with 'color blind' (i.e. sensitive to only UV light) emulsions. It wasn't until the 1930s and 40s that the research was done on emulsion sensitivity that was adopted by the American Standards Association. Until then, there were a half dozen different 'standards', but it is almost certain that Carroll and Hubbard were using the system of comparative speeds, based on gaslight papers as '1'.

From the Focal Encyclopedia of Photography, 1958: Material/Relative Speed
Contact papers and contact lantern plates/1
Slow chlorobromide papers/10-20
Fast chlorobromide papers and warm-tone lantern plates/50-100
Bromide papers and bromide lantern plates, positive films/100-500
High-speed pan film or plate/around 100,000.