[bediger4000]

The coding for the optical telegraphs seemed primitive to me. I wonder if you couldn't come up with a system that mixed signals going both ways.

[oldjavacoder]

The semaphore tower method could maybe have supported mixed signals with one operator dedicated to receive/forward and the other operator dedicated to acknowledge with a detailed response.

[bediger4000]

A series of "glyphs" that mixed forward signals and backward signals would help. Old school "local loop" telephones electrically multiplexed signals, but the optical telegraphs were quite a bit more discrete.