this post was submitted on 02 Oct 2024
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Illustrations of history

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[–] [email protected] 24 points 2 months ago (3 children)

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.

[–] CameronDev 43 points 2 months ago (4 children)

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

[–] [email protected] 7 points 2 months ago

It never would have occurred to me that siphons work that way, too!

[–] [email protected] 7 points 2 months ago (1 children)

How did the Romans seal that apparatus? Cement? Even that would fail rather quickly

[–] CameronDev 7 points 2 months ago

Lead Pipes: http://www.romanaqueducts.info/siphons/siphons.htm

Also some terracotta pipes, but not really clear how its sealed.

[–] [email protected] 2 points 2 months ago (3 children)

By why did they even need one here though?

[–] wischi 10 points 2 months ago* (last edited 2 months ago) (1 children)

Because it's simpler to build siphons through large valleys instead of 100 meter high 10 kilometer long aqueducts.

[–] [email protected] 4 points 2 months ago

But you have to keep water pressure throughout the length of that tube, how did they do that with their materials?

[–] [email protected] 8 points 2 months ago

For demonstration purposes only.

[–] tyler 4 points 2 months ago (1 children)

Valley was too deep for the aqueduct but they didn’t want to make the drawing taller just for that

[–] [email protected] 1 points 2 months ago

Romans were notoriously averse to making drawings taller.

[–] [email protected] 2 points 2 months ago (1 children)

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.

[–] CameronDev 5 points 2 months ago

Its a bad diagram, the other side needs to be lower :/

[–] [email protected] 15 points 2 months ago

The "pump" is the higher elevation at the source.

[–] [email protected] 14 points 2 months ago (2 children)

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?

[–] [email protected] 4 points 2 months ago (1 children)

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.

[–] [email protected] 8 points 2 months ago* (last edited 2 months ago)

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.

[–] [email protected] 3 points 2 months ago

It needs to be water pressure because atmospheric pressure can’t lift water more than about 10 metres.