> It used 35mm movie film And why was movie film 35mm wide? It seems an odd width. William Dickson was going for a frame 1 inch wide, then added 3/8" for the s

> It used 35mm movie film And why was movie film 35mm wide? It seems an odd width. William Dickson was going for a frame 1 inch wide, then added 3/8" for the sprocket holes. The original specification was in Imperial units: 1 3/8" (34.925mm). I don't know when or why its name turned to metric. "At the end of the year 1889, I increased the width of the picture from 1/2 inch to 3/4 inch, then to 1 inch by 3/4 inch high. The actual width of the film was 1 3/8 inches to allow for the perforations now punched on both edges [...]." --- https://archive.org/stream/journalofsociety21socirich#page/450/mode/2up https://archive.org/stream/journalofsociety21socirich#page/4... To go back further, we would have to ask, why is an inch an inch?