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Thank you for giving me some perspective on this, Bob. Salt makes a valid point (arguably). However, I have to agree with Mr. Farr that the current study of films from this era should be comparing actual shot length in footage and not in time (largely due to varied projection speeds and varied opinions on what those speeds should be!!). This fact, and whether they are examining a complete film, seems to define the present study as irrelevant (in my opinion).
I don't disagree with you, especially since many of the Keystones were trimmed for reissue. But Salt's examination of ASL is largely a matter of technological influence. His argument being that ASL did not perceptably change, from silence to sound to wide screen, despite all the technological innovations along the way. I think for Salt, though i certainly can't speak for him, the fact that the ASL for Chaplin, Lehrmann and Arbuckle wassay 5' and the ASL for Normand say was 6' he would only conclude that the overall ASL for these filmmakers would be 5.25' and I don't think he would draw any startling conclusion except to say that in general Mabel's ASL was longer that the ASL of the others--but still well within the overall ASL for the era.
As an editor, when i worked in live action, I actually counted the number of cuts per reel on several projects I worked on--and the number was 125-130 cuts per 1,000' reel. Now that is higher than average for the period, where the average was probably between 90-100 cuts per reel, but it's not way off the mark, and there were certainly times when I might have 6-10 cuts per reel due to the nature of the way the material was covered by the director, so my ASL would vary. This is why all such "objective" meaurements turn out only to be objective measurements of the material at hand. Cecil B. DeMille, for example, was primarily a "mise en scene" director who played scenes in relativle long mid-shot takes--except when he didn't due to the exigencies of the scene or the requirement of the action. The exceptions make for what is interesting in cinema, not the raw stats of whether DeMilles's ASL might have been 7 feet 8 frames, while Delmer Daves's ASL might have been 6 feet 2 frames--which proves absolutely nothing.