Very interesting and well done presentation but I’d like to add a few things to it. When the Academy changed the size of the film exposed area to allow for an optical track it changed only the film image aspect ratio from 1:33… to 1:37. This change in aspect ratio was done to account for theaters projecting the image from above the perpendicular center of the screen. Thus the image while 1:37 on the film would be distorted by the projection geometry to be 1:33… on the screen.
Things got a little further confused when SMPTE issued its film camera aperture standard (now SMPTE 59-1998). It includes nominal dimensions in both inches and millimeters. The aspect ratio using the millimeter dimensions is 1.375 whereas that using the inch dimensions is 1.37460…
As far as I can determine SMPTE considers the SI unit dimensions authoritative.