Gentle Blotters– another site we need to add to our tour list is Pont du Gard. Magnificent arch structure used as an aqueduct near Nimes France. My spousal unit and I visited circa 1994. At that time, you could park in a lot, walk up a bunch of stairs and then physically walk through the aqueduct (crouching for me since it as less than 2m tall) from one end of the valley to another.
UC#3
¿Qué es un Acueducto?
An aqueduct is a watercourse constructed to carry water from a source to a distribution point far away. In modern engineering, the term aqueduct is used for any system of pipes, ditches, canals, tunnels, and other structures used for this purpose. The term aqueduct also often refers specifically to a bridge carrying an artificial watercourse. Aqueducts were used in ancient Greece, ancient Near East, and ancient Rome.
Underground aqueducts of Cantalloc, Nazca, Peru By Diego Delso, CC BY-SA 4.0
The simplest aqueducts are small ditches cut into the earth. Much larger channels may be used in modern aqueducts. Aqueducts sometimes run for some or all of their path through tunnels constructed underground. Modern aqueducts may also use pipelines. Historically, agricultural societies have constructed aqueducts to irrigate crops and supply large cities with drinking water.
Pont du Gard, in Vers-Pont-du-Gard, Gard department, South France. The Pont du Gard is the most famous part of the roman aqueduct which carried water from Uzès to Nîmes until roughly the 9th century when maintenance was abandoned. The monument is 49m high and now 275m long (it was 360m when intact) at its top. It’s the highest roman aqueduct, but also one of the best preserved (with the aqueduct of Segovia).
– By Benh LIEU SONG (Flickr) – Pont du Gard, CC BY-SA 3.0Wikipedia
Rise Over Run: The Incredible Engineering of the Roman Aqueducts
Vitruvius recommends a low gradient of not less than 1 in 4800 for the channel, presumably to prevent damage to the structure through erosion and water pressure. This value agrees well with the measured gradients of surviving masonry aqueducts. The gradient of the Pont du Gard is only 34 cm per km, descending only 17 m vertically in its entire length of 50 km (31 mi): it could transport up to 20,000 cubic metres a day.
According to Wikipedia: Construction cost: 30 million sesterces (est.)
Roman currency took a bouncy ride on the inflation train, with the metal in the coinage routinely debased. But let’s go with some rough estimates.
A loaf of bread cost roughly half a sestertius, and a sextarius (c. 0.5 L) of wine anywhere from less than half to more than one sestertius. One modius (6.67 kg) of wheat in 79 AD Pompeii cost seven sestertii, of rye three sestertii, a bucket two sestertii, a tunic fifteen sestertii, a donkey five hundred sestertii.
Hard to get an exact quote for the price of a donkey, but it seems to be around $500-$750.
Quora Donkey Fact:
They are very territorial and will fight coyotes if they enter the pasture. A 1000 lb horse will run from a group of coyotes, but a 150lb donkey will stand and fight. Coyotes tend to make a wide berth around pastures that have donkeys in them, because donkeys will kick the crap out of them. Donkeys, to coyotes, are the crazy guy you don’t want to hang around because he might kick your ass with no warning.
Let’s do some very rough estimates and say that a Sestertius at the time of the construction of the Pont du Gard aqueduct was $2.00 USD. That would put the construction cost at $60,000,000.
ChatGPT gave us the following estimate:
For a rough estimate, we can use the value of silver. In 40 AD, the value of silver was significantly different from today. But, based on historical data and estimations, we could roughly say that one sestertius (plural: sesterces) might have been equivalent to a few grams of silver.
Let’s assume, for example, that one sestertius might have been roughly equivalent to the value of 2 grams of silver. Then, 30 million sesterces would represent 60 million grams of silver.
Chat GPT
Today silver is selling for $0.90 / gram. That puts us very close at $54M – same ballpark as our original estimate.
Note: Astro-donkeys (not available to the Romans) are a big pricier.
UC#3’s Slideshow
UC#3 was kind enough to share his slideshow from his visit to Pont du Gard. Even back in c. 1995, he was promoting twine-based solutions to modern problems.
Gentle Blotters – as a former civil Engr and winner of the tongue-in-geekGolden Plumb Bob Award at college, I would say gravity is your friend and and even a 0.034% slope can work…
Another friend of mine also got the Plumb Bob award and we having a celebration at a local pub, He suggested we not sit together similar to how they don’t let the US VP and President fly on the same plane in case there is an attack.
And, by the way, the Golden Plumb Bob award has disappeared off our mantle. I suspect my spousal unit moved it since it didn’t fit with our decor.
And to add to the list of adages, in the oilfield they say ‘there ain’t nothing you can’t fix with duct tape and baling wire’.
UC#3
He encountered a bit of stormy weather as late afternoon thunderstorms rolled through southern France.
Aqueducts: Not to be confuzzed with Aqua Ducks
Semi-Sequitur: Roman Aqueduct Engineer Saves the Day!
Want read a cool, exciting book about aqueducts? Such a book exists? Big Vesuvius YES.
All along the Mediterranean coast, the Roman empire’s richest citizens are relaxing in their luxurious villas, enjoying the last days of summer. The world’s largest navy lies peacefully at anchor in Misenum. The tourists are spending their money in the seaside resorts of Baiae, Herculaneum, and Pompeii.
But the carefree lifestyle and gorgeous weather belie an impending cataclysm, and only one man is worried. The young engineer Marcus Attilius Primus has just taken charge of the Aqua Augusta, the enormous aqueduct that brings fresh water to a quarter of a million people in nine towns around the Bay of Naples. His predecessor has disappeared. Springs are failing for the first time in generations. And now there is a crisis on the Augusta’ s 60-mile main line – somewhere to the north of Pompeii, on the slopes of Mount Vesuvius.
Attilius – decent, practical, and incorruptible – promises Pliny, the famous scholar who commands the navy, that he can repair the aqueduct before the reservoir runs dry. His plan is to travel to Pompeii and put together an expedition, then head out to the place where he believes the fault lies. But Pompeii proves to be a corrupt and violent town, and Attilius soon discovers that there are powerful forces at work – both natural and man-made – threatening to destroy him.
