Another area of this field of endevours is called Fluidics - it
makes use of the fluid properties of air (i.e. a stream of air
will cling to a surface). Actually pretty much anything you can
build in a digital circuit you can do with a fluidic circuit (bit
bulker of course). Same logic sets apply to both and the devices
do the same thing.
I remember that for an open house at tech school a couple of
guys built a coffee server using fluidics and pneumatics. You
could select by push button what you wanted in your coffee - the
machine would dispense it, add the niceties, stir it and then
serve it to you.
They used fluidics for missle guidance systems before
electronics became rugged enough, and in industries where having
electricity around is not a good idea (wet, explosive
Some of the equipment produced in the pre-electronic age are
truly works of art. A lot of machine tools were even hand
finished with a tool similar to a flat graver that left a
beautiful pattern. It certainly reflected the pride in
craftsmanship that you only see in limited areas now.
Island Gem and Rock