V is for Valve

Indoor plumbing doesn’t get enough credit. We take it for granted, but one night spent camping is always enough for me to write fan letters to my en suite bathroom at home. In fact, plumbing as a whole doesn’t get enough credit. Prehistorians love to wax lyrical about the plow or cave paintings or Platonic ideals. They should be talking about irrigation. After all, find a sizeable population in history, and you’ll probably find a valve.

The Romans kind of cornered the historical air time on valves since they were the gold standard (Bronze standard? it’s the Bronze Age…) for plumbing as well as central heating. Numerous articles cover this in Valve magazine, and yes, there’s a magazine dedicated to valves. However, while we should give the Romans their due, the Egyptians were the first to use valves in irrigation, the Indus Valley builders of the largest public baths, the Mesopotamians creators of one fabulous desert garden after another, and the Incans masters of harnessing gravity to create waterfalls and canals.

Harnessing the power of water was one of humanity’s first ways of controlling their environment. The valve was an integral part of the story, such a simple little thing but very powerful. The best inventions are. Let’s consider:

1. What is a valve?
2. When and where were valves first introduced in ancient civilizations?
3. What does the creation of the valve and the control of water imply about human thinking?

  

Diverting the Big Water

A valve is a stoppage mechanism applied to a flow of water. As water flows through a pipe, or any kind of waterway, a valve can turn the flow on and off. That doesn’t sound like much because we take turning tap faucets on and off for granted. However, anyone who has ever had a leak knows the panic that ensues if the water can’t be stopped.

Modern faucets typically use either a ball valve or screw valve, something where opening the flow rotates a hole from covered to uncovered. The hole can be manipulated with a single handle that moves up and down, sideways, or in a circle; it really doesn’t matter. The goal of a valve handle is to move the opening to the water or away from the water.

The earliest known large-scale users of water diversion techniques were the Egyptians, who slowly but surely irrigated crops by diverting the Nile. They constructed calendars 5000 years ago to track the timing of the annual floods (see letter “C”) and dug trenches to take advantage. It’s thought that those who irrigated with rising river water were probably the first to notice how natural valves worked.

If a tree fell across the river–not the entire Nile, of course, but a tributary or trench–it would block the water’s flow. This was nature’s dam, and early humans could easily watch and learn. They could create their own dams and diversions with those same trees or stones. Large objects were not easy to manipulate, but smaller ones could be placed or removed to control water.

Over time, a simple tree turned into a gate. The earliest gate valves were shaped constructions of wood, shaped to fit the canal. With the development of better building materials of wood and stone, the canals themselves were more solid and predictable formed. If you can build a stone tower and city, examples of which date back to 10,000 BCE (Göbekli Tepe), then you can shape the stone for a bath or a waterway.

The Power of Water in the Desert

One of the oldest and largest public sources of water is, in fact, a bath complex in modern Pakistan, called Mohenjo-daro. Today, it lies squarely in desert land, although 5000 years ago, the Indus Valley received more rain. But it was still a monsoon climate, which, like the Nile, happened periodically and with ferocity. To tame rainwaters like that requires ingenuity. The complex at Mohenjo-daro consisted of more than 700 wells, far more than in other early cultures, and a series of structures to divert the rainwater to one place: the Great Bath.

The Great Bath complex was built @2600 BCE as “the earliest public water tank” in history. It holds nearly 45,000 gallons (160,000 liters) of collected and diverted water. Gypsum plaster made the floor watertight. Researchers believe that this water was used for sacred bathing, tied to religious purification rituals. It’s another demonstration of how far ancient cultures would go to make water accessible when, where, and how they wanted.

When I was discussing the earliest uses of ice (“Ice Cream”), I mentioned that the Mesopotamian king Shulgi may have built the first icehouse, around 2000 BCE. The semi-arid and arid cultures of Mesopotamia–Persia, Babylon, Assyria, Akkadia–thrived in an area fed by the two rivers, Tigris and Euphrates. But the climate was still challenging.

Cyrus the Great built a major city at Pasagardae, now on a central plateau of Iran. There was rainfall, but it was not plentiful, and the climate was generally dry. Yet Cyrus built an extensive, sprawling garden. As I wrote in an earlier post on “Gardens of Power,” he did so to demonstrate the might of his kingdom over rival leaders. Why have a shallow, 10,000 m pond an inch deep? To demonstrate the engineering and labor that he could command. Look upon my trapezoidal ponds, ye mighty, and despair!

In Babylon, the ancient wonder of Hanging Gardens was built around 600 BCE as well. These gardens, perhaps created by one of the Nebuchadnezzars, had multiple terraces. Water was raised up from the desert climb, from waterways constructed to divert the flow to the gardens. An extensive system of canals combined with a new Mediterranean technique–the water-raising screw–could move the water from faraway rivers and mountains to the garden source.

The Archimedes screw was attributed to Archimedes, although he described it rather than inventing it. In 236 BCE, on a trip to Egypt, he noticed this large circular mechanism with grooves in it dipped into a waterway. As the grooves turned, water could pulled up and directed to a higher level. Eventually, the screw was given the special designation of being one of the seven simple machines. The valve is not, despite its importance in plumbing history, which means irrigation history, which means feeding populations history. I think it’s because the valve wasn’t invented by anyone Greek.

The city of Susa, or Shushtar, one of the farthest eastern Mesopotamian cities, was another triumph of water engineering. It employed what’s now called the Shuster Hydraulic System that had a series of diverted waterways from the Karun River to feed the city. The water might come in hard, so valves allowed the Sassanian engineers to regulate the water levels in the canals. Valves would prevent damage to the masonry during the heavy flow times and allow the maximum into the public reservoirs when the flow slowed to a trickle.

Overall, these examples from ancient arid or semi-arid climates show that the cultures built extensive gardens and baths, 3000-500 BCE, way before the Romans flexed their plumbing muscles. Growing cities used masonry, not just for buildings, but for water capture, diversion, and wastewater flow as well.

The Triumph of the Vulva–Er–Valve

Merriam-Webster tells me that the word valve comes from the Latin word for a folding door, perhaps from volver, to rotate. It also so happens that the Latin word vulva, which means the female folding body part that covers the tiny portal through which babies emerge, may also have come from volver. They aren’t sure. Might we not conclude instead that the Latin word valve may have been related to vulva? I’m just saying. It’s a folding door.

Anyway. The Romans get the main credit for inventing the valve because their bronze valves can still be found. Whatever the Achaemenids, Sassanians, Egyptians, and Persians were using for valves in 500 BCE no longer exists. Hanging Gardens, not there. They’re not even quite sure where they were, so we can’t credit old Nebuchadnezzar’s engineers, whose valves did not survive the test of time. Several valves did survive, many from Pompeii, which was very helpful in preserving material for archaeologists, though not so helpful to the residents who were there when–BOOM!

The hydraulic valves used by the Romans throughout their Mediterranean empire followed a style very similar to modern small pipe valves. These were made of bronze and known as plug valves. The top part would turn a cylinder in the middle that had a hole to open and close water flow. Note that the valves did not “screw” on to pipes because that design would have been too complex to build–these were blacksmiths, after all. Instead, the pipe is tapered. The small end fits into the large end fairly tightly to minimize leakage.

Valves also had another purpose that should not be skipped over. The Romans also used what was called a check flow or backwash valve. The valve could be built so that water would push it open in one direction, but keep it closed when flowing the other way. This is an important step in keeping wastewater from coming back out and contaminating the clean water supply.

Roman valves, pipes, and canals were built throughout their empire. By 300 CE, this included most of Europe, England, Persia, and northern Africa. Aqueducts left over from the Roman empire still stand over numerous sites, their construction solid enough to last for dozens of centuries. The same thing can be seen with Roman roadways, too, still threaded all over the empire. Like the roadways, this broad extension of Roman engineering across so much territory meant one more thing: standardization. They put their stamp on control of their environment, then made that environment really big. It left their engineering knowledge available to those who might want to use it.

Making Water Dance in the Andes

One more example of “ancient” hydraulic engineering is worthy of mention here. Technically, this doesn’t fit as well with the other examples because it belongs to the Incas in Peru, and their civilization’s height was later in time. We’re talking late Middle Ages, from 1300-1500 CE.

But, to be fair, they had limited contact with everybody else–the odd traveler who made it across either the Pacific or the Panama isthmus. The site of their masterpiece is called Tipón, another massive waterway complex similar to Pasagardae and Shushtar. Like their earlier Mesopotamian counterparts, the Incas used sophisticated techniques to divert water that ran down from the mountains. They didn’t use screws to move water upward, but they were masters at using the gravitational force of water to construct waterfalls where they wanted, split water into multiple streams only to have it rejoin in a central fountain.

The Incans bent water to their will, thus creating an impressive display that could be both practical and sacred, harnessing nature’s power for artistic and symbolic purposes.

Today, our more recent ancestors have constructed dams all over the place. If you have stood atop a large hydraulic “modern miracle,” such as Hoover Dam, you get that sensation of nature’s power and beauty, shaped to be at our command. A significant part of that power is now employed for electricity generation, as water power is far more eco-friendly than fossil fuels. Still, as climate change reorganizes the water system that feeds some of these dams, drying waterways may require a different solution.

We might need to learn how to use nature’s water rhythms better, to work with the changes in climate, rather than trying to bend nature to our will–and to our peril. There might yet be some knowledge in these ancient systems for us to glean. We just need to turn the valve that gets that ancient knowledge flowing to us.