this post was submitted on 02 Oct 2024
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How does that siphon work? I would think they would need a pump of some kind, even if it's just a bunch of Roman workers/slaves turning an Archimedes Screw, to get the water to go uphill.
Same way a fuel siphon works, as long as the opening is below the inlet, and the rest of the tube is full and sealed, the water will flow.
https://en.m.wikipedia.org/wiki/Siphon
How did the Romans seal that apparatus? Cement? Even that would fail rather quickly
Lead Pipes: http://www.romanaqueducts.info/siphons/siphons.htm
Also some terracotta pipes, but not really clear how its sealed.
It never would have occurred to me that siphons work that way, too!
By why did they even need one here though?
Because it's simpler to build siphons through large valleys instead of 100 meter high 10 kilometer long aqueducts.
But you have to keep water pressure throughout the length of that tube, how did they do that with their materials?
They had metal working and also knew how to work clay. Plus finding water leaks isn't difficult to know what specific points need attention, then you just add material until it stops leaking. The pipes might have been large enough to work from the inside if the flow was diverted.
They also wouldn't need a perfect seal, just a good enough seal that the majority of the water makes it to the other side.
I'd bet that there were teams of people whose full-time job was to maintain each of the siphons rather than the more modern approach of "build it and then bury it under asphalt because it will probably be fine for years" plumbing takes today.
For demonstration purposes only.
Valley was too deep for the aqueduct but they didn’t want to make the drawing taller just for that
Romans were notoriously averse to making drawings taller.
Yeah, but the water pipe goes back up meaning that there is near equal pressure on either side of the U-Siphon, right? Kind of negates the siphon, in a sense?
I'm no fluid dynamics expert. Just a casual Joe.
Its a bad diagram, the other side needs to be lower :/
The "pump" is the higher elevation at the source.
If you’ve ever used a siphon to drain a fish tank, it’s a similar concept. I believe the entrance is a bit higher than the exit, so I guess gravity and water pressure?
Not disagreeing with you there,, but if you've siphoned something you've probably done it with a polymer, how the heck were the Romans doing it? You can't get intestines sealed together tightly enough back in those days.
The Romans would often use lead or clay pipes with either dirt or concrete packed around them to make a solid seal that would resist the water pressure and not burst the pipe like a ripe fruit.
It needs to be water pressure because atmospheric pressure can’t lift water more than about 10 metres.