A 2D Heron's Fountain Behaves Weirdly 

The object itself is 3D of course, but there's nothing interesting happening in one of those dimensions! What I'm saying is, there's a legitimate sense in which the mechanism is 2D. Don't @ me. The sponsor is CuriosityStream: Get a whole year for just $12 by going to curiositystream.com/stevemould and using the promo code stevemould at checkout.

"The turd on the shelf", precisely the kind of insightful and intellectually stimulating content we come here for. Keep up the good work!

You heard it here first folks: "Gas is less dense than air" 8:24 (edit: corrected time)

I feel like this would've been very cool to see with two different density fluids. Say water and mercury. We would be able to see a fountain effect without any air.

I remember seeing (and using) the German toilets when I went on tour there with a band in 1984. The sound engineer's theory was that it reduces the incidence of piles because people spend less time on the toilet (find somewhere else to read the paper) and the vocalist's theory was that it was so that you could look at what you had produced and have a greater chance of finding any indicators of bowel cancer (or other disease) there - they eat a lot of meat there. I also recall the same feeling of horror that you did when you see the fill-up-then-empty type. So, what to take away from this comment? If you want to see the toilets of the world, join a band and tour ;-)

The "Turd on the shelf" is especially helpful in the medical sector. Its easier to control the stool for blood or something or to get stool samples. But why people (like my parents) decide to install it in their homes is a mystery to me.

Oh look it's Derek!

Definitely wasn’t expecting a 2 minute lecture on different kind of toilet bowls 🤣

I have built many Heron's fountains, for my children and for my students, using bottles. But I always much separated (a quarter or half a metre) the two bottom bottles, used long pipes with long visible lengths outside them, and topped the top end of the uppermost pipe with a strainer. Results: • The fountain had a surprisingly tall jet, reaching very high over the pile. • Water circulation through the pipes was very visible, at least if some air bubbles were present. Once the top pile is empty of water, just putting the artefact upside down empties the bottom bottle into the upper one, and the fountain is ready to work again once returned to its normal attitude.

8:24 "Because gas is denser than air" I mean, you're technically right, sometimes...

“Gas is less dense than air” That had me laughing

this is so interesting!!! the 2d model really helped me understand what was going on, i really appreciate your effort into making this, i can't imagine how much thought it goes behind it. thank you for this video!!

1:36 We had that one in our apartment in Bulgaria, but sadly our cousin broke something in the mechanism, and we had to replace the whole thing with a "normal" (UK or US, idk) toilet bowl. Fills me with nostalgia when I see this old design. Never thought I'd cry over a toilet bowl...

I love that you even made a 1 dimensional demonstration for completions sake

I’d love to see a coffee percolator get the “2D” treatment.

You know, I actually really appreciate the brief toilet primer. It's always nice to know how one's things work.

I can’t watch this in HD, the eyes are too steely blue and seeing into my soul.

1:50 We would call it a "prestatiepot" at home, Dutch for "pot to show your achievement"

8:13 Steve Mould, professional U-tuber.

I wonder if this could be done with some sort of vegetable oil in place of the air, since it's about density

Great video! Personally I would love to see a visualization of a waterhammer pressure wave. We often see the effects of them, but I don't believe I have ever seen someone visualize it well

Ah, fluids. That subject which makes you remember air and void are two different beasts. (Because when you study rigid body mechanics and the likes, you consider everything to happen in a void)

I imagine filling that tube with an almost perfect 1/2 water, 1/4 air, 1/4 water took more time and effort than building the 2d heron fountain.

this is my first video of yours and the bell siphon is definitely how my bong works

Man, this channel and Your knowledge, accent, pure passion...its is all magnificent. Makes me look at the world in not-so-simple way but at the same time, a real way of how it works. Much obliged, sir.

“Let’s make a U shaped tube” Maybe we should call it a RU-vid?

These visualisations and explanations are just fantastic. Keep them coming.

Steve. The more I watch your videos, the more I think you want to achieve (or are obsessed with) perpetual motion :D

the detail about tubes in the middle partitioning something in half reminded me of the brilliant novel "The Planiverse" about a world entirely 2D and how things would need to be constructed to allow such a thing to work

I remember seeing one of those crazy toilets with a platform when i was travelling around europe 10 years ago. I called it the poop deck

In Germany, a young lady told me the poo-on-a-shelf toilet became common 'way back in the day because of parasites; people had to frequently check their stool to know if they were worm-free.

Buenisimo! me encanto tu fontana de Heron en 2D, se entiende perfecto su funcionamiento y es muy inspiradora para ver como poder mejorarla. Saludos.

Uk usually aligns with Australia RE plumbing supplies, we have flushomatics if you want to go into some hydrodynamics seen in our toilets. They seemed cool to me, but it was part of my carrer, so that might have helped. Basically the valve breaks an air lock which alows a certain amount of water to pass and flush the toilet, then the airlocked equilibrium comes back and the flow stops again, giving you a flush that doesnt need time to refill between uses, which is ideal for public toilets. The valves are also mostly recyclable, the seals will need changing every so many years, but basically its a similar system to gas bottles, you trade an old leaking one for a refurbished valve, they refurbish yours and trade it on to someone else, you dont pay for a whole new valve, and the majority of it lasts decades before actually becoming waste.

I read "2D heroin fountain behaves weirdly"... I need to sort myself out.

7:46 Let’s all appreciate how he was able to get half air half liquid in the left column of that tube. Edit: I’ve added a timestamp.

Have you ever done a video on the continuous cycle absorption system for refrigeration? It is used in a lot of RV refrigerators. A little pilot light can drive a beautiful combination of fluid dynamics and thermodynamics in one system.

I live in the Netherlands, and I never knew there were other toilets than these “turd shelve” types. Then I took a look at my own toilet and noticed it doesn’t even have a turd shelve. Conclusion: I never really paid much attention to toiletbowl layouts.

The shelf is there So you can appreciate your masterpice in full glory when you're done.

Wish i had found this video sometime in school so I could explain what you have in this video as a science project of some kind.

1:50 Washout toilets are used in the UK, too: That shelf is considerably easier to remove a stool sample from than most other designs, and (at least when I worked in the industry in the late 90s) they were common for hospital use, and also in 318 stainless steel; By order of HMPS. The greater distance through the trap also made it harder to use the u-bend to store stuff out of sight of staff, though there were other ways this was avoided.

"The turd on the shelf". i've only ever known it as "Kacketeller", which would roghly translate to "poop plate" :D

"The type of wire that's in your walls" is dangerously similar to the whole toilet situation. I'm convinced that World War 3 will start when someone asks an American, British and German electrician to wire up a house together.

This man's videos are in top-notch quality and it's so much educational yet super enjoyable!

I chuckled sensibly about "The Dribble!" Thank you for sharing, and stay safe.

I really like the way you transformed yourself into a polistiren cube for the demonstrations with the tubes

I saw this as “Heroin Fountain” and I was like “How the hell is this still on RU-vid!?

this was actually quite trivial. thanks to you, i can feel smart now and my self esteem is raised.

This is really my favorite series on RU-vid tbh

8:25 “gas is less dense than air” I guess you learn something new everyday

"gas is less dense than air" should be "air is less dense than water"

I really love watching this kind of videos during sleeping time

My Dad, a plumber of 40 years' 2 laws of plumbing. 1. Shit always rolls downhill. 2. Water finds its own level.

I grew up with a "turd on a shelf" style toilet and when I moved to America, dealing with splashes was such a shock

As I’m sure you can imagine, the rising of the water in toilets can be quite scary in the US as well if it doesn’t go back down

You simplifying it down to a single tube was impressive. It intuitively makes sense but would be hard for most people to conceptualize in that way.

7:46 That is marvelous part of your video. I managed to grasp how coil pump works. Thanks:-)

[Looks at toilet designs] OH!!! So *thats* why every other country in the world always gets "floaters" and I've never had a problem.

I grew up with the WTF toilet. I'm from Germany and I always assumed it was normal as a kid. Until eventually I got into school and visited other kids and realized that our toilet was kind of unique...

I wanted to know this since a decade and finally got the chance now in the best way!!

I never knew I wanted to know how a herons fountain worked, until 3am on this fine morning

the "turd on a shelf" toilet was invented by Germany. as a German, I think this is the second worst thing we have ever done.

I've moved to the Netherlands and the first time I encountered the poo on a shelf style toilet my first reaction was indeed: WTF... I have my own name for them though, I call them inspection shelf toilets.

Really interesting and top-notch presentation.

This really makes me want to see one where a greedy cup mechanism empties the bottom container when its done so you can reuse the water to refill the top and start it over. I think might work if the base water level at the bottom seals off the air from escaping into the greedy cup mechanism

I'll admit, as interesting as this was, I was expecting a lot more when I read the title as "Heroin fountain"

It would be interesting to see with two liquids of different densities ie water and oil

Design note- you may want to use less right angles on your drains, both for this and for the 2d Greedy Cup. Love your stuff.

Well darn it I was looking for a way to make my own Perpetual Fountain watched about a million herons Fountain videos not a one of them said that it didn't keep running. You're the only one that mentioned that it would stop after a while

"Turd on the shelf" Or as I like to call it, a poo with a view.

Steve: *Makes an amazing video* Everyone: 8:25 gAs iS leSs deNse thAn aiR

Those labels on that chart showing different types of toilet mechanism are very accurate. Especially the 'wtf' at the top right of the chart. Exactly what i was thinking.

Brilliant explanation, bravo!

Everyone after watched the video : "wow, that's amazing. Now i understand physics" Me : "I want to drink that orange syrup"

Thanks so much very well illustrated.

You gave me an idea to use this principle for my cat's drinking fountain (cats love fresh, moving water). So I'll give you an idea for a video: Water locks with water saving basins. I'll refer you to look up how the Panama Channel water saving basins work. Water locks may be simple in principle, but Water is such an important resource for the Panama channel they invested billions into water saving basins that save up to 60% of the water used per crossing. Because if it rains too little or they use up too much water, the depth of the cannal may render it impassable for shipping. The way they work is that when a boat has to be lowered, instead of discharging the lock's water into the lower level of the waterway, it instead drains into a separate basin that is at a higher level than the lower channel. The water level at the lock and the basin will level off, at that point the valve between the lock and the basin is closed and the rest of the water has to drain into the lower level of the waterway. When a ship has to be raised, the water from the basin drains into the lock, then the basin valve is closed and the lock fills the rest of the way with water from the higher level. A one basin design can save roughly 20-25% of water (it depends on the area covered by the basin). Panama channel uses 3 basins per lock. each at one height. When one levels off, the valve closes and the next one gets filled and so on. It's a really simple and clever piece of engineering. And I've made one in Algodoo, so I can definitelly tell you it can be made as one of your models. Also, just for curiosity's sake, I calculated how much each cubic meter of water costs to be moved on the panama channel based on how much water is drained and the cost of traversing the whole thing. They charge $60 dollars per empty 20 foot container and $90 for each full container. The largest Panamax class ships can carry 15000 20 foot containers, so based on that, the height of the cannal and the size of the locks (there are six and they're all the same size), I calculated that each cubic meter of water in the panama channel costs between $0.16 and $0.25 if we don't take into acount the water saving or $0.40 to $0.60 if we do. Where I live, the cost per cubic meter of treated tap water is roughly $1.

I would have loved to see instead of air, oil or some other liquid that is less dense as water as an example to show it working, this is all very interesting stuff, keep up the good work

This reminds me of a Gitton`s water clock in my hometown in a shopping mall. i used to admire it for hours. very cool

In dorms we call old "turd shelf" toilets simply "the stage" xD

8:20 "Gas is less dense than air" - Steve Mould, 2020

The “shelved” toilet also helps for those who need to keep an eye on their health via their stool. Yes, really, certain health conditions can be tracked really well by checking the changes in how the stool looks.

The "turd on the shelf" one is horrific to me. It's kinda common here in Germany, but whenever I encounter one, I question the owner's mental stability... No, I DON'T need see my s**t in its full glory, thank you xD

When I used to visit Amsterdam for work and asked about the "poo shelf" in the toilet bowl I was told that it was because folks from the Netherlands like to eat lots of pig based products. Pig based products can be susceptible to worms, and so the shelf allows the poo-er to inspect their delivery for parasites.

It would be interesting to see this done with two liquids of different density. Of course, it would be very tricky to fill.

Cool! New subscriber. I've been looking for a clear explanation of these.

Reminds me of how I would play with my drinks as a kid. Taking a straw sticking it in a drink, closing it off, taking it out and flipping it around, switching the end you closed off, inserting it back in the drink and releasing your finger. The straw then creates a mini fountain that works similar to this fountain.

Despite never seeing or hearing this before, I immediately understood how it works the 2D version in the very beginning of the video, this is awesome work in making it so much easier to understand!

"Gas is less dense then air" 8:24

This was very interesting! Thank you!

It's fun that I think of my name as a really uncommon name but I see that Heron is a really well known math formula and that video's subject

The shelf is the old style, had to do with being able to inspect the stool to spot illness.

Super informative. Ive always wondered how they had fountains before electricity.

When i was an apprentice Plumber (55 years ago in the UK), we used to fit syphonic WC pans, quite often. They were far superior to wash-down pans.

4:46 nice book you've got there

With all the "gas is less dense than air" quotes in the comments, before someone else points it out, at 8:37 he meant "half column of liquid, half column of *air* on the right"

Ideas for hydrodynamic systems: shishi-odoshi (found in Japanese gardens), water drinking bird, ancient water clocks, fluid valves, the Panama canal.

I'd love to see some sort of device that sort of works like one of those birds that drinks water but a fountain that continuously pumps with solar heat. So the point would be you'd have something like your herons fountain 2d but then paint the surface black or something and let the solar power absorb the sunlight and pump the water. I assume there would have to be a temperature differential.

I want to see a design which chains several reservoirs together so you can change them out on a rotational basis and keep the fountain going without stopping (preferably while using the same water).

I’ve just retired from building and repairing CT and MRI scanners for 40 years…worked with everything from liquid helium and a variety of thermodynamics to high Tesla magnetic fields, High freq 150kv generators and a variety of radioactive isotopes. Only had 2 years of formal education, but I have always had a fascination with how shit works. I only discovered Steve here about 2 hrs ago on a chain fountain video, that took me to tensegrity, then to heron fountain and I’ve been thoroughly entertained and educated..Totally enjoying your explanations, theories, and demonstrations… thanks!! your kids are lucky to have a father like you, my dad is the one who provoked and nurtured my curiosity…. I liked and subscribed!! (And am making my friends watch your videos cause they are clueless..lol)

I am way too high to understand this I’ve been blankly staring at it this whole time- 10/10 video

At 10:20 you see a bubble entrained in the pressurizing column and the mechanism still works as water flows around the bubble. The bubble must slow the water flow and this is neat example of how entrapped air can mess up flow, as in some siphon systems. Overall, a nice visual demonstration of an unintuitive phenomenon.