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Karlův most - Stavba pilíře a klenebního pole ve 14. století · Youtube · 960 HN points · 4 HN comments
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3D grafika a postprodukce: Tomáš Musílek

Odborná spolupráce: Ing. Arch. Ondřej Šefců
Grafická spolupráce: Mgr. Zdeněk Mazač

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Digitální model "Karlův most - stavba pilíře a klenebního pole ve 14. století" byl vytvořen pro projekt virtuální výstavy Praha doby Karla IV. Projekt je podporovaný MK ČR jako součást Národních oslav 700. výročí narození císaře Karla IV. a je zařazen do programu Strategie AV21.
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I'm actually surprised that none of the proposals contain my idea of raising the water level.

Mostly copied from 5 minutes ago:

> Surround the boat, make a dam somehow and raise the water level.

Concrete is dry in 24-48 hours. Sand and wooden poles could be enough.

Some ideas on the how, could be found in this video, on how they created a bridge in the middle ages:

I'm pretty sure engineers could find better/faster solutions than what I'm proposing to raise the water level more quickly.

Edit: Omg, a record amount of downvotes for suggesting this: ;)

Thanks Arrath for mentioning sheet-pile coffer dams.

Edit 2: it seems that timer crib coffer dams are supported for 10-20 meters deep and diagrapragm or cellular cofferdams are used for more than 20 meters.

This is the most precise estimate that I could find on duration of construction for a 2100 foot ( 640 meter) cofferdam with a limited workforce ( 16 days! for probably a less sophisticated cofferdam)

So, while my suggestion is plausible to execute. It could take too long ( planning + execution).

I guess we'll find out if the current solution will work within the current time-frame, since they have a huge amount of dredging to do.

For that to work, the dam has to go all the way around the boat, all the way to the bottom of the canal, and create a water-tight (or close enough) seal. That's non-trivial. And then, once the boat is unstuck, then your dam is blocking the canal, and has to be removed, all the way to the bottom, or it becomes a hazard.
Did you see the video?

Going to the bottom of the canal is "only 24" m. The video I gave before shows some ideas on how to do it.

Quick thought: A skeleton where the bottom layer is filled with wooden poles ( to stick them firmly in the ground). The rest is a construction that is quicker to create.

The ground of the "canal" could be 3D mapped for precise measurements ( a company i know does this).

And you'd need some additional meters on top of this to raise the water level.

This comment gives me serious Dunning-Kruger vibes.
Could they just push a really big wave at it to temporarily raise the water level?
Sheet-pile coffer dams are a solved problem, but it would take a good amount of time to drive all the piles. Not to mention that removing them again afterwards is not a speedy process, either.
The canal is very wide, very long, and very deep. It would take an enormous amount of mass to accomplish what you propose, and an even bigger effort to clear the debris afterwards to ensure safe passage of other ships.
Depends if you can fill the outside with poles and the inside with sand.

You can suck up the sand ( if it's even required, since normal dredging could be done afterwards) before you destroy the construction again.

If it's surrounded by poles, then you just take them out again on the end.

The construction on land can be cleaned up afterwards.

The canal is a minimum of 80 feet deep and over 254 feet wide (a lot wider actually, 254ft is the max boat beam it can handle). It's a little bigger of an issue than dropping some telephone-pole sized rods into the canal.

It's one of the most highly trafficked canals in the world, I'm certain if the solution was this simple they would already be doing it.

Using traditional things ( eg. Cofferdams) for non-traditional uses ( raising water instead of lowering) aren't always considered by the same experts.

The problems that I heard of till now are logistics and duration ( since it also has to be removed). None mentioned the depth/length since it is doable and had been done ( cofferdams, but with more planning ofc)

It could have been more plausible if the problem was worse though.

> Using traditional things ( eg. Cofferdams) for non-traditional uses ( raising water instead of lowering) aren't always considered by the same experts.

True but I guarantee you that's not the case here. Any engineer who's familiar with canals will have coffer damns in the front of their mind, because that's exactly how locks work. And besides that, it is (forgive me), kinda obvious.

I promise you the people working on this have thoroughly explored the possibility of raising the water level, probably by more means than you or I can guess.

Sometimes, obvious things have to be said first before it becomes obvious.

I don't know if they'd raised the water with cofferdams before, i checked online and haven't seen an example ( didn't knew the term at first either). I also didn't see it proposed before or mentioned in any related articles.

It's possible that it was done in the past and is a known thing among experts, but i can't really know that, can I?

I guess if you’re this convinced that you have uniquely thought up and proved this idea the only thing left is to phone them up and let them know you’ve got a solution ready to go! There’s a phone number on their website.
Who said I'm convinced that i uniquely thought of that?

What's wrong with you? This isn't your first demeaning comment.

This is literally a place where people tend to discuss/propose things on and get feedback. HN can give a unique insight of commenters that ARE experts on the topic, even while the poster is not. Not many people here see issues with that.

I think you’re the one demeaning the engineers working on it to be honest - saying you’re surprised they aren’t considering your idea.

Likely so did everyone else downvoting you.

I also said that the engineers would know better than me in the same comment. I've never claimed to be an expert and I've made that pretty obvious from the start.

While my original comment could have been worded better, which I already admitted, your reactions aren't a work of art either.

Calling it delusional and patronizing, while both methods were deemed feasible afterwards, for example. Take your pick.

My intention was always to find out the variables surrounding it and how to make it work and I think most people probably realized that. ( the "badly" worded comment only received -2 fyi, it's just more than what I'm used too)

PS. Some people also disagreed with your perception and told you literally to relax a bit. If you really want to go down that road... ( Didn't I already mention something about your demeaning comments just now?)

@chrisseaton, here's what I think :

My first comment mentioned that you misinterpreted my words. Someone else disagreed with your perception. Someone else said to relax. I pointed out multiple times, that my original comment was badly worded.

Have you even considered the possibility that you misinterpreted the original comment, where you based your toxic reactions on?

Perhaps consider that the "proposals" I'm talking about in my original comment, ARE NOT what is currently being done now in the Suez Channel by the experts (eg. Dredging). Those aren't proposals, that's what currently is being done! But what has been suggested here on the different threads of HN.

I was genuinely eager to see alternative implementations of that concept ( raising water) proposed somewhere.

I copied my example of the other thread as a proposal ( = dams), which led me to the path of water based cofferdams and some other interesting google searches, thanks to comments here.

Now... Reread the original comment and the first sentence in particular ( )

Completely uninformed guess is that what they're doing is faster and cheaper, and the "get it unstuck enough" point will be reached sooner.

> Concrete is dry in 24-48 hours.

Sure, but building a dam around the entire ship? How much concrete are you going to need, and how long would it take to build? They're pumping sand and dredging right now, today.

Do people on Hacker News genuinely think they’re able to come up with tractable ideas that wouldn’t be considered by the actual experts working on the problem?

This person wants to build a damn, someone else wants to use helicopters... waiting for other patronising armchair engineers to weigh in with other reasons why the experts have it wrong.

Glad someone else said it... nothing like a bunch of software engineers assuming they're more qualified at major maritime salvage than actual experts.
Armchair engineers?



I never saw it that way.

I think most people suggesting helicopters (as an example) know they are probably not feasible but are curious as to why not.

> Patronizing?

Random person on internet confused about why professional engineers haven't taken note of the idea they just came up with. It's either patronising or delusional - take your pick.

You ought to relax a bit. You could, theoretically, just let some random people on a techy forum geek out about disasters and engineering. Since no one is listening to us except ourselves, exactly what do you hope your scolding will accompish?
Or just bored and seek dialogue?
Conclusion: Both aren't delusional and seem to be possible -

But hey, thanks for your valuable feedback.

Or perhaps the wording was off as their (my) reason to copy-paste most if it from something they wrote a minute before that on another and highly relevant thread.

Take your pick.

+ It does work: ^^ and without some downsides i read first ( eg. keeping the balance of the ship or putting additional stress on the structure of the ship)

Just interested in what the problems and potential solutions are on that scale.

But the parent comment was pretty gently put. I didn't read it as armchair criticism, but rather more wondering aloud. The idea of cofferdamming the ship is entirely feasible, and I too am curious about how it compares to other interventions in terms of time and effort.

> He said it works in theory.

> He didn't estimate timeline, but it would take longer than a weight/crane operation. If the situation was much worse (partial capsize, somehow deeper entrenched on the coast), this might be a more plausible option. With the containers in an accessible location, it should be faster to organize a weight redistribution campaign instead. Just thinking about the logistics of safely building and deconstructing the dam made his head spin a little bit.

Remember elon's cave sumbarine :D
"That would have worked if you hadn't stopped me!"

- Spengler in Ghostbusters

Wow, that's harsh.

If I'd explain it as using cofferdams ( temporarily structures) to raise the water instead of the traditional lowering. Is that better for you?

I'm 100% sure that using simple solutions to hard problems is not always thought off when something is not used in it's "traditional" sense.

Sometimes outsiders give another POV that could be actually useful. And sometimes it isn't.

No need to get rude for that... Perhaps try some constructive feedback on why it shouldn't work next time? :)

PS. Before you misinterpret my words again. I'm saying that the concept is simple ( raising the water level), not the execution of it. Since on this scale every solution is harder to execute.

Edit: It's already been confirmed by another poster that it should work in theory: ( with pro's and cons)

I'm not saying the entire canal. Surround the boat, make a dam somehow.

Concrete is dry in 24-48 hours. Sand and wooden poles could be enough.

Some ideas on the how, could be found in this video, on how they created a bridge in the middle ages:

I'm pretty sure engineers could find better/faster solutions than what I'm proposing.

Lot of heavy containers that aren’t being used at the moment.
The canal is 200 metres wide, 25ish metres deep. Gotta think in the cube, because now you're talking volume. I have zero idea what thickness you're going to need for your dam, but I'm going to spitball and say 10 metres at the top, and 30 metres at the bottom to get a slope like you'd see on something like the Hoover Dam.

This means you need to provide .. lets see, a trapezoidal cross section is 500 square metres.. 100,000 cubic metres of filler. Twice. And then you probably need to curve it to resist the pressure, so that's a bit of a lowball figure. You can't dam any less, because the ship is stuck sideways across the canal.

Using some old numbers for concrete pours in Ireland (2016 era) per cubic metre, that's 7.5 million Euro worth of concrete. Sure, you're not going to use pure concrete like that though - you'd probably start dropping massive boulders in first, and then try to cap/fill it.

Have a read of to get a feel for how long it takes to lay in that much material..

And then you have to dig it all back up to reopen the canal.

> Using some old numbers for concrete pours in Ireland (2016 era) per cubic metre, that's 7.5 million Euro worth of concrete.

A sister comment mentioned 400$ million per hour worth of trades being blocked by this, so the cost of this would probably recouped by the time the order is cleared.

>A sister comment mentioned 400$ million per hour worth of trades being blocked by this

but it's not $400M lost? If you ordered a $100 package from amazon and it got stuck in transit it's not a $100 loss.

Quite a lot of shipped goods have tight delivery schedules requirements.
There are fees associated with lateness.
Not all. But there are late fees, refunds, profits lost because your ship now has to travel a larger route and can therefore take fewer roubdtrips, increasing costs per roundtrip due to the longer route etc.. If we just assume a meager 1% actual loss, the concrete would be worth it in two hours. Even with the remaining expenses due to work, this should pay for itself rather quickly.
So clearly we just find some sand beavers.
160 km of protection against 2m. High waves to build something on unstable soil isn't exactly the same thing as this, is it.

They need some construction which they can add water faster than it escapes the container, to raise the water level.

If stacked water based cofferdams would be a solution ( idk depending on these requirements, current, ..), it could be done quickly if they have the bags ( multiple teams, multiple locations to start and filling the coffers with water as soon as possible). The budget to fix this fast is probably pretty high. A lot would depend on how much they need to raise the water for the pressure, so it wouldn't collapse. ( Fyi, i do think water based coffers would collapse, but perhaps sand ones can be placed in top on it for 1 meter).

Palm islands needed a construction that holds multiple years and isn't the same as the issue in the Suez canal.

Tu be honest, I'm just thinkering about the variables that could make this work, instead of dismissing it immediately.

Oct 16, 2020 · 959 points, 238 comments · submitted by BerislavLopac
Fun fact: Charles bridge (depicted in the video) was damaged during a flood in 1890. With the water level risen, broken down rafts were beating its arches and two of them fell apart, along with three pillars that were undermined by the water. During the reconstruction of the pillars, they decided to make them hollow (to cut on the weight) and you can actually go inside! It's not open to the public but there's a video that shows the inside of a pillar number 6 [0].


Normally I do not pay attention to ads but was curious to know - what was that Santa selling! And I can't speak a word of Czech.

1:26' into the video - Is that guy praying? Read there are statues of Saints on the bridge.

Found an image of 1872 flood -

The river was used for centuries for transporting wood.

> Normally I do not pay attention to ads but was curious to know - what was that Santa selling!

Haha, you mean the long bearded guy with a dog sitting next to him? That was a commercial for a search engine [0]. The premise of the commercial is that people come to this wise old man for advice and he seems to know everything, while in reality he just uses the search engine to look up the information.

> 1:26' into the video - Is that guy praying? Read there are statues of Saints on the bridge.

There's a lot of statues [1] but my first guess would be that the guy was simply begging for money. I could be wrong though.


[1] (the English version of the page doesn't have that many pictures)

I used to be tempted to think that our modern generations are extra smart because of the cool gadgets we have.

Seeing stuff like this, and reading ancient political / philosophical writings, gives me a much-needed reality check.

I rather wonder what our descendants will marvel at that we are doing.

Will they think that it was ingenious to design machines in different parts, from different materials, then assembled and shipped to where they are needed? With the limited technology and methods of our time? That we used to engineer and create special machines for these different purposes because in their world, everything you can conceive will come out of replicators [0] instead? Fully functional, no matter which materials it consists of? And humans no longer involved in the design process because a solution was computer generated after stating the purpose of the tool?


People always think of a technology that does everything for you (like a replicator). But often the sweet point is making something easy enough that it can be done by a busy person without needing lots of expertise. And ideally the task can be made fun and fulfilling. That is true of making, modifying or even designing something.
the thermic engine would amaze the next generations
Having good lyrics in music?

Poetry that actually sounds good?

Paintings that make sense and take skill instead of bullshit art?

Repairing relationships and mending things?

Cooking for themselves?

They will marvel at the transistor.
I'm biased, but I agree. I think the impact (as well as the marvel) is underestimated. It hasn't made the splash that antibiotics or fission did, but it underpins subtle, continued advancement in almost every other field. For example, any field that benefits from simulating physics- weather models, aerodynamics, fluid dynamics, nuclear physics, or protein folding.

One specific marvel is the self-aligned gate (

>> They will marvel at the transistor.

> I'm biased

Nice pun.

There is absolutely no difference between a human from 6000 years ago and one today. You could be an Einstein level genius back then, and likely unable to use any of those skills other than for the optimization of your environment. Also, you likely would not be able to use the bulk of it because your education would be non-existent, so your IQ compared to someone today would be much lower even though your raw intelligence would be higher. Essentially you'd be given an exquisitely crafted very blunt knife.
The Egyptians built the pyramids without computers or modern construction equipment. Building the Great Pyramid of Giza today would be a massive project even with modern technology. Yet someone figured out not only how to build it, but organize the workers, the logistics, and manage a long term project without much more than a reed and papyrus.
We have built better pyramids with modern technology. Luxor LV has comparable size but provide much more utility. Transamerica Pyramid and The Shard dwarf Egyptian pyramids.
>Building the Great Pyramid of Giza today would be a massive project even with modern technology.

Only because we expect a far lesser fraction of societal productivity to be spent on them.

I don't know if anyone's run the numbers for the pyramids but European castles and cathedrals took a massive fraction of their area's productivity to create compared to modern civil engineering products.

Recreating the pyramids would only be "big" because modern society doesn't spend big on vanity projects like that anymore. With modern tech we could build the same pyramids much cheaper or many more pyramids for the same money.

> you likely would not be able to use the bulk of it

Evolution rarely produces something useless, especially something that consumes a lot of precious energy like the brain.

More likely these people were exquisitely knowledgeable about their environment.

Either that, or their brains were the same size as ours, but far less efficient.

The human brain has actually been shrinking since about 40k years ago. There is some correlation between brain size and intelligence, but admittedly it isn't too strong.
How much of a change? Citation?
There is indeed a citation about this higher up in the thread.
Neandertal brains were larger than h. sapiens. (

Whether this means Neandertal had greater cognitive capacity, or sapiens brain is more efficient, isn't clear to me.

Thats just... dude, 6000 years ago the knifes where sharper than what you find in your kitchen. What blunt knife?

Similary, high IQ people today are given "blunt knifes" considering they are surrounded by 8 billion retards, see handling of covid, climate change, flat earthers etc. If anything, back then a high iq person would have motivation and belief in bringing discoveries to the table. Today, why would anyone invent say fusion power or usable super conductors when you know it will just be use for more poverty and destruction?

The average size of brains has been lowered by 15% from then to now.

Bronze knifes are bad. Malnutrition sucks. Life expectancy (if surving birth) was 30 years.

But I am sure they would handle covid better ;)

Exhibit 1.

All the worlds information at its fingertips yet it still perpetuates a misunderstanding.

> Life expectancy (if surving birth) was 30 years.

That was average lifespan that includes child mortality. Once you survived puberty, chances were high you will live to your sixties, at least.

Also, compare Africa ~50 years ago and today.

Nutrition, disease load, epigenetics.
Many of the cool gadgets are premised, directly or indirectly, on vastly greater energy access.

Prime movers activate transports, lifts, and pumps. Energy and process controls yield more and more uniform or tuned materials. R&D is a phenomenally expensive, but cumulative, process yielding large returns with time.

Precision measurement, coordination, communication, logistics, mamagement, modelling, quality control, and other advances are all based on that initial bolus of energy provided when we realised we could dig and pump up ancient burnable biomass.

Ancient technology was very often no less innovative, only vastly more constrained.

I had this feeling recently reading Voltaire quotes >200 years old, but could have been written today :)
We are not that smarter. We just have scientific method and better power sources.
It's a pretty typical mistake.

We are just as smart as our predecessors. We just have a much higher population, a higher % of them are well educated, and we have an enormous body of historical knowledge (as well as easy ways for anyone to access it).

"On the shoulder of giants" etc.

You're generally right, but missing an important detail: nutrition.

We are not smarter than the subset of our predecessors who had the privilege of developing without ever starving.

Hopefully a rise in atmospheric CO2 doesn't start counteracting improvements in nutrition.
There is evidence that overeating can lead to cognitive impairments so I’m not sure at a population level we’re ant better off.
> We just have a much higher population, a higher % of them are well educated, and we have an enormous body of historical knowledge

Specialization and trade accelerated with the Industrial Revolution as well; Adam Smith’s division of labour combined with man’s propensity to truck, barter, and exchange.

We are actually getting stupider because of the raise of CO2 consentration in air.

A more reasonable interpretation of that data would be that we're getting stupider because we spend more time indoors without proper ventilation.

Even if we doubled yearly increases in ppm we'd be a century away from a measurable impact on human cognition for outdoor air.

That study looks extremely well done.

A couple of other studies showed no effects of elevated CO2:

See "Flynn effect"

Most interestingly "Research suggests that there is an ongoing reversed Flynn effect, i.e. a decline in IQ scores, in Norway, Denmark, Australia, Britain, the Netherlands, Sweden, Finland, France and German-speaking countries,[4] a development which appears to have started in the 1990s.[5][6][7][8]"
> It's a pretty typical mistake.

It's an even more typical mistake to believe that our time is the pinnacle in all respects (because of all the cool gadgets that we have). But we are not the pinnacle in all respects; perhaps the largest danger is that we are delegating all multifaceted work (which ultimately is what produces skill) to automation and/or extreme specialists, so that we can push the enjoyment button (or take the enjoyment pill) in solitude without end.

We are on a path to an 'Idiocracy' type of society which would likely have been an abomination to generations past if they were to see it.

Less work is a good thing.
Less mindless and debilitating work is a good thing, but to replace work that challenges human capabilities in all its aspects with leisure and enjoyment is probably not a good thing.

If for example reasoning was automated (we're not there yet, but it is on the horizon) then human capacity for nuance would likely diminish further, to the extent where concepts and ideas might only placed in a 'good' or 'bad' category without capacity for further analysis ...

The work is the problem, or should I say, jobs - not the activities. The problem is with people being forced to spend most of their lives fighting for survival. In the past it was toiling in the fields 3/4 of the year to have anything to eat. Today it's toiling in factories and offices to have money to pay for the house, food and medical care. The less time is spent on that, for the same level of quality-of-life, the better.
While I agree in principle, I don't think many humans are capable of what you want. Without a desperate need to work, most people don't seem to bother doing much even it that would give them great satisfaction. Just look at almost every unemployed person who has a place to live and food to eat but nothing to do all day. Why aren't they spending their plentiful time on high quality of life activities?

This might be hard to imagine if you're well educated, already working, and in your 20's and the world seems full of excitement and opportunity but you're held back by the annoying need to pay your bills. If you didn't have to work, you might start a business or spend all day on your side project or whatever. But most people aren't in that position. Often, their only sense of fulfillment comes from their work no matter how unpleasant it is, and they only work because they have to to survive.

I would like to reply to just the first sentence of your post. While I agree that just being leisurely and seeking enjoyment rarely leads to long lasting meaningful experiences, I do not believe we humans are striving to replace all work with those activities. There are many examples of people who have the possibility to do nothing but enjoy themselves and they still push their capabilities and try to find new challenges. Leisure is nice, but only leisure gets boring.
Certainly nothing a bit of extra theology and geometry won’t fix.
I disagree. As humans, we have a tendency to be pessimistic, but we are in aggregate enjoying unprecedented peace and prosperity, have done for an unprecedented length of time, and data point to that continuing. The leisure that many of us enjoy is a byproduct of that trend.
Peace from violence between sons sent off to die for no reason. Sure.

Peace from violent thoughts leading to depression and anxiety which are at all time highs, no.

Not to be negative, but 1871-1914 was fairly peaceful in Europe and North America as well.

There were Balkan wars and there were Indian wars, but the vast majority of Western population never served in combat.

And people started thinking that this is how it is going to be forever.

That period only seems peaceful because the French had just been massively humiliated in the Franco-Prussian War [1] in 1870 and the powder keg had just been reset. The people of France were itching to go to war with Prussia/Germany to reclaim Alsace and Lorraine. Which created a massive arms race till WW1. Also, while Japan isn't in Europe, the Russo-Japanese war did happen in 1904 in that period resulting in a major loss of trust in the Russian monarchy and the subsequent 1905 Russian Revolution. The Europeans were still sending troops to aid in the subjugation of Africa (Boer wars, Anglo-Zulu wars etc) even then.

However, I do agree with you that people then thought that world peace was achieved. The 1910 book "The Great Illusion" [2] ironically argued European war was unlikely to start due to the great economic costs of destroying trade between nations. It got the consequences right at least.

[1] [2]

> The people of France were itching to go to war with Prussia/Germany to reclaim Alsace and Lorraine. Which created a massive arms race till WW1.

Eh... not really. Anger at the loss of Alsace-Lorraine peaked in the immediate aftermath of the Franco-Prussian War, when France couldn't do anything, but by the 1880s and 1890s, France had resigned itself to the loss. The massive divisions in French society under the Third Republic meant that it was in no position to do anything to reclaim it. A parallel might well be drawn to Finland's position today over Karelia: they'd certainly like it back, but they're not about to fight for it. It wasn't until World War I broke out that restoration of Alsace-Lorraine to French rule really became feasible, and hence it became a major war aim, but it wasn't a factor until after war had already broken out.

The arms race in question is the naval arms race between Britain and Germany, which itself subsided in 1912 because Germany couldn't afford to keep up.

> As humans, we have a tendency to be pessimistic

Maybe, but it is not because we tend to be overly pessimistic in general, that serious problems cannot happen to us. Entire civilizations have diapered in the past, so we should remain vigilant.

After all, another bias that humans have, is a strong tendency to believe that what is true now, will remain true forever.

Very, very, very true. The light of civilization is a flickering candle in the darkness

I often think about the city-states along the Silk Road: healthy, peaceful, cultured, unprecedented prosperity for their time. All defeated when the hordes of Genghis Kahn rode by, many utterly destroyed

The Empire of Mali. The Kingdom of Lithuania. Macedon. Tyre. Babylon. Carthage. Samarkand. Assyria. All once mighty, all gone, perhaps a place-name remains, if that

> The Empire of Mali. The Kingdom of Lithuania. Macedon. Tyre. Babylon. Carthage. Samarkand. Assyria. All once mighty, all gone, perhaps a place-name remains, if that

Aside from perhaps Macedon and Carthage (indirectly via Rome) most of those don't even warrant a mention in the high school history curriculum (in the US, at least).

history starts at 1700 when columbus discovered indians?
Not far off. IIRC, my freshman year history course (at a high-achieving school, no less) covered world history from the agricultural revolution until 1500 CE. That's ~14000 years (call it 4000 of knowable history). There's not a lot of time for anything other than "Don't forget, there were lots of other extraordinarily successful civilizations we know about that were less influential on our intellectual forebears".
I've seen the high school world history books of my nieces and nephews and all of those (except maybe lithuania), were at least mentioned in US schools. Other civilizations ranging from the maya to the khmer were also included. By necessity, none of them are examined in depth but they all got at least a few pages.

The simple fact is that pre-industrial history has had literally thousands of different thriving civilizations around the world. It's simply not possible to even briefly cover anything but a fraction of the more "important" in a non-university setting.

>> The Kingdom of Lithuania

For anyone still paying attention, I should have written "The Grand Duchy of Lithuania", which was a powerful state for hundreds of years in the Middle Ages

The Kingdom of Lithuania, while also powerful, lasted about 2 years

This has really brought out the eugenicists, it seems?

But you're absolutely right; we get to use the infrastructure, explicit (written) knowledge, tacit knowledge of our society, social structures, institutions, legal systems, property distribution, and peacemaking of our predecessors.

Our brains decreased by a golf ball size in the past couple thousand years.

It is much easier for stupid people to survive today.

[citation needed]
Intro of the movie "Idiocracy" sums it up pretty good ;)
It is well known that Sperm Whales have long ago figured out how to unify quantum physics and general relativity. They could tell us small-brained humans but apparently they enjoy watching us struggle.
Brain size does correlate with intelligence WITHIN a species.
Neural density seems to be what matters.
Yeah, people seem to be getting denser by the year.
Well, that's true in the sense that it is easier for everyone to survive today. That includes both the smart and the stupid.
We work harder than our predecessors (8+ hours workday, 5 days a week, both men and women), so I'd say we aren't really as smart as them.
As opposed to 12 hours a day (depending on daylight), 6 days a week, both men (in the fields) and women (at home, without the luxury of washing machines and vacuum cleaners). Yeah, we certainly work harder...
Modern farmers in rich countries will pull 16+ hour days 7 days a week during harvest. Admittedly they're in tractor cabs listening to the radio rather than running around with a scythe, but the hours are long and the work's boring.
For women "at home" often means bulk of animal care, home production of goods (crafts basically) and other similar farm-like work. And having jobs in cleaning, sewing and what not. It is not like every one of them had living husband or every husband earned a lot.

Good case are miners areas - men work hard like 12 hours a day under ground and die young. Women have to earn for themselves and for kids once they are dead however possible.

Good point. Children are animals.
Milking cows, goats, general care about chicken and what not was typical female work in traditional villages. Also, field/garden work that do not require that much physical strength was done by women too.

1950 middle class household is not all there is to be about how historical families existed. Most of the time, the amount of work to do was basically infinite. And the more "anyone" could do, the better. That includes 6-7 years old kids who were already expected to be useful. (Here the kids started to work at 5, they would pasture gooses, which is super easy but was to large extend unsupervised).

Also, origin of kindergarten are German cities where both parents worked 12 hours a day in factory and small kids were left to own devices whole day. Obviously we are talking about poorer people here, but poor were large part of society.

Also, asshole.

Interesting video on the Time Ghost channel. It wasn’t until industrialization that idea of “men work, women stay home” came about. In an agrarian society, the entire family worked. Yes, there was division of labor between men and women, but it was more like “men plow the field” and “women pick the crops”. Even with newborns, the women were out working with the kids strapped to their backs.
The video doesn't show all the people doing all the work, likely from dawn till dusk. It was all man- and animal-powered.

Construction, for example, is incredibly hard work even with modern tools, and they had none of those.

That we can live comfortably with all the modern amenities on 40 hours a week, which for many is just sitting in a chair, typing text, is really good. I'm not bashing office workers here, btw.

Could definitely work less, maybe the push for shorter work days will gain traction.

That statement feels wrong but I have no data to back up my gut feeling. Only a handful of generations ago even something as menial as doing your own laundry was hard work. Maybe we spend more time in offices, but if anything, I suspect we work a lot less hard in general.
For most of human history most people didn't "do" laundry.
Maybe if you count prehistory when people wore animal skins or walked around in their own fur. But as long as there's been fabric, there's been laundry. The documented history of laundry goes back to at least ancient Rome, where fullones (usually male slaves) did laundry. In the early middle ages women started to take care their household's washing needs.
It depends what you mean by work. I read an article a few months back which was saying that the addition of "modern" technology washing machines and the like doesn't give you more free time, it gives you the opportunity for doing more things so you feel more busy and tired because you are doing more things in the same amount of time!
You ... don't know much about lifestyle of men and women in the past, do you?

With exception of very rich people in few periods (idle aristocracy, middle class 1950 household), majority of people needed to work a lot. That includes both women and men.

Back in the day people used to work 16 hours a day and sometimes more.
We work harder? Seriously?

Most of the time in human history people were struggling to even stay alive. You had to work until you got enough food to feed your family, or you'd die. Live was not great, it was very stressful and inefficient (but people were used to it). This is still the case in most of the world, although overall not as bad as it once was, it is improving constantly.

We're the lucky ones who can sustain ourselve with 8 hours of work, food is cheap and abundant, we can afford luxury items like iphones even if a 300$ android smartphone would do the same job.

No, at average, people are not working harder now, because we don't have to. We managed to improve efficiency so much already and quality of life continues to rise.

Hunter gatherer societies are theorized to have spent the majority of their time not working, which is partly why were evolved such a complex social dynamic. Hunters would patrol their territory and hunt, with mixed results on the hunting, and gatherers would spend a few hours gathering food. It didn't take much work to sustain their tribes.
I wonder how much that depended on the population density of a particular place vs its "carrying capacity". I imagine that our hunter gatherer ancestors who lived with more competing groups fighting over diminishing herds probably spent more time/risk defending their turf.
We haven't improved efficiency at all, it takes far more resources to keep a person going today than it did in the 14th century. It takes a couple decades of education before a person can even begin to enter the workforce. Raising kids was once an investment, now people can barely afford to raise 1 or 2.

Our inefficient stuff is made by people in foreign countries working in factories whose lives really aren't any better than middle ages Europe.

Also, People like farming and hard physical labour. In the suburbs every household has a little miniature hobby farm that yields a useless crop, and people farm it for fun over and above their regular job. When people don't have to do any hard labour as part of their job, they go to a gym and pay money for the privelege of moving heavy things around even though it serves no practical purpose.

All this inefficiency is destroying the planet, which is the dumbest thing of all.

"Our inefficient stuff is made by people in foreign countries working in factories whose lives really aren't any better than middle ages Europe."

Life expectancy in the most typical manufacturing hotspots is actually better than Western standards of 1900. Even poorer countries today have much better healthcare than Queen Victoria used to have. Middle Ages is right out in this comparison.

These are gross generalizations.

> It takes a couple decades of education before a person can even begin to enter the workforce.

This obviously depends on profession. On the contrary, you no longer need to go to college or trade school since everything is online. Seriously, it's amazing how proficient some of these children can get just from YouTube videos.

> Raising kids was once an investment, now people can barely afford to raise 1 or 2.

Hey at least you have a choice now. Before, raising lots of children was almost a necessity in order to help around the farm. Now things are so efficient that you really don't need to raise children at all.

> Our inefficient stuff is made by people in foreign countries working in factories whose lives really aren't any better than middle ages Europe.

Can you provide evidence on this?

> People like farming and hard physical labour

Most people would probably disagree with you on this. There is a big difference between occasional hard labor and doing hard labor every single day. It takes an enormous toll on the body.

> When people don't have to do any hard labour as part of their job, they go to a gym and pay money for the privelege of moving heavy things around even though it serves no practical purpose.

Isn't the purpose to be healthy or look better?

>We haven't improved efficiency at all, it takes far more resources to keep a person going today than it did in the 14th century.

We very much have. We couldn't support our population with 14th century levels of efficiency. We wouldn't have enough farm land, fresh water, etc, etc.

He might mean energy efficiency. We just have access to way more energy these days, and we've been slurping that milkshake hard.
Your confusing hardness of work with grimness of life. No one was working 200hrs/week to make polio vaccines from themselves.
It's funny - you're both right.

Peasants (over 90% of the society) were usually working less hours but much harder than we do. And they were living in much worse conditions of course.

Farming (especially without modern technology) is very cyclical, most of the time you have too much labour and too little land/food. Then for a few months you have too few people to do everything that needs to be done.

And there was no easy way for vast majority of people to store surplus for more than a few years. And there was a real possibility of starvation if a few factors independent of you happen at the same time.

So the whole society and economy was structured around these constraints - that's why it doesn't follow our intuitions. It made no sense to increase gains by 10% if you had to increase risk by 1% to do that. It made no sense to work harder if you have enough and it's gonna spoil anyway. You're just risking injury to throw it all away later.

There was a great series of articles about it:

The "On the shoulder of giants"-quote made me think of this:

"It has been said that the great scientific disciplines are examples of giants standing on the shoulders of other giants. It has also been said that the software industry is an example of midgets standing on the toes of other midgets." -Alan Cooper

The version I'm familiar with, though I don't know the original source, is "if we have seen less far than other men, it is because we have stood in the footprints of giants."
There's so much about programming that I just don't know because someone else abstracted it away from my responsibility.
If you haven't, learn to program in assembly. Everything else is built on top of that.
If you look, you'll find that there're plenty of levels below assembly.
Let me get my magnetized needle.
It's from Newton, who it is thought was aiming a barb at Hooke.
An etymological note.

I'd known that most in Slavic means "bridge" dating back to the destruction of the famed Stari Most ("Old Bridge") in Mostar (named for the bridge, or its keepers), Bosnia and Herzegovina, in November 1993 during the Croat–Bosniak War.[1] The bridge was rebuilt in 2004.

A related English word is mast:

> "long pole on a ship, secured as the lower end to the keel, to support the yards, sails, and rigging in general," Old English mæst, from Proto-Germanic masta (source also of Old Norse mastr, Middle Dutch maste, Dutch, Danish mast, German Mast), from PIE mazdo- "a pole, rod" (source also of Latin malus "mast," Old Irish matan "club," Irish maide "a stick," Old Church Slavonic mostu "bridge").

This is also probably the source for Mosul, the city in present-day Iraq, from the Arabic al-Mawsul, literally "the joined," refering to the bridge there.

Bridge itself comes from proto-Germanic brugjo, "log, beam".

The French pont is from Latin pons, bridge, earlier "connecting gallery, walkway".



1. Also called Mostar Bridge, which since the city was named for the bridge-keepers, is a double and self-referential toponym: bridge-keeper-city bridge.

The one thing I don't understand is how the original posts were driven into the river bed. You have to deal with the current, deal with the fact that wood floats, deal with a long post, have to have a means of driving it down far enough, etc. I imagine that nowadays they'd use a pile driver on a huge barge with engines that can automatically compensate for the current, but I can't imagine what the equivalent was back then.
You could pre-soak the wood so it's less buoyant, and hold a barge in place with ropes to the riverbanks. I'm not saying that's how they did it, but that's what I would try if I were them. You'd also want to pick the right season when the water flow was the least. You might even be able to dredge a channel so that the water is directed away from the position of the supports. I doubt they had a means of controlling the river flow back then, so I doubt they could have redirected the river into a temporary side channel, but that could also help if possible.
Good question. The video shows the first posts floating in air across the river and dropping magically in-place. These posts are then connected into a kind of scaffolding for the caisson [1]. A pile driver is built on top of the scaffolding that is used to drive the remaining posts that make up the caisson wall but they don't show what powers the pile driver (men?) nor how it is moved post to post along the scaffolding. A water wheel is used to lift the water out of the caisson.

The posts are small compared to modern piles so they will not be overly buoyant. Modern piles are core structural components that are used instead of a caisson so they are quite big.


I'd assume they would put them into place using helicopters
The thread mentions wooden piers and low tech pile drivers.
Maybe the original posts didn't need to be that deep--just deep enough to be used as scaffolding for the wooden version of the pile driver to be set up.

They may have also taken advantage of fair weather and seasonal changes. During the dry season, the river would be lower and easier to work with.

IIRC the water under the bringe is actually behind a weir (to aid river navigation). If the weir was already there back then, they could temporarily open it up and significantly lower the water level.
I was in Rimini, Italy a couple of years ago and came across an ancient bridge called Ponte di Tiberio[1]. It's mind blowing to see modern cars plying on a bridge that was built nearly 2000 years ago.


Roman bridges have their own list article on Wikipedia:

Also relevant: Hardcore History's "Thor Angels" episode has some great insights over the post-roman life in Europe.

Note that the construction took 45 years.
It's to bad the animation doesn't convey this information very well. Also all the manual labor and additional tools like boats involved. At the beginning the poles just fall out of thin air until they use some sort of pile driver to ram them in.
Isn't this longer than the average life expectancy of that time? I wonder what kind of incentives they had for such long-term projects.
As others said, it isn't. Child mortality was particularly high, which reduces the average age, making it not very suitable for understanding the reality at the time. Barring violent death, people who survived past the age of 15 normally lived to 60+.
“Average” lifespan is a misleading metric prior to the early to mid-20th-century because it’s heavily influenced by those who died before age 5.
I'd guess the kings, clergy and nobles liked their legacy and the people generally, then as today, like to work on something that improves society.

And also, the average life expectancy at birth is a lot lower than the age an adult can expect to live to. People got old in the middle ages, it was just not as common, but probably more common for the aristocracy.

> like to work on something that improves society.

like to have other people work on something that improves society.

King wants a bridge, king gets a bridge. Whether it's for the country and people or his own satisfaction, if he could pay or force people to do it, they'd do it.

And bridges were infinitely more useful than fancy castles, for example.

The average was skewed by child and women (during/after birth) mortality.

In lecture [0] the professor mentions as an aside:

> And what is interesting, if you take out the childhood mortality, the Victorian person between 1850 and 1880 lived slightly longer, if he was a male, than you do today

That's well after the middle ages, but still also well before modern medicine and technology, such as good sanitation and water systems.

[0] (has the full text to search for the context of the quote)

That’s an interesting claim. I guess it implies that although we’ve reduced childhood mortality, the people we’ve saved go on to live shorter than average lives?
Dental work is also a big driver in longevity, as is washing hands by doctors.
Can you expand on this? Were abscesses killing people or something else?
You know the very extreme of dental issues, nerve infections? Well, they're the very extreme because when it gets to the point of aching intensely all the time, anyone gets treated in a matter of days.

If there's no treatment, it keeps moving in.

One of the things that always puzzled me about human anatomy is why the heck are there nerves inside the teeth?
I find that suspect. 1 because I doubt statistics for the poor were as accurate, and 2 because people alive today aren't dead yet so we don't know their life expectancy, which has been steadily trending upward for a century even for middle aged people.

It was fast because they didn't have to go through an environmental review process ;)
Those little intermediate piers were probably the slowest part of the on site work. And the most vulnerable part of the bridge, because that's what gets eroded. It's still the biggest cause of bridge failure.
This is what I was curious about, how long did the coffer dams take to erect and pump out and were they done separately or two or more at once?

Still it seems that video makes it look far simpler that it truly was. Just the carting of the stone from quarry to the job site had to be an immense undertaking

Makes me wonder if they've been done in parallel or serially.

Also, I'd love to know how the bridge was designed. How did they figure out the shapes of the supporting structure, or location of the piers? Etc. We have this knowledge systematized today, but we use mathematics in a form that was developed much later than those bridges.

They had it systematized as well; the mason guilds were very thorough in protecting and maintaining knowledge throughout centuries.
Makes me wonder if they've been done in parallel or serially.

Depends on the site, probably.

Driving the first piles had to have been a tough job. Still, Caesar's legions did it to cross the Rhine in 55 BC. So pile-driving in water was being done a long time ago.

According to JE Gordon in “ Structures: Or Why Things Don't Fall Down,” the answer is surprisingly simple: everything was massively, tremendously overbuilt.

Also, often builders would start with scale models, and then exaggerate proportions - that doesn’t require sophisticated math. Just do the modeling “analog”!

To see how overbuilt they are, you have to compare to late masonry stone arch bridges that are more 'airy'. Like so

Other places may have done it that way, but the Swiss simply subcontracted their bridges to Satan:
Someone should make a video game about that. You play as the devil and construct bridges!
medieval trope's_Bridge
Awesome! I figured there was more than one, but I had no idea how many there were, and how closely related the legends.
If you have seen the TV series Hinterland, the one in Ceredigion in Wales plays an important role.,_Ceredigion
It looks similar to the description of the bridge being built in "World without End" by Ken Follett. One bit that is missing from this animation is that there is no rubble placed in the water around the piers. In the book this had the all important function of preventing the foundations from being washed out by the river. Maybe that was fiction or it was too much detail for the animators since the water is not transparent.
Oh wow.

> In 1496 the third arch (counting from the Old Town side) broke down after one of the pillars lowered, being undermined by the water (repairs were finished in 1503).

So that suggests there were no, or too little, defences against washout of the foundations originally.

Or, no divers inspecting the pillars and foundations against erosion. It was easy to get complacent in the old days, after the Engineer died, and just assume the old monuments were eternal.
Yeah, my first thought when seeing the cofferdam was "hey, I know what these things are!"
I expected there to be some kind of "foundations"?

i.e. once the water is out of the enclosure, you have a surface that is likely to be soft wet mud or sand. Surely you want to scoop some out, dig down and lay some big blocks of stone under the river bed level?

Or maybe that happens, but was just not shown. Or maybe, once you start building up, the sheer weight pushes the whole column down until it settles.

In the book the issue was that the sand around, and eventually under, the foundations washed out over time so the piers started to be effectively suspended from the bridge rather than supporting it. Rubble around the actual foundations were needed to defuse the drag of the water around the foundations, preventing the washout.
Dig to bedrock or drive in pilings to shore up your foundation if you can, it all depends on the local geography. Given the lateral forces on a bridge it seems unlikely that modern builders would float the footings of the arches in the riverbed, but in the case of this bridge I think that was what happened (a guess given the fact that three arches failed during a flood in 1890s when a pile-up of logs and debris forced a lot of water flow to push deeper to pass the bridge.)
Thank you! Seems very similar to the bridge in Córdoba:
there are many moreábrica
yeah I imagine once a technique is mastered, it would be used all over the place! Not sure if one "company" started offering this service in many places, could explain the similarity.
I'd rather call the knowledgeable entity in question "expert" than company, but I was wondering along similar lines: would they travel far to projects or would the knowledge be dispersed to enough people that most projects could just happen with local expertise? (plus temporarily imported capacity for big project, but not necessarily imported expertise?)

What's clear is that knowledge transfer (from region to region and from generation to generation) was facilitated by traveling apprentices, a tradition that still lives on and (I believe) is documented to go back to that time. Their profession wouldn't be bridge builder but merely some contributing role (with the occasional exception of whatever the period-correct term for architect or project manager would be), but of all the masons involved, you'd have some whose learning circuit involved a bridge, of the woodworkers you'd have some who dabbled in cranes before and so on. But was that usually sufficient or was there also a pattern of on-demand traveling leadership?

edit: post was lingering in the input form for some hours, some good answers already there!

These projects employed skilled journey men (level between apprentice and master). At some point they then traveled to work on the next project, spreading the know-how. Once something was working, it was often copied as modifications were risky.
To add to this: those were highly sought after specialists with a lot of privileges. This had consequences that sound strange to us nowadays.

Stonemasons were heavily involved in medieval diplomacy, since everybody in power needed them to build or repair fortresses. They could travel freely between kingdoms that were at war with each other and exchange messages between the respective rulers.

That's a fascinating take but not strange at all since modern-day equivalents still exist in highly-skilled occupations like CPU design.

Perhaps a comparable example would be an executive with a technical background: Jim Keller has highly sought-after skills desired by chip makers.

They were the tech aristocrats of their day.
I believe it’s Charles Bridge of Prague
Really similar! To be honest I think I have seen many similar bridges all around Spain and Italy, not just Central Europe.
this type of bridge is common throughout Europe.

since antiquity

Animations like this have amazing information density. Think how much harder it is to explain how they built these bridges using language.
Yet also convey false information in exchange for elegance of the animation.

For instance, the first layer of stones across the arches builds up from one side, over the top, and down the other, rather than up from both sides to meet in the top with keystones.

How about reactive informal learning?

Informal learning, at places (eg museums) and on the web (education and outreach sites), is a recognized and institutionalized part of public education and outreach. And when something, like this gif, catches public attention, related resources will be linked. A little bit. In an unprepared, ad hoc, shallow, and unfunded kind of way.

A "teachable moment" is an transient opportunity to offer insight. And unplanned opportunity, but one a teacher trains and prepares for.

With viral content reaching so many, are we missing an opportunity by not being organized to exploit them as teachable moments? To rapidly and reactively link related content? History, transport, economics, construction. Might not a spike of viral be broadened, by better facilitating people following up on whatever aspect of the spike tickled their interest?

The compressed timescale makes things harder. But also easier - coping with the severe content-creation bottleneck of copyright is easier in a transient context.

How might we explore this space? Perhaps strengthen the existing "here's something related and interesting" pattern by aggregating and propagating such? A tweet "here are some links from HN", and an HN comment "here are some links from the twitter discussion"? Those are variously suboptimal, so what else?

Great video, but could have used a scale reference. The pile driver at 00:21 looks to me to be about 30-40', but the wikipedia page for pile drivers suggests it's probably <25' tall.

It's also unclear how the piledriver gets re-positioned for each pile. It does not look readily movable.

TIL that pile drivers are a real thing and not just a sex position.
Pile driver could be as simple as an a-frame and a bunch of guys with a ropte, a pulley and a large rock. No need for such advanced gear, but it makes for a nice animation.

I recently came across a video of some middle Eastern guys digging a well using a similar technique. They added a little water down the well and repeatedly lifted and dropped a heavy pipe on it using an A-frame and a pulley. Was surprisingly interesting.
So so very cool. Saving this in the reference pile, for when people argue “we are more advanced as a society” extrapolates to “I am more advanced as a person”
It's interesting that this bridge is still around. It seems like most of that society's energy was concentrated on building this bridge, and physical infrastructure of that nature. Its best minds and hands were at work.

Similarly, in San Francisco, many people live in 100 year old houses. It's not like we discovered better "must have" ways of building houses that made the old ones obsolete.

I honestly think things like the Linux kernel (going on 25 years) and LLVM (going on nearly 20 years) will still be around in 100 or 500 years, and basically nobody will have the time or a reason to rebuild them. Kind of like the PC BIOS is still around.

People won't really be working much in those areas, but rather on top. Just like we kind of build "on top" of houses now. It's infrastructure that we can use to make progress in other areas. It reminds me of "How Buildings Learn" by Stewart Brand.

> Kind of like the PC BIOS is still around.

Not any more. The BIOS has been replaced with UEFI on most new machines for about a decade now.

Yeah that is the thing that runs an entire OS right :) Like Minix or Linux.

Still I bet the BIOS will still be around in many places. What about QEMU? Does it present a machine that contains a BIOS?

A google search turns this up:

Which means that OSes still have BIOS support.

It's not my area of expertise, but it seems like turtles all the way down.

BIOS may not have been the best example, but Linux itself or Minix may be a good one. If 100 years from now there's a new dominant OS, there's probably going to still be UEFI with some legacy operating system booting it up ... Or something emulating UEFI, etc.

A weird example since a 1920s San Francisco house was really a local nadir of domestic architecture, slapdash work that was adequate in a time of abundant wool and heating fuels. Most 1920s SF houses aren't worth what it would cost to dismantle them, or at least they wouldn't be if there wasn't a land use and planning crisis in that city.

A modern house would have a tiny fraction of the energy demanded by 1920s SF tract housing, and 100% less interior mold.

Is this similar to how the romans would have built bridges 1000 years earlier?
Nice animation, but I bear in mind that stuff that is presented like this is really just hearsay - we don't really know that it was built as presented. It could well have been built as shown - its a plausible hypothesis. But it is also plausible that the bridges were only built in the 18th century. Or maybe they were built 100's of years earlier.

With any historical claims, we should have access to the source to be able to confirm.

On the wiki page that was posted we read:

"Throughout its history, Charles Bridge has suffered several disasters and witnessed many historic events. Czech legend has it that construction began on Charles Bridge at 5:31am on 9 July 1357 with the first stone being laid by Charles IV himself. This exact time was very important to the Holy Roman Emperor because he was a strong believer in numerology and felt that this specific time, which formed a palindrome (1357 9, 7 5:31), was a numerical bridge, and would imbue Charles Bridge with additional strength.[4]"

Where 4 is:

"Frucht, Richard (2005). Eastern Europe : an introduction to the people, lands, and culture. 1. Santa Barbara, CA: ABC-CLIO. pp. 251. ISBN 9781576078013."

When you search that book on though, there are no references to "1357", "5:31", "numerology". There is a single reference to "numerical" but this relates to 1944.

So we have a paragraph in wiki, that has some very specific information, that it claims is from a book that doesn't seem to contain that info.

This is to say that 'we' don't know anything about this bridge - the sources do not check out.

I was hoping to get a little further than this. I wanted to track the primary or secondary source for this claim about the bridge build date. But I couldn't even get that far.

What should one conclude, when the detailed information being provided does not check (or should that 'Czech') out?

You can find better references in the czech version of the wiki articleův_most

Basically, it is just a hypothesis by some astronomist. Contemporary chronicler recorded just the year that the construction was started

My Czech is not the best, if I'm honest...

So, your reading is that its a hyposthesis by some astronomer. And that someone chronicled the year construction started.

If you are able to provide sources for those, that would be interesting!


The reference is this articležení_Karlova_mostu_a_ko...

(alert: scanned and turned 90 degrees, my neck hurts)

On page 202 it describes founding of the bridge. The author puts it in context of gathering the remnants of St. Vitus (that Charles was obsessed about and his statue is present on one of towers at the end of the bridge) and highlights that the conjunction (opposition) of Saturn and the Sun happened on 1357, 9th day of 7th month.

He further investigates whether the way Charles or people of his age would write the date is the same as ours and concludes that it is likely - arab numerals, year, day, month then time, 60-minute hours are all documented in his court. Founding of the bridge would have to include a mass so it could not take place in the afternoon, which 5:31 AM isn't. Indeed different ways of expressing time used at the time are all consistent with that - except the "old bohemian" way to express time because that would be before sunrise.

If they did express it the same way as we do then at 5:31 AM the constellation of Lion (symbol of Czech kings) was in ascendent (just above horizon, important astrological place).

Additionally, a sign (which was dated to 1640 but could have been a replacement of an older one) on one of the towers at the end of the bridge contains a palindrome poem (in Latin).

Another reason why it could be true comes for the author from the fact that Charles and his people would have known and read Dante Alighieri's Vita nuova where similar numerological symmetry plays a major role. And the Prague Astronomical Clock contains a completely extra gear that serves no purpose but the counts of its tooth is also a palindromatic sequence.

Actually, if you find a better version of that book than the one on, you can see this info on page 251. I'm just looking now... Not sure why this isn't found in's search.
In the book, it says:

"Charles BridgeAmong the best-known architectural features of Prague is Charles Bridge (Karl¿v most). Known as PragueBridge until 1870, it spans the Vltava River and the Kampa Island between the Lesser Town and the OldTown. It is one of the oldest stone bridges in Europe and the second oldest in the republic (the oldest inPísek, Bohemia, was built in the thirteenth century).The first bridge crossing the Vltava in Prague was wooden anddated from the tenth century. The Judith stone bridge, built 1158–1160, spanned the river until a disastrous floodwashed it away in 1342. Charles IV commissioned Petr Parlérˇ to erect a new bridge; being somewhat superstitious,the king broke ground for the bridge in 1357 on 9 July at 5:31 A.M., thus creating a date and time that, if given com-pletely in numbers, is a perfect palindrome: 1–3–5–7–9–7–5–3–1.

The sandstone bridge, stretching 516 meters with sixteen arches, was completed in 1402.Thirty statues adorn thebridge (the originals for most are in the Lapidarium of the National Museum). In 1683 Charles Bridge received itsfirst baroque sculpture, that of St. John Nepomuk, the work of Matthias Rauchmüller and Jan Brokoff. The bronzerelief at the base of the statue depicts the false legend that Jan Nepomuk would not tell Václav IV the secrets of thequeen’s confession, so Václav IV had him cast into the Vltava from the bridge (a bronze cross in the bridge parapetmarks the alleged spot). Other baroque masters who sculpted works for the bridge included Ferdinand MaximiliánBrokoff, Michal Josef Brokoff, and Matyá≥Bernard Braun. In the classical era, Josef Max, Emanuel Max, and otherssculpted several statues. Karel Dvorˇák completed the most recent statue, that of the missionaries Cyril and Method-ius, in 1938.

On the Lesser Town side of the bridge are two towers.The first is a remnant of the Judith Bridge that was rebuiltin 1591. The taller Gothic tower was completed in 1464, and a Gothic gateway links the two towers. On the OldTown side of the bridge stands a single Gothic tower decorated with saints, the builders, and skillfully executed rep-resentations of Charles IV and his son,Václav IV. Also embellishing the tower are the coats of arms of the Bohemiankingdom.The roof is the design of Josef Mocker from the late nineteenth century. A portion of the Old Town Towerfacade and the bridge was damaged during a Swedish bombardment in 1648."

Ok - so now, I can see where the wiki claim is from. But, where is this source in the history book from?

My problem is that this is presented as true, but I want to know where the sources are. The book "EASTERN EUROPE" by RICHARD FRUCHT, was written in 2005. Obviously we are not dealing with a primary or secondary source. But what is the source Frucht is using? Is it just a story Frucht or someone else made up? We don't know.

At that time clocks did not have minute hands so they would not have been able to measure time that precisely.
That's one part of it. But where is this claim even from? Where are the sources?
> This exact time was very important to the Holy Roman Emperor because he was a strong believer in numerology and felt that this specific time, which formed a palindrome (1357 9, 7 5:31), was a numerical bridge, and would imbue Charles Bridge with additional strength.

This smells like horse manure, not just because it's unlikely anyone measured time that precisely in 1357, but also the Y/D/M date notation looks distinctively American.

Even more smelly is the precision of “5:31 AM.” I am not sure hour:minute was a clear and universal concept in 1357. At the time, “canonical hours” were used ( ); they corresponded to night watches and bell tolling times, and certainly weren’t notated like “5:31.”
Americans use M/D/Y, not Y/D/M. The reason ISO recommends Y/M/D as a universal date format is because just about everyone agrees on how to interpret it -- no one expects Y/D/M.

Not that this makes the claim any more believable.

They used the water currents itself as a pump to empty out the water and create a space to build on - that's brilliant!!
Construction timelapses can have a similar vibe:
Great animation but they seem to have omitted a very key part of the construction process, without which the bridge would possibly not have been completed:
I thought you meant the egg yolks

Got a chuckle from the idea of having to write a project pitch for the science funding: "let's do some experiments to determine wether our bridge is vegan or not!"
Were the cranes human powered? It looks like giant hamster wheels that several humans would be needed to operate?
Yes, similar to shown here:
Yes, they use these to build Guédelon.

Wow. That's a cool project to show how the alien's were not necessarily needed. I've seen attempts at this for the construction of pyramids, but those only really show how moving large stones with human motors were possible.

I visited it a couple of times. The only modern things they use are safety 'tools': Helmet, harness, and ropes are modern, to avoid casualties that were not uncommon when these things were built.
Video in action

Secrets of the Castle, BBC

This twitter commentary on the same video is worth reading too:
This really blew my mind when I saw it for the first time. It still blows my mind. Amazing.
Yeah me too. Also how Julius Caesar crossed the Rhine river is amazing.

"The bridge would need to be four football fields long"

Playing right into the stereotype; they didn't even start with a standard unit.

Very cool, if you like stuff like this check out the building of the Brooklyn Bridge, that's just insane:

I think the story goes that there were less than 10 people in medieval Europe that could do a division on paper at the time the great gothic cathedrals were build. Gets you thinking...(no source provided)
Is it weird that this makes me want to build a middle-age bridge? The part where the water is fully drained and the base layer of rock is being laid is really appealing to me....
at the 14th second, the video shows something like a hammer,

I don't understand it. the hammer seems to ram down wooden pillar at the same location.

I think for it to work, the hammer needs to move around the wooden rail .

Building a Leonardo da Vinci Bridge
Seriously, why is the submission to a lower-quality, sped-up Twitter gif?
This GIF has been making rounds on Twitter for a few days already. I think if I had not searched Youtube for the video, I would not have seen any other version either.

Among others, I'm quite certain that it was also shared by former NASA astronaut Mike Massimo [0] who has quite a few followers on Twitter [1]. (More people might know him from a (few?) cameo appearances in Big Bang theory though.)

It is easy to have seen this on Twitter by now.



Possibly because the original was hard to identify, even for a sufficiently motivated submitter.

Like others, I saw the shorter animation, via Mastodon.

I assumed there was a source video but couldn't find one after an hour or so searching "medieval bridge building", "medieval bridge construction", etc., particularly as the keywords are dominated by gameplay animations.

There are several somewhat related videos on castle construction, employing some of the methods employed on Karlův most, e.g.:

How were castles built / constructed in the medieval period? (~15 min)

Building A Medieval Castle Using Authentic Tools | Secrets Of The Castle | Timeline (~1h)

The first relies heavily on contemporary experience from Guédelon Castle, "an experimental archaeology project aimed at recreating a 13th-century castle and its environment using period technique, dress, and material."édelon_Castle

There are numerous videos of contemporary methods, e.g., Grady Engineering's dewatering explainer, showing the modern adaptaions of coffer dam / cassion construction illustrated in the submitted piece (, various pre-cast span methods ( China especially has developed rapid ( and extreme ( span construction to an art form.

But rigorous videos detailing ancient construction, not so much.

Emailing mods can result in source links being substituted.

It's changed now. We detached this subthread from
I liked the lower-quality, sped-up Twitter gif. It was few seconds that made me interested. I would not watch two minutes long original one. I did skipped through original one after seeing short one.
As _Microft says, the gif is making rounds on the Internet (I've seen it last night on Mastodon).

And to be honest, I'm not surprised that it beats the video - it communicates the exact same information, and the same sense of awe as the original video, but in a much more time-efficient manner. Watching the original now, I can't shake the feeling of how boringly slow it is.

If you think the 3-minute video was slow, the actual original took 45 years.
I know some of the bureaucracy and economics that go into infrastructure today, but I feel like the decision to commit to a 45 year bridge must've been a whole different consideration for them back then. But then again, they spent much labor and resources creating tombs like the Pyramids.
Maybe projects like that are way easier to stomach when people stick around? The lord who ordered its construction or his son will preside the entire time, and I would imagine the builders would be building it until they retire or finish it. Any modern 45 year old project would probably have every job position involved in it (including, I would imagine, whoever was financing it) change people multiple times
Can you imagine it in an agile world? The value was being delivered by the ferries the whole time.
How about the cathedrals that are scattered across Europe? Some took centuries. People worked on them their whole lives knowing they’d never see the end result. Compared to that, a 45-year bridge seems quick and practical.
Sagrada Família, begun in 1882, is not planned to be complete until 2032.ília

Washington National Cathedral was completed over 83 years, 1907--1990.

There was an article about that recently, focusing on St John the Divine in NYC (which has also been under construction for more than 100 years)[0]. The argument is basically that since, by their nature, cathedrals can be functional before their construction is complete, having a long-running construction process allows the design to be more responsive to the populace's changing needs.

Also, in a world where leaders lived and died based on the approval of a centralized papal authority, it's just good politics to be known as "that city that's constantly been building that huge cathedral".


That's a super interesting point -- today we live in structures that are built in ~weeks and designed in probably similar timeframe. Then you live with it for decades, flaws and all. The idea of decades+ of design input sounds really interesting. I wonder how much those cathedrals would have their design change as construction progressed. Very cool.
An 8,000,000:1 ratio,† for what it's worth.



† Roughly. Using GNU units: 45 years / 3 minutes = 7889231.5

Yeah, but I would not be sitting there watching it 45 years either.
I imagine even just driving those (wooden?) pylons at the beginning to create the drainage areas took years. Even modern powered devices take a good day or so to pound in a single pylon around here.
For me its the opposite, I prefer the youtube version. The gif was way too fast and had to pause it several times because I was like "Hang on! what happened at this step?"
Yes, the gif is more time-efficient. But I watched the slower video first, and I'm glad I did. While I received the same amount of information, I spent more time thinking about that information.
I've noticed that the latest trend on social networks is to have ultra-sped up mini-videos, I think because it's popular on Instagram or TikTok (or both?). It's as if our entire civilization had suddenly caught ADHD.

Frankly maybe I'm old school but I found the Youtube version a lot more palatable, I could understand what was going on much butter, take a few seconds to understand the how the contraptions worked. When I watch one of these shortened ultra-edited versions I feel like I'm holding by breath.

Yeah, I cannot stand the trend of sped-up videos. Especially those "life hack" ones where people fold their laundry super fast or that kind of thing. I want to take the time to ingest what I'm seeing. If it's only enjoyable/watchable at 4x speed, maybe it's not worth paying attention to to begin with?

Of course time-lapses and stuff like that are intentionally sped up, but for something like an instructional video, it's going to be challenging to take real meaning from it.

In general it seems that people want to see some "neat" thing, click Like, and move onto the next interesting thing. For me, I don't relate. I like to dive into my interests and invest some real time into them. Otherwise my perception of the world and the things around me is super shallow. In fact, when I want information, I usually want text and images, not video/audio.

Further, I don't find it very rewarding to watch those sort of "clickbait" clips. I understand it can be satisfying in the short term, but I find almost zero need for this type of entertainment. I sense the primal nature of it and find it unappealing. I also feel that those primal "entertainment" desires are being exploited for clicks/likes/advertising, and I prefer to be compensated by greater value than relatively-shallow time-wasting if I am being exploited :)

Watched both, and it was clearer to me to go through the sped up version three times than watching the whole 3 min on youtube.

Most of us are used to faster paced information delivery, and we still go back to what we missed or want to check more in detail.

That’s what we deal with day in day out, and I don’t think we end up with an understanding that is shallower than when stopping at each frame for 5 seconds.

I find it sad it becomes some “kids these days” rant material when it’s just a matter of preferred watching pace.

The case study of the ADHD trend in general population is Mission Impossible IV. It is filmed by shoulder cameras and the mounter is just playing piano on the console: there isn’t a shot longer than 4s in the entire movie, and the average of changing camera angle is 0,7s. All you can get is an impression of the main character on any given image, but you can’t rest and you can’t contemplate. This is especially comical in romantic scenes because it makes you wonder how they came up with this idea of fast-paced romantic dialogues. Compare that to pre-2000 movies, even The Gremlins is ultra-slow and makes you wonder whether we were actually slow-minded pre-2000.
Alfred Hitchcock films would be agony to that crowd. The opening shot for his film "Rope" clocks in at about 9 and a half minutes. All in a single shot!
Opening shot? That movie only had one shot ;)
Several shots, planned out carefully so it could be edited to look like one shot.

Russian Ark (2002) (Russian: Русский ковчег) is a single 96-minute steadicam shot, and it has over 2,000 actors and three orchestras in it. It was recorded directly to a hard drive carried behind the camera operator, which could hold 100 minutes.

thus the winking emoji. thank you for reminding me that I need to watch Russian Ark again though!
And then watch the 'making of'. Also fascinating.
It was shot in segments but edited to look like one shot.

Back then, there were no such studio cameras to continuously record to film reels over a certain length.

The film camera magazine had a capacity of up to 10 minutes, so Hitchcock could film the scene all in one shot.
I honestly don't think it makes a good case study to be honest. Assuming what you say is true, I would still chalk up the shots/cuts to the artistic direction of the director/crew over anything to do with ADHD.

I think this falls apart even more when you compare Ghost Protocol to the most recent MI film, Fallout, which is the highest rated and grossing MI movie in the series. Just from an artistic perspective, it's shot very differently than Ghost Protocol.

I think this is an exaggeration. Short/Long takes are an artistic decision. We have recent movies that are a few long takes (sometime pretending to be a single take) 1917, Birdman, Russian Ark (true single take) all shot in recent years. Same with TV: True Detective has a famous long take scene, Mr. Robot, BCS.
A little cheer for Russian Ark. I liked it. Done as said, in one take.

Spot the bit well into the film where the guy nearly drops the book, you can feel the oncoming-but-narrowly-averted pain.

> there isn’t a shot longer than 4s in the entire movie

is this hyperbole? Genuinely asking.

- The pictures they make these days are all MTV. Cut, cut, cut, cut. The opening shot of Welles's Touch of Evil was six and a half minutes long.

- Six and a half minutes?

- Three or four, anyway

Probably one of the most well-known long takes. I don't think they're entirely missing from cinematography these days. Fukunaga's long take in True Detective is a great example.

Drone cameras actually help with this, you don't need space for a dolly or crane. A recent example would be Beyonce's Black is King.

Parent here. I admit this wasn’t from a scientific method, it is just that when I saw it in the theater, I suddenly understood why it was annoying, and started counting from there. Maybe there were longer shots earlier in the movie (although I’ve tried watching it recently and the first scenes were cut this way), maybe the average isn’t 0.7 which was a ballpark figure based on my counting.

Sorry for being probably wrong on the exactness of the figures, I thought the background idea was important, that pre-2000 movies were slower, and there has been an acceleration to the point of ridicule, and it is probable that directors dialled down from the extremely-fast-paced style because it didn’t find its audience. Yes, more recent movies didn’t go faster than that one, it was really a style that had its apogee in that movie.

Seems like hyperbole. I just looked at Mission Impossible Ghost Protocol (aka Mission Impossible IV).

In the first two minutes there were multiple shots of over 10 seconds.

And at the 0:14:44 mark there is a 24 second shot.

> The case study of the ADHD trend in general population is Mission Impossible IV. It is filmed by shoulder cameras and the mounter is just playing piano on the console: there isn’t a shot longer than 4s in the entire movie, and the average of changing camera angle is 0,7s.

Seems like hyperbole. I just looked at Mission Impossible Ghost Protocol (aka Mission Impossible IV).

In the first two minutes there were multiple shots of over 10 seconds.

And at the 0:14:44 mark there is a 24 second shot.

Here is the video source [0].

Its description says

"3D graphics and post-production: Tomáš Mustlek

Professional cooperation: Ing. Arch. Ondřej Šefců Graphic cooperation: Mgr. Zdeněk Mazač

More information about Charles Bridge can be found at

The digital model "Charles Bridge - construction of a pillar and vault field in the 14th century" was created for the project of the virtual exhibition Prague of the Time of Charles IV. The project is supported by the Ministry of Foreign Affairs of the Czech Republic as part of the National Celebrations of the 700th Anniversary of the Birth of Emperor Charles IV and is included in the AV21 Strategy programme."



Ok, we've changed to the video from Thanks!
Another video showing dioramas and construction techniques, from Muzeum Karlova most and other sources.

There is a lot more information in this article (in Czech, but there are pictures)

Dec 28, 2019 · 1 points, 0 comments · submitted by xkriva11
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