(there was a url link here which no longer exists) - Taylor Taylor & Hobson Series XV Triple Convertible Anastigmat Design Paper
I received British Patent Number: 376044A after discussion with Mark Craig Gerchman, Chief Optical Designer of Cooke Optics Limited.
He says that patent reveal all the details of 1931 production Pre Ansel Adams lens.
After the post came to me , I found that some glasses made by Chance Brothers. I contacted with them and requested the details. They said they dont have the catalogs anymore. Later Mark sent me the details.
I will post the word file with different title below.
I sent mail to Mr.Gerchman after 4 years and Cooke Optics CEO sent me a sad message , that wonderful gentleman had died 3 years ago.
Rest in Peace my friend .
Chance Bros, of Birmingham was incorporated into Pilkington, which was for a while the largest glass producer in the world.
The last lens that I know for sure that contained Chance Bros glass was the Collapsible Summicron