This is a project we just finished (incarnation #1 of a 2 column water
computer). Historical references to select water computers from the past.
This design was engineered to be both analog and digital.

http://creative-automata.com/2014/12/18/hybrid-water-computer/




Paul Fishwick, PhD
Chair, ACM SIGSIM
Distinguished University Chair of Arts & Technology 
   and Professor of Computer Science
Director, Creative Automata Laboratory
The University of Texas at Dallas
Arts & Technology
800 West Campbell Road, AT10
Richardson, TX 75080-3021