Thank you ,thank you very much !!!
First , congratulations for splitting Rigel with a 42mm aperture ,that is really awesome!
Second, this is the information I was recollecting.
Now I understand where I was at mistake because I kept on looking and searching in the books of Lockyer.
Don't ask me why...
Oh , Kitchiner is an author very dear to my heart ,I printed his Astronomy and Optics books and read them.
Those pages are crammed with information , so it happen to remember an information but not the source.
Thank you for the details about the refractor ,clear sky , Mircea