Good question. Had to go back to the book to be able to give an adequate answer.
Should note that my "get rid of" list is in no way a form of negative criticism of these books. It's more that either they information they contain is redundant with what I have in other books, or that I've got out of them the little information that is (or was when I got them) useful to me.
The latter is the case with the Davis book. It's a fascinating book. I have a special fondness for theoricians. When I studied musicology and music analysis, I enjoyed spending months trying to analyse a Beethoven string quartet using Schenkerian analysis, or Stravinski's
Rite of Spring using Allen Forte's set theory and pitch class sets. The analogy is not perfect, but Davis kind of brings me back to the intellectual quests and pleasures of these student years.
Also, you cannot but develop a kind of admiration for a guy that looks Ansel and Minor in the eye and says: "Hold my beer."
All this said, truth is, when I go through the book, I see nothing there that could, at this point, help make me a better photographer —
even if it could make better at scientifically testing and analysing film and paper. At this point, the book — or rather, the theory — holds nothing that is useful to me. I mostly use two films, each has its dedicated developer, and when I opt for a different developer, it's one I know. I'm happy with my negs — they may sometimes be off by 1/3 stop, but they give me what I need to make a good print.
More importantly, at 63 (and I would have said the same 10 years ago), I don't have time for all the film and paper testing, or graph making and analysing, this, just to correct that 1/3 stop that I may be off by. Life's too short, and looking at the world trying to figure out what may possibily become an interesting photograph takes time enough. Not that I don't find important the scientific aspect of photography, but, as I said, I already have enough of that in the other books on my "keep" lists.
Davis' book, and theory, is interesting, but I do feel that it's more of a curiosity than a necessity. Sort of like Schenker and Forte.
Note that none of the books on my "get rid of" will find their way to the recycle bin. I'll probably end up giving them to my community darkroom library.