Hydraulic Analog Computer From 1949

mbone writes "In the New York Times, there is an interesting story about a hydraulic analog computer from 1949 used to model the feedback loops in the economy. According to the article, 'copies of the 'Moniac,' as it became known in the United States, were built and sold to Harvard, Cambridge, Oxford, Ford Motor Company and the Central Bank of Guatemala, among others.' There is a cool video of the computer in operation at Cambridge University. I remember that the Instrumentation Lab at MIT still had an analog computer in its computer center in the mid-1970s. Even then, it seemed archaic, and now this form of computation is largely forgotten. With 14 machines built, it must have been one of the more successful analog computers — a supercomputer of its day. Of course, you have to wonder if it could have been used to predict our current economic difficulties."

Comments

Explosives factories

[flyingfsck]

Some explosives factories still use hydraulics, steam or vacuum for process control. Although it tends to be digital now, with valves used as flip-flops.

Re:Explosives factories

[Thanshin]

Some explosives factories still use hydraulics, steam or vacuum for process control. Although it tends to be digital now, with valves used as flip-flops.

Furthermore, the factory itself can be considered as a digital information storage system.

The problem is returning to the current state after it flips to the other one.

Re:Explosives factories

[Keruo]

Upgrade properly to what? Hydraulics is the most accurate way to control movement.
If your application needs force with direction and accuracy, then your only real choice is to use hydraulics.

Don't confuse modern hydraulic systems with something that just has few handvalves.
Almost every system we deliver these days comes equipped with computer controlled digital valves which you can use to control pressures at 0.01 scale from 0 to 500+ bar(depending on customer specs naturally), and can be integrated into factory networks seamlessly.

[disclaimer, I have bias on this subject since I work at one of the largest suppliers of hydraulic systems in the world]

Re:Explosives factories

[K. S. Kyosuke]

Don't be shy to say it, a factory is a 1-bit PROM. Perhaps one day, a socially challenged but otherwise very friendly hacker will try to become immortal by writing "HELLO WORLD" into such memory, but no one will understand him, as usual. :-(

Re:Explosives factories

[petermgreen]

Indeed, when it comes to anything safety crtical KISS is a good principle to follow as it will make it much easier to ensure safety.

Re:Explosives factories

[Prune]

BS. Piezo systems are immensely more accurate--they're used for atomic force microscopes, for example. Of course, the range of motion is very limited, but your claim was _unqualified_ -- you wrote "the most accurate way to control movement". Make outrageous claims--get shot down! You should have known better, considering you're not new around here.

Re:Explosives factories

[Sen.NullProcPntr]

There is what could be described as a hydraulic computer that people use everyday;
The automatic transmission. Granted it has a fixed program but the early ones did use nothing but transmission fluid.

Computers can't model macroeconomics

[MSTCrow5429]

There is a serious flaw in thinking that computers can accurately model macroeconomics, or predict systematic collapses, any better than commonsense and basic logic can. It is a given that if you massively inflate the monetary supply, you will create a false sense of wealth and a false understanding of risk, and people will malinvest in sectors that they otherwise would have spent far less resources on, or none at all. This is an unsustainable artificially created bubble, and all bubbles burst. Many people saw this coming years, even decades ago, and didn't have supercomputers. People understood this scenario centuries ago, before computers even existed. Using computers as a crutch to make up for a lack of understanding of basic economics is an aggravating factor in the current scenario, not the solution.

Re:Computers can't model macroeconomics

[Anonymous Coward]

"What the hell can go wrong with lending $500,000 for a house to someone who's salary is only $20,000 per year?" - Brainless Banks

Re:Computers can't model macroeconomics

[caffeinemessiah]

There is a serious flaw in thinking that computers can accurately model macroeconomics, or predict systematic collapses, any better than commonsense and basic logic can

It might not be an accurate descriptive model (one that describes reality), but discriminative models are very useful -- not to predict systematic collapses, but to discriminate irrational behavior. Computers step in when your response time has to beat efficient markets. You could be a common sense and logic genius, but you can only apply those rules and react in so much time, and computers will always beat you for speed at applying your own rules. So it's a different kind of crutch, and just like a crutch, it can help you walk better, not walk for you.

I might have digressed from TFA, but this is /.

Re:Computers can't model macroeconomics

[CorporateSuit]

There is a serious flaw in thinking that computers can accurately model macroeconomics, or predict systematic collapses, any better than commonsense and basic logic can. It is a given that if you massively inflate the monetary supply, you will create a false sense of wealth and a false understanding of risk, and people will malinvest in sectors that they otherwise would have spent far less resources on, or none at all. This is an unsustainable artificially created bubble, and all bubbles burst. Many people saw this coming years, even decades ago, and didn't have supercomputers. People understood this scenario centuries ago, before computers even existed. Using computers as a crutch to make up for a lack of understanding of basic economics is an aggravating factor in the current scenario, not the solution.

Yeah, but if I can program a fly on the wall to recognize speech on the NYSE trading floor, and whenever it hears the words "The payoff is greater than the risk. Even the big guys are doing it like crazy. What's the worst that could happen?" then it sets off an alarm and shoots every Fortune 1000 controller in the face with a lethal stream of sulphuric acid... not only could I predict these things over a year before they happen, but after the two or three are predicted, I'm sure it would be at least 20 years before anything like this happens again... in the NYSE.

Re:Computers can't model macroeconomics

[vertinox]

There is a serious flaw in thinking that computers can accurately model macroeconomics, or predict systematic collapses, any better than commonsense and basic logic can.

Are you saying that human irrationality is defined by something other than the laws of physics, genetics, and chemistry?

If we are to believe that the universe does have a set of laws applied to it, then by understanding those rules can lead to models that will predict otherwise seemly irrational universe.

You just have to have the right model and a computer powerful enough to compute all the date required to get something use.

And you have to sometimes build something as big as the LHC to figure what model you should use.

To assume that this cannot assumes that universe does not have rational rules and is ruled by something else like a supernatural force.

Like you know... Like a Flying Spaghetti Monster?

Re:Computers can't model macroeconomics

[fiannaFailMan]

Spot on. I saw this mechanical computer on TV years ago, they were talking about how it was a noble attempt to model the economy but it's just too complicated an organism to be modelled by any means, to say nothing of a mechanical device. Sometimes the economy reacts differently when you poke it the same way depending on a myriad of other factors.

Another example is traffic. Some people assume that traffic can be modelled like water in pipes. "Road is congested? Make it wider and the congestion will ease." What they don't realise is that motorists are more intelligent than water particles. They can be aware of a widening of the pipes/roads and choose to go into a system at a certain point at a certain time to take advantage of the widened road, with the net result of a road that's just as congested at 4 lanes wide as it was at 3 lanes wide. There's also the matter of being able to move one's home to a different location along the road to avoid congestion. Others follow suit, and the congestion is back to where it was. Want to model that using water in pipes? Good luck!

Re:Computers can't model macroeconomics

[Trepidity]

I think it's not so much that it can't in theory be modeled, as that in practice it's extremely hard---much harder than modeling the weather, which we can barely do accurately out to 5 days. There's somewhat of a gap in expectations when you go from high-level qualitative descriptions of phenomena, like hurricane experts discussing trends in intensity and formation basins, to an implemented, detailed computational model that purports to simulate what "really" happens. The 2nd one usually diverges extremely quickly from what actually does happen, because these sorts of nonlinear systems are very sensitive to slight errors in the model or its initial conditions.

That's fine, as long as people understand its use and limitations; but there's a tendency, especially among the only-sort-of-technical folks who are involved in a lot of areas of business and economic policy, to trust these computer models as more than they are, as if the fact that a "computer simulation" told you it makes it some sort of neutral third-party truth that represents the state-of-the-art in guessing what will happen.

Re:Computers can't model macroeconomics

[fastest fascist]

It doesn't take a computer to predict what happens. You get a boom, people spend money, they overspend, you get a crash. Repeat. The details vary, but the basic pattern seems pretty clear.

Re:Computers can't model macroeconomics

[OwnedByTwoCats]

There are some fundamental limits to what models can predict. If a model demonstrates extreme sensitivity to initial conditions, then any deviation between actual and measured initial conditions will cause the output of the model to deviate from actual at an exponential rate.

Re:Computers can't model macroeconomics

[TheRaven64]

Modelling the economy is more difficult than most other modelling tasks because everyone is trying to do it. Every single actor in the system has their own model, of varying quality, which governs how they interact with it. When you build a better model of the economy, you have an advantage over the other players and so can make more money, which alters the economy. An accurate model which no one acts on is possible, but an accurate and useful model needs to be sufficiently complex to model itself and all of the other players. Or, to put it another way, needs to be more complex than itself. That's not to say that you can't build a partially-accurate and still useful model, of course.

Re:Computers can't model macroeconomics

[wjwlsn]

Your post reminds me of a quote from Gordon Box that I often relate to new trainees: "All models are wrong, but some are useful."

I don't think this modeling difficulty is unique to economics. (You didn't state or imply that it was... I just wanted an excuse to quote Gordon Box.)

I like your characterization of the problem though. It applies to pretty much any complex system.

Re:Computers can't model macroeconomics

[Tokolosh]

All you need is the Micawber Principle:

"Annual income twenty pounds, annual expenditure nineteen pounds nineteen and six, result happiness. Annual income twenty pounds, annual expenditure twenty pounds ought and six, result misery."

From David Copperfield, by Charles Dickens

Re:Computers can't model macroeconomics

[zindorsky]

What they don't realise is that motorists are more intelligent than water particles.

Says you.

Re:Computers can't model macroeconomics

[petermgreen]

If we are to believe that the universe does have a set of laws applied to it, then by understanding those rules can lead to models that will predict otherwise seemly irrational universe.
It is not feasible to make a perfect simulation of the universe since that it would require a computer more complex than the universe (and therefore unable to exist in our universe) to run and require information that the heisenberg uncertainty principle makes impossible to obtain as an initial state. Even if we could we would have to deal with quantum effects which as far as we can tell so far seem to be random.

So instead of a perfect simulation we have to settle for models based on approximations of reality and imperfect initial conditions. Combine error buildup from the approximations in the model with a chaotic system and you will find that beyond a certain distance out it is not possible to make meaningfull predictions

To assume that this cannot assumes that universe does not have rational rules and is ruled by something else like a supernatural force.
or just good old randomness.

Re:Computers can't model macroeconomics

[JesseMcDonald]

It's worse than that, actually. Weather prediction is at least based on physical processes, which, allowing for some minor concessions to quantum mechanics, are based on fundamental particles which follow deterministic rules. Given all the initial conditions and sufficient computing power you could accurately simulate what the weather will be at any point in the future. Moreover, you can use simulations to predict how that future weather will change in response to deliberate artificial influences; weather doesn't have goals of its own, and won't actively resist attempts to control it.

Economics isn't like that. The "fundamental particle" of economics is people, and people are adaptive. Under many conditions is it possible to predict how they will behave--assuming rational self-interest (i.e. sanity) and decent psychological models of their personal value scales--but all that breaks down when someone attempts to use the models to control the outcome. At that point you have a competition between the people being studied, who seek to achieve their original goals and thwart any attempt at outside control, and those seeking to do the controlling. As with any long-running competition between creative individuals, the outcome is impossible to predict with any degree of accuracy.

Re:Computers can't model macroeconomics

[gilroy]

Some people assume that traffic can be modelled like water in pipes. "Road is congested? Make it wider and the congestion will ease." What they don't realise is that motorists are more intelligent than water particles.

Also, when you treat traffic as a compressible fluid, you get 20-car pile-ups, because cars aren't compressible... or at least, they're not uncompressible afterwards...

Re:Computers can't model macroeconomics

[JesseMcDonald]

I never said humans were random. I also wasn't assuming that humans always pick their goals rationally. "Rational self-interest" doesn't mean that humans are completely rational, but rather that given subjective (and possibly irrational) goals, and a possibly inaccurate and certainly incomplete subset of the relevant knowledge, humans will tend to act in ways which appear likely to them to bring them closer to their goals. Anything else would be, as I said, the essence of insanity.

I acknowledge that crowd behavior can be more predictable than individual behavior. I think you'll find, however, that even crowds are difficult to control deterministically over the long term, in part due to the ways in which individual contributors can influence the result entirely out of proportion to their apparent power and in part due to the effects of creative adaptation, which grow more pronounced over time. The system is far from random, but it is chaotic.

Re:Computers can't model macroeconomics

[Q-Cat5]

There's a difference between mapping rules in a general fashion, and applying them to actual situations. Invariably, reality always has elements that differ from the model, and thereby make it inaccurate. This is why reductionism doesn't generally map back accurately to the big picture. Understanding a component is different from understanding how the component integrates into the whole, and how other components within the whole interact with, and alter, the component.

Human behavior is very nearly impossible to accurately model at the individual level. You hear "I never would have expected him to do that" when people speak about their next door neighbors who go on homicidal rampages. Husbands or wives are shocked when the spouse that they've lived with for years or decades has an affair, buys a sports car, or has a second cup of coffee after dinner. Even crowd dynamics can be altered by incredibly subtle, and unpredictable, circumstances. (Someone in a crowded line says "He's got hairy wrists", someone else hears "He's a terrorist", and soon 8 are trampled to death in the ensuing panic.)

Then, add people deliberately gaming the system into the equation. (i.e. someone else wants to steer the crowd in a different direction than your model would normally predict, perhaps even using your model to predict the best way to disrupt it.)

Raw computing power just can't compensate for all the variables. At some point of hyper-precision, they become recursive anyway, and Gödel gets to have posthumous a laugh at your expense.

Re:Computers can't model macroeconomics

[MSTCrow5429]

This is inaccurate. I disagree with the chronic and consistent misuse of computer modeling, such as within economics or climate modeling, where the variables are assumed to exist without any rational basis, empirical history is disregarded as being a nuisance to the desired results, and past mistakes in the model are ignored or covered up. I have no problems with computer modeling in designing, say, a car, airplane, or bridge.

Perhaps it used the wrong working fluid

[OolimPhon]

It might have been more successful if they had used beer instead of water...

Hot and cold running money!

[thewiz]

Wow! Great article about it in Wikipedia. Loved the picture that showed the two faucets on the side.

Re:Hot and cold running money!

[langelgjm]

Yeah, the WP article is much more informative than the video. The guy in the video spends the first minute kind of standing there saying "now what I'm going to do..." without actually doing anything. The next two and half minutes aren't much better.

Re:Hot and cold running money!

[adolf]

And then the video just sort of ends, without the computer having, um, computed anything. The whole thing is about as entertaining and instructive as watching the skimmer on my swimming pool (except the skimmer might actually be more interesting).

Does anyone have a better (or simply more-complete) moving-pictures demonstration of this remarkable machine?

Gack... troll in summary... must resist...

[Red Flayer]

Dammit. Couldn't resist.

Of course, you have to wonder if it could have been used to predict our current economic difficulties.

No, you don't have to wonder that. The current economic difficulties were easily predicted by many.

The problem was that the people with any kind of ability to stop the conditions that led to the current situation were those who profited most from those conditions. Not a good recipe for prevention.

Re:Gack... troll in summary... must resist...

[Red Flayer]

Sorry, I wasn't referring to the mortgage brokers. The stood to gain some, but the people who stood to gain the most were the people dealing in securitized mortgage derivatives. These are the people with the $50 mil bonuses. As long as they weren't left holding the bag when it came tumbling down (and they weren't -- their employers were), then their best choice was to keep the cash flowing.

As for your friend, there's more there than meets the eye, and definitely more than what you stated.. Almost all lenders offered both conforming and non-conforming loans, with different fees, rates, etc. I spoke with several lenders who only offered conforming loans (ended up going with one of them), and they weren't sued out of business. Requiring substantiated income is a prerequisite for conforming loans.

Congress dropped the ball on this one. They wanted everyone to be able to buy a house, whether or not they could pay for it.

I think if you do a little deeper research you'll find that that myth has been debunked. I'm not sure how well read-up you are on the issue, from your post it seems like you have some understanding, but are missing important pieces... I don't mean to be mean or condescending, please don't take it the wrong way... but there were a lot of deregulatory actions that affected the mess. Effective repeal of Glass-Steagal, etc.

I don;t think Congress wanted everyone to be able to buy a home... they wanted (1) a place where the bubble money from the dot-com boom could be put to delay the burst and (2) to make their buddies in the financial industry happy.

Wierd! Just read Terry Pratchett's

[bareman]

I just finished with Terry Pratchett's "Making Money". I think I'm having a flashback now.

Blowing a circuit - with air

[diodeus]

In college I built a divide-by-eight counter in pneumatics. One reciprocating cylinder was the "clock" signal, the rest was a bunch of pneumatic shuttle valves. Problems arose because I kept needing to increase the air pressure to move some of the switches because they were spring-loaded. The air hoses started to pop off their fasteners so it took a lot longer to get the assembly working that I had anticipated (talk about blowing a circuit). It did manage to get me an exemption from the rest of the labs though.

Re:Blowing a circuit - with air

[BrokenHalo]

In college I built a divide-by-eight counter in pneumatics.

It would be more impressive if you could build a divide-by-zero counter. :-D

(Almost) seriously though, this contraption rocks! A few more gear-wheels and this just might make a perfect steampunk computer... ;-)

A funnel can model "current economic difficulties"

[shadowofwind]

If lots of people are extracting money from the system and not contributing real wealth, then there will be problems. Money has complicated dynamics, but its not magic. People who make a living shuffling numbers around in spreadsheets are providing a useful service that makes the system more efficient. But only up to a point. Few people believe greed is a vice anymore, hence certain results follow.

Used in fighter planes

[Maximum Prophet]

Hydraulic computers are used in some military aircraft because they are very reliable and can withstand EMP.

Re:Used in fighter planes

[Lord Ender]

... but not an ice storm.

Memory Leak

[SubjectiveObjection]

"Johnny, there's another damn memory leak! Bring the bucket!"

Predict the economic trouble today?

[modmans2ndcoming]

Probably not, but Byron Dorgon Predicted this trouble in 1995 when teh derivatives markets starte to get noticed and again in 1998 when the "securities modernization act" was passed, deregulating the banks, insurance companies and investments firms.

Re:Predict the economic trouble today?

[inviolet]

Probably not, but Byron Dorgon Predicted this trouble in 1995 when teh derivatives markets starte to get noticed and again in 1998 when the "securities modernization act" was passed, deregulating the banks, insurance companies and investments firms.

As we say in Economics circles: "Yes, the man is a genius: he predicted 9 of the last 3 recessions!"

If we would have stayed with this technology...

[sootman]

... the Internet truly would be a series of tubes.

Also, little known fact: Gordon Moore's father was a mechanical engineer who predicted that the size of hydraulic valves would shrink 50% every 18 months.

pneumatic computers exist too

[OrangeTide]

In class I built a half-adder and a full-adder and could do 2 bit addition with it. subtraction too if I interpret input and output as 2s complement numbers. I ran out of parts in my kit to make it bigger. but with enough parts you could do pretty much anything, as long as you don't mind the slowness and noise and possibly a tremendous amount of power.

hydraulics have the advantage that you can apply a great deal of force through them precisely. which is useful when you have many layers of "logic gates" that you have to drive by pushing a fluid through some tubes. with pneumatics I could have quickly ran into an issue if I made a ripple counter for example where the amount of pressure necessary to switch the furthest most element might exceed the abilities of my pump.

Re:ya gotta be kidding!

[Brett Buck]

1998, you mean. There was a reason they had all those banking rules developed over centuries, You can't just wipe them out with a stroke of a pen, and expect no consequences.

        Brett

Hydraulic Computers

[thethibs]

Which gave rise to one of the oldest computer jokes: "If it doesn't work, piss on it."

Trend setting

[DrugCheese]

This was water cooled before water cooling was cool

Not quite

[DerekLyons]

With 14 machines built, it must have been one of the more successful analog computers

 
In the early 80's the USN had over 30 analog computers driving various submarine simulators. Heck, each of the original '41 SSBN's had an analog computer driving the hovering system. Then there was the 100+ analog installations of the CONALOG system.
 
Etc... Etc...

Re:Not quite

[Nimey]

Also the famous Norden Bombsight, the most accurate in the world at the time, was an analog computer.

Re:Wierd! Just read Terry Pratchett's

[TheRaven64]

And this is why you should always read the author's note at the end, where he mentions all of the things that he based inventions in the book on. You also get fun things like, in the end of Nation, an explanation of thinking, followed by 'do try this at home'

Yep

[madnis]

Shows that our economy is down the drain.

Re:Discworld anyone!

[SteveAstro]

You'll actually see TP give due acknowledgement to the Phillips Economic computer, Moniac, at the front of the book.

As a result of reading Making Money, I tracked down the prototype, which is in the foyer of the school of management at Leeds University in the UK, and now have the job of rebuilding Phillips very first machine.

Steve

Other Great Analogue Computers

[Nom du Keyboard]

What about The Great Brass Brain? An analogue computer for computing tide tables that when replaced by a CDC 6600 super (for its time) computer, the 6600 couldn't perform all of the tricks (i.e. pause at each low/high tide moment or produce a continuous) graph of the machine it replaced? There's some great, mostly lost, history out there.

A five year old with an abacus and 20 minutes

[nedlohs]

Could predict todays our current economic difficulties and spend 18 minutes playing with the abacus.

Another resource too...

[DrYak]

The Annotated Pratchett File has also interesting resources to help grasp to more obscure jokes.

Modern Replacement

[Nom du Keyboard]

Seems to me that this could be replaced today with an Excel spreadsheet - and no I'm not being facetious.

I Once Had a Toy...

[Nom du Keyboard]

I once had a wonderful, yet frustrating, toy whose name I can't remember any longer that was kind of a hydraulic Erector Set. It came with battery-powered pumps, clear plastic tubing, splitting/combining Y and T connectors, valves, tanks, items that filled and then tipped out, a board and supports to arrange everything, and even coloring tablets (messy) to allow blending different streams -- just add water. The frustration came from the poor level of construction that resulted in it not being all that durable and the pumps not seeming to work as long or as well as I felt they should. And when you used it you pretty much ended up with water, and staining colors when you added them, in a mess all around. Even so it was one of the great fun toys (along with Lincoln Logs, Tinker Toys, Erector Sets, and Flexigons) that I would happily play with now if I could find them again. No, we weren't a Leggo family.

obvious...

[FalloP]

now i truly understand a buffer overflow, and the implications of a memory leak are clear.

biennale

[spud603]

I saw one of these in operation at the Venice Biennale in 2003. It was really remarkable to watch, but then I was thinking of it as more of an art project pointing out the absurd nature of economic forecasting than a serious research tool.

If these ran the internetz. . .

[kimvette]

If these did run teh internetz, then the Internet really WOULD be a series of tubes! :D

Analog computing has its place

[mcrbids]

Often, digital computing is clumsy, awkward, and overly precise.

A good example of this is in Aviation. Pilots are still trained to use the E6B Flight computer which is really a glorified slide rule.

When you are estimating fuel consumption, and figure you'll probably use about 11.5 GPH for 3 1/3 hours, it's not important to know any more accuracy than perhaps to a gallon or so, since reality will always be a bit different than your calculations, anyway. You don't need to be exactly precise on your degrees of heading, and when you are computing weight & balance, it's stupid to calculate your moment to the 4th decimal place.

Knowing how to use an E6B, you can get calculations in a second or two with a single hand that are "good enough" - and that's important when you're flying an airplane in turbulence while trying to stay on top of busy ATC calls in a heavily trafficked area. You can't even enter the first of 3 or 4 digits into a digital calculator in that time, and you'd have to use two hands. (Frequently, when flying, your hands are both occupied and you're steering with just your feet)

Digital isn't always better.

Biased? hardly

[Runaway1956]

I work with and service a lot of hydraulic machines. Generations of them, in fact. The pilot valves and such really haven't changed much in 50 years, as they are a simple device - but the CONTROLLERS are simply awesome. We use mostly David Bradley stuff, but there are plenty of Japanese, Chinese, and Korean valves and controllers in the plant. Amazing how accurate they can be when remotely controlled by a computer. Hydraulically powered computer can be sent 30 feet away from you, and come back, kiss your forehead, or a baby's cheek, and sent out again. It will repeat ad nauseum, and NEVER strike you hard.

Air? I would never trust air powered mechanisms to touch a baby, and simple electric motors can scare me too. Don't even dream of doing it with some kind of gasoline powered machine. Hydraulics are more reliable than anything I can think of.

Cool video

[YourExperiment]

There is a cool video of the computer in operation at Cambridge University.

No, there really isn't. The video consists of 3 minutes and 38 seconds of a guy explaining how he's not an economist and doesn't really understand this stuff, and clearing his throat an awful lot. Meanwhile, he proceeds to explain how he's shut off or removed most of the parts of the machine, and intends to only demonstrate a little bit of it. Just as he's about to begin the demonstration, the video ends.

Fluidic Systems

[TheSync]

I'm a fan of Fluidics, which can create analog or digital devices based on fluid flow.

See this powerpoint for a great history of fluidics.

Analog is slick

[g01d4]

I took an (electrical) analog computing course in the mid-70s. Best (only?) way to solve differential equations in real time till clock speeds caught up. LIke music on vinyl vs. 1KHz sampling. Optical ain't dead - how about a 2D FFT at the speed of light?

Obligatory Ada Lovelace comic

[lennier]

Featuring an Economic Model inspired by MONIAC:

http://sydneypadua.com/2dgoggles/lovelace-and-babbage-vs-the-economy/

Crunchly's hydraulic computer

[dido]

There's a whole series in the Crunchly cartoons by Guy L. Steele, such as this one where he buys a hydraulic computer of sorts...

horrible video

[Teque5]

'cool video' is really a misnomer - the guy doesn't explain anything and nothing happens. 3:28 of my life i will never get back.