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While the accuracy is impressive (the article here says altitude difference of a few millimeters when the tunnels met, but comments have pointed out that’s an error and it is actually a few decimeters), the really cool part to me is the techniques Eupalinos employed to make sure the tunnels connected even if there was significant error.
The diagrams in the article show how they changed the lateral direction of both tunnels to ensure they would collide in the horizontal plane, and expanded the ceiling of one tunnel and the floor of the other to ensure they would also intersect in the vertical plane. The diagrams in the article are illuminating, with some thought you can see it’s a very robust error correction mechanism that requires only a fraction more digging effort, and only requires precise measurements of the length of each tunnel (much easier to precisely measure than the angle or level!). Fascinating stuff.
The first tunnel of this kind is of interest also https://en.m.wikipedia.org/wiki/Siloam_tunnel
Another page about this kind of technology: https://en.wikipedia.org/wiki/Qanat
That taught me they had ice houses in Persia in 400 BCE (https://en.wikipedia.org/wiki/Yakhchāl)
> tunnel of 1,036 m (3,399 ft) length... built in the 6th century BC... excavated from both ends... At the rendezvous, the closing error in altitude for the two tunnels was a few millimetres.
starting a hole from two ends a kilometer apart and meeting within a few millimeters in any axis is phenomenal, would love to learn more about what they used to ensure this kind of accuracy
There’s a pretty significant section in the article called “Surveying techniques and construction” that answers your curiosity.
It's actually not in there, but in one of the sources quoted.
> 4 Techniques for measuring altitude : Altitude measurements seem to have been made with a chorobates, a primitive leveller with a vessel for water, or forerunners of this instrument. Eupalinos probably measured the south and independently the north entrances more than to check once his between results and to obtain a higher level of accuracy. He would have chosen a flat path around the mountain following a contour line not necessarily on the same level as the entrances. When the two parts meet in the tunnel after three km, the closing error of the levelling is small, only a few decimetres and the accuracy is still better at the entrances. Eupalinos had probably arranged two stone blocks at each entrance, with flat and levelled top surfaces, aligned with the tunnels, from which the level of the floor of the tunnel could be guided. Possibly a movable wooden pole was used to level it with the surface of the two outer stone blocks. Further into the tunnels lines on the walls seem to have taken over the role of the outer stones. Eupalinos himself seems to have expected a somewhat less precise result as he raised the ceiling of the north tunnel by 2.5 m and lowered the floor of the south tunnel by 0.6 m, when approaching the meeting point.
> the closing error of the levelling is small, only a few decimetres
I guess "millimeters" in the article is in error. Decimeters is much more believable.
I'm behind Tor, but anyone else in this comment thread could fix the Wikipedia article
It's outstanding how advanced the ancient Greeks were. What characteristics allowed their civilization to flourish so rapidly in science to the extent that they weren't matched in Europe until the Renaissance?
Deep, grounded answers are lacking because we don't have something like a theory of social/cultural evolution.
Many potential factors are clearly not relevant: was not a major population center like Egypt, was not particularly rich in resources, was not a serious military might like Persia (except, though, in maritime context), was not centralized (quarreling city-states). Economically it was based on slave labor like the entire region. It was an extrovert society (trading a lot, establishing seaside colonies all over the Med etc), but so were the Phoenicians.
Maybe in the end it was just a non-linear cascade that is hard to explain "linearly" after the fact. Maybe using their interactions to copy and cross-fertilize what all the pre-existing cultures had to offer created a domino effect where one thing led to another (eg. improved script -> better education -> smarter logistics -> more spare time -> more philosopher-scientists -> more mathematics, you get the picture).
Its equally important to understand what caused the eventual decline. The depressing fact that "progress" is not monotonic. Could we be heading toward a new middle ages?
It could be a selection effect too. The Greek world is unusually well-studied. This tunnel was discovered and excavated in the 1800s by German and French archaeologists.
It helps that the Greek world was close to Europe and has a large literary legacyy (partially because of continuity through Rome).
Compare that to ancient Mesoamerican or African or Indian civilizations, which have a relatively shorter period of intense study, but every decade we seem to come away more impressed.
For example, Nazca puquios are still a bit of a mystery but are extremely sophisticated tunnel and irrigation systems: https://en.m.wikipedia.org/wiki/Puquios
Currency, colonies, cultural coherency (shared language and festivals) along with massive internal competition. Militarily strong city states, within which verbal argumentation flourished. All that was prior to literacy, which hit around 750 BC.
Then one big thing was the development of a philosophical perspective that treated math as the basis of reality. That was also re-emerged as a trigger of the scientific revolution. Attributed to Pythagoras—but he deliberately never wrote anything down. What’s nice about not having written doctrines is that they can more easily evolve. The Pythagoreans, btw, also apparently conducted the first hypothesis driven experiment — testing their mathematical model of musical consonance by generalizing it from stringed instruments (where small integer ratios of string length produce consonance) to bronze chimes (where they found small integer ratios or chime thickness also produced consonance).
The recognition that “all is number” corresponds with (but doesn’t necessarily cause) big leaps in collective cultural progress.
Er, the Romans pretty much continued the science and engineering of the Greeks --the management of water alone was a massive engineering feat that wouldn't be matched for centuries. But mainly science and engineering was killed off by a cult that thought such things were against their beliefs and dogma. They were particularly successful in moving all literature and existing written studies to their cult offices or destroying them altogether. Eventually, the power of this cult waned a bit and science started flourishing again, a few centuries later.
One major input would be climate and resources. Much communication around the Mediterranean helped them. Saying "geography is destiny" is probably too strong, but the generally advanced cultures around the Med and Levant certainly played off of each other.
It was in this milieu that the philosopher Pythagoras received his mathematical education on Samos. The Temple of Hera had just been built — it was the largest stone temple in the world at that point. He would have been exposed to some of the most ambitious engineering communities in the world!
It is telling that in the early middle ages they apparently stopped clearing the tunnel, letting it silt up, similar to many large Roman buildings. Goes to show that the path of human history is not always one of progress.
Numberphile video about this tunnel:
https://youtu.be/kwrDX5qkwvA
I'm curious about this "silting up" described by the article. Was it preventable? Did it happen due to lack of maintenance?
Wikipedia mentions some of it was caused by a bad pipe at a location, but things like this https://www.youtube.com/watch?v=vLZElIYHmAI indicate that silting would occur naturally, and need to be controlled. It's quite advanced fluid dynamics and study to work out the variables so the flow doesn't drop silt or erode the channel.
Most natural caves in the UK are either silted up or stained with a natural pigment (peat, etc). Keeping water clear in a tunnel over the course of centuries without replacing the wall linings regularly would probably be hard if there's anywhere the silt or pigment could come from.
>The Eupalinian aqueduct was used as an aqueduct for 1100 years
What things today will be used for 1100 years?
The Panama and Suez canals are good candidates.
Assuming no AI takeover, massive technological increase, civilizational collapse due to dysgenics and lack of cheap energy, etc.
Even with all those things, the canals might still be used in 1,000 years. None of those things change the likely truth that floating physical goods is cheaper than land transport and those canals are at globally strategic points.
The AI will have to move goods, technology change will still need to move goods, civilisations will rise and fall and still need to move goods. Even if energy gets more expensive, trade will still occur.
For every point except AI takeover, I agree.
AI takeover isn't well defined, and by extension it isn't assured to be sensible — if a narrow AI is made to optimise the heck out of [high contagious, short latency period, long incubation period, high lethality, can form stable reservoirs in other species], it can be good at that without any long term planning about what happens next.
Conversely, we can also consider one that solves Von Neumann replication, and then it's less than a century to disassemble the planet Mercury, and from there a week or two for each of Venus and Earth. Assuming it had that as a goal.
In the tunnel category, maybe the tunnel under the English Channel, it's pretty impressive in its own right.
I wonder if anyone has done any studies on how many years it could stand unused without maintenance before some event would flood it.
Probably Perl, though it will continue to bring surprise to those who find it has been gluing their systems together.
imagemagick
SSH tunnels?
that is spectacular!