But out on the Sea time was counted up to 8 bells. And at midnight on New Year's Eve 16 bells would be struck - 8 bells for the old year and 8 bells for the new, I learn from Wikipedia.

On a chess board there are 2 'teams', the white and the black pieces. 16 + 16 = 32. Number 16 is twice 8, and number 16 can only be understood if this basic relationship is known.

Moon has 2 'faces' (phases), but the face of my wall clock is only one. Moon is waxing or waning depending on time. One side of her face is white and the other black.

I imagine they changed from 24 to 16 letters in the futhark because the inclination of the axis of Earth had declined from an original approximately 24º to a noticeably lower value:

This diagram I found in Wikipedia and 24º it was when the great pyramids in ancient Egypt were built. Later they must have noted with dismay how the tropic belt, the 'land' where Sun could reach zenith, slowly was decreasing as if Sun was growing old.