That reminds me of the hydraulic MONIAC computer [0]. ("Monetary National Income Analogue Computer")<p>Or perhaps the ancient greek"hydraulic telegraph" [0], which (sadly) was <i>not</i> a pipe-based communication system, but two independent pre-calibrated water-clocks. The signals were sent by flaming torch, but by measuring the duration of the light more information could be sent.<p>[0] <a href="https://en.wikipedia.org/wiki/Phillips_Machine" rel="nofollow">https://en.wikipedia.org/wiki/Phillips_Machine</a><p>[1] <a href="https://en.wikipedia.org/wiki/Hydraulic_telegraph" rel="nofollow">https://en.wikipedia.org/wiki/Hydraulic_telegraph</a>