The center hole is too small or at least its proportions don't match up with a CD. But in any case, how would you design a recording device? The text says ther

The center hole is too small or at least its proportions don't match up with a CD. But in any case, how would you design a recording device? The text says there were mostly cylinders and discs, which makes sense because you can put a spiral track on those. In the disc case you would have to rotate them around their Z axis which pretty much requires a hole in the center. So I guess it's not that surprising that Bell's cardboard-and-wax disc, vinyl records, laserdiscs and CDs all look pretty similar.