
Vladimir Lukyanov's hydraulic computer - bogidon
https://pruned.blogspot.com/2012/01/gardens-as-crypto-water-computers.html
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contingencies
Image @
[http://www.digitaljournal.com/img/7/7/5/0/6/8/i/1/3/3/o/wate...](http://www.digitaljournal.com/img/7/7/5/0/6/8/i/1/3/3/o/water_computer.jpg)

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toolslive
In the 1980s people in chemistry labs that needed to find the area beneath a
curve used to print/plot the curve, cut out the area and weigh it. This worked
quite well as they had accurate scales.

~~~
gugagore
Ha! Very interesting. And the density of paper was uniform enough? Or maybe
they used a different material?

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toolslive
I'm not sure if they ever did a scientific study on this, but you can choose
your accuracy by playing with the scale of the plot.

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lb1lf
In a related vein, Ars Technica writer Sean Gallagher did a fantastic story on
the US Navy's analog fire guidance computers a few years ago:

[https://arstechnica.com/information-
technology/2014/03/gears...](https://arstechnica.com/information-
technology/2014/03/gears-of-war-when-mechanical-analog-computers-ruled-the-
waves/)

The instruction videos alone are worth the visit. Geekery of the first order.

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B1FF_PSUVM
Incidentally, these were the computers in the early Heinlein books.

I was mulling the comment here a few days ago pointing out Heinlein's
prescient depiction of networked computers, and thinking that the hard part
would be having mechanical computers pick up the phone and sending
electromagnetic pulses down the line. Perhaps pecking at telegraph keys ...

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DonHopkins
Ash the Android in Alien used a water based computer. Or maybe that was milk.
It looks like he might have been had problems solving non-homogeneous
differential equations, because the cream would rise to the top.

[https://www.youtube.com/watch?v=VA8jv1M6Y2g](https://www.youtube.com/watch?v=VA8jv1M6Y2g)

~~~
SmellyGeekBoy
I always thought it was some kind of hydraulic fluid but I prefer your
explanation. ;)

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wpietri
I know of two excellent examples of this. One is an entertaining modern
attempt to recreate economic models with a fluid computer:
[https://vimeo.com/131690448](https://vimeo.com/131690448)

The other is the fucking fantastic Bay Model, a 1:1000 physical model of the
San Francisco Bay:
[https://en.wikipedia.org/wiki/U.S._Army_Corps_of_Engineers_B...](https://en.wikipedia.org/wiki/U.S._Army_Corps_of_Engineers_Bay_Model)

It was built in the 1950s to study the effects of various plans, including one
proposal to divert all incoming rivers to "productive" use. It was eventually
made obsolete by computer simulation, but it's still there. I bring a lot of
my nerdy out-of-town visitors there; it's amazing to walk around on a 2-acre
simulation.

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JKCalhoun
Yes, first link is based on the MONIAC:
[https://en.wikipedia.org/wiki/MONIAC](https://en.wikipedia.org/wiki/MONIAC)

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obeattie
There's a little more info in this (somewhat wonderful) article:
[https://pruned.blogspot.com/2012/01/gardens-as-crypto-
water-...](https://pruned.blogspot.com/2012/01/gardens-as-crypto-water-
computers.html)

~~~
dang
OK, we've changed to that from
[https://en.wikipedia.org/wiki/Water_integrator](https://en.wikipedia.org/wiki/Water_integrator).
Thanks!

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comboy
> he water level in various chambers (with precision to fractions of a
> millimeter) represented stored numbers

I wonder how did they deal with thermal expansion. Maybe instead of using
water at room temp they heated it to something higher and then a thermostat
took care of it? But it still would be very hard to distribute heat evenly.

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VLM
Thermodynamics lab tech was pretty advanced by that time.

The part that reads bogus to me is the fractions of a mm, water meniscus is
sensitive to contamination and diameter, its "always" been easier to measure
liquid masses to higher sig figs than to measure liquid volumes, I suspect the
journalist filter turned mg into mm or the precision scale produced repeatable
results equivalent to fractions of a mm in the container. The only solution I
can come up with that would work in that era would be something weirdly
optical involving mirrors and multiple floats.

I vaguely remember a quarter century ago in a chemistry lab placing a beaker
of distilled room temp water in a very nice precision scale as a demonstration
while the instructor had us calculate how long it would take the inch or so of
water to evaporate based on the slowly decreasing mass, and the result during
a dry winter was somewhere around a month. The room must have been sealed and
100% humidity because small fractions of a mm in height would represent in a
very hand wavy way around a minute of evaporation if represented as time in
normal winter lab air. I also wonder how volume of water changes as CO2 is
absorbed or emitted by the water, even the smallest gas bubble could mess up
fraction of a mm measurements.

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DonHopkins
If you squinted, you might consider the U.S. Army Corps of Engineers Bay Model
a giant low tech special purpose water computer.

[https://en.wikipedia.org/wiki/U.S._Army_Corps_of_Engineers_B...](https://en.wikipedia.org/wiki/U.S._Army_Corps_of_Engineers_Bay_Model)

>The U.S. Army Corps of Engineers Bay Model is a working hydraulic scale model
of the San Francisco Bay and Sacramento-San Joaquin River Delta System. While
the Bay Model is still operational, it is no longer used for scientific
research but is instead open to the public alongside educational exhibits
about Bay hydrology. The model is located in the Bay Model Visitor Center at
2100 Bridgeway Blvd. in Sausalito, California.

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therein
I believe now one could use microfluidics to leverage similar principles but
miniaturize it almost into the size of a chip.

Here is an interesting demo:

[https://youtu.be/7z8I7awRYY4?t=114](https://youtu.be/7z8I7awRYY4?t=114)

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mr_tyzic
Hydraulic integrator would be a better translation.

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ilikehurdles
Fix it!

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cdepman
Reminds me of the stone/water brains of the Quatzoli people in Ken Liu’s short
story, "The Bookmaking Habits of Select Species".

[http://www.lightspeedmagazine.com/fiction/the-bookmaking-
hab...](http://www.lightspeedmagazine.com/fiction/the-bookmaking-habits-of-
select-species/)

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yesenadam
I'm not sure how different this is to the ball integrator?[0] or Vannevar
Bush's differential analyser?[1] The water computer article says partial
differentiator, then integrator, it's unclear.

[0] [https://en.wikipedia.org/wiki/Ball-and-
disk_integrator](https://en.wikipedia.org/wiki/Ball-and-disk_integrator)

[1]
[https://en.wikipedia.org/wiki/Differential_analyser](https://en.wikipedia.org/wiki/Differential_analyser)

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kabanossen
Pretty cool. Reminds me of MYST

[http://myst5.com/images/mystgallery/channel_2.jpg](http://myst5.com/images/mystgallery/channel_2.jpg)
[https://lparchive.org/Myst/Update%2015/3-1103_Switchflip.gif](https://lparchive.org/Myst/Update%2015/3-1103_Switchflip.gif)

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hliyan
This reminds me of "rod logic" computers:
[https://hackaday.com/2015/10/19/rod-logic-and-graphene-
elusi...](https://hackaday.com/2015/10/19/rod-logic-and-graphene-elusive-
molecule-scale-computers/)

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bencollier49
This rather reminds me of the economic model in Terry Pratchett's "Making
Money".

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jedimastert
Fun fact, the device you're referring to was actually based on a different
real-life water-based computer, the MONIAC[1]. It used basins of water, pipes,
and adjustable flow regulators as a physical metaphor for the movement of
money in macro-economics. I'm personally a really big fan, and I've need
meaning to work up a simulation for quite some time now.

[1]:
[https://en.wikipedia.org/wiki/MONIAC](https://en.wikipedia.org/wiki/MONIAC)

~~~
JKCalhoun
Awesome. I imagine a Water Computer Construction Set that allows you to
"plumb" a computer program.

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agumonkey
Similarly there was a story about a ~computer based on water surface tension
to encode complex equations and let the physics approximate a solution in
parallel. Can't find the name though.

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JKCalhoun
Found an online link to one of the articles Dewdney wrote for Scientific
American about "analog computers" (this is the second article, there was one a
year earlier):

[http://www.softouch.on.ca/kb/data/Scan-130202-0003.pdf](http://www.softouch.on.ca/kb/data/Scan-130202-0003.pdf)

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wintorez
That sounds like something out of the Dune universe.

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TomMarius
I think that would be forbidden* - a machine doesn't have to use
semiconductors or even electrical current to be a machine.

* "Thou shalt not make a machine in the likeness of a human mind."

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davestephens
Wonder if they had cross-core security vulnerabilities?

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Arkight
Even better, is remote hacking of analog computer even possible?

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whatshisface
It's not connected to anything, so probably not. However back when we used
purpose-built electromechanical switching systems for telephones, people
exploited them[0].

[0][https://en.m.wikipedia.org/wiki/Phreaking](https://en.m.wikipedia.org/wiki/Phreaking)

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DonHopkins
If the phone system used water instead of electricity for in-band signaling,
would phone phreaks have to inject blue fluid into the pipes to exploit them?

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whatshisface
If water pipes were used for signalling, it would probably be as acoustic
conduits (analogous to wires, which are electromagnetic wave conduits). You
would exploit them in just about the same way as the electromechanical systems
were.

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SmellyGeekBoy
Gives a whole new meaning to the term "wiretap".

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msravi
More details

[https://pruned.blogspot.com/2012/01/gardens-as-crypto-
water-...](https://pruned.blogspot.com/2012/01/gardens-as-crypto-water-
computers.html?m=1)

~~~
dang
We've changed to that from
[https://en.wikipedia.org/wiki/Water_integrator](https://en.wikipedia.org/wiki/Water_integrator).

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evv
Talk about floating point precision!

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yk
"Can someone mop up the memory leak?"

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ykampittaja
Reminds me of a discussion I heard:

Customer: the phone complains memory is full. Rep: ok there is probably a
memory leak. Customer: no, it cannot be leaking since it is full!

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don_gecko
If I recall correctly, the world3 model which the authors of 'the limits to
growth' used also utilized fluids to simulate the increasing, or diminishing
influence of different factors on our ecosystem.

