In 1647, a French mathematician named Blaise Pascal discovered that the pressure applied to any part of enclosed liquid would be transmitted equally in all directions through the liquid. Today, this is now called Pascal's Law.
While this law has shaped the very foundation of our modern view of fluid power, there were many more innovations before his time that have helped make the industry what it is today.
Every Wednesday, we share with you a look at these discoveries in our social media and for this blog entry we wanted to dive into the topic of Ancient Hydraulics even further. In this article we are going to look at some of the greatest feats of ancient hydraulics in history, and how these early cultures utilized them.
Mesopotamia and Egypt
Over 5000 years ago, the first civilizations developed around rivers such as the Mesopotamians and ancient Egyptians. The Mesopotamians developed on the Tigris and Euphrates River, and the Egyptians on the Nile. Because of this, water provided a major resource and tool to these early civilizations.
In Mesopotamia, the early farmers used a matrix of channels to direct collected water towards crops to keep their plants regularly watered through growing season. The ancient Egyptians on the other hand developed water irrigation a little differently. They practiced a system now known "basin irrigation" that used the flooding of the Nile to fill plot points until the fertile sediment settled and then return the water to its original watercourse. While both civilizations used a forms of irrigation, they also employed uses of other fluid mechanics.
One such is the water clock. A water clock is any time-measuring device by which time is measured by the regulated flow of liquid into/out-from a vessel, which is where the liquid is then measured. The Egyptians used a simple system of vessels with a sloping side that poured water at a constant drip through a small hole in the bottom. In Mesopotamia, they had a very similar version of water clocks but it measured the weight of the water flowing through the object instead of the level.
During the first millennium, the Persian Empire constructed elaborate tunnels into the basins of mountains for extracting groundwater. Shafts were dug vertically down throughout the tunnel on the slope of the mountain to collect and be directed out through the tunnel into channels that would distribute water in surrounding fields for irrigation. Because of this, the early Persian farmers were extremely successful despite long dry periods when there was no surface water available. These complex irrigation systems were referred to as qanats. And while the qanat was an incredible accomplishment that led to a greater hydraulics understanding, it was far from the most advanced one, which was even older!
Perhaps one of the greatest technological feats of the early Persian civilization was the Shushtar Historical Hydraulic System. This highly complex system has been referred to as "a masterpiece of creative genius" and declared a world heritage site by UNESCO (United Nations Educational, Scientific, and Cultural Organization). This historical site is probably best described as a hydraulic super factory! Its infrastructure is made up of watermills, dams, tunnels, canals, pools, and waterfalls and at one time powered up to 40 watermills in the surrounding area. What makes Shushtar so advanced and unique was that several cultures have helped advance it through out the ages from the early Persians, Romans, all the way back to Darius The Great, an Achaemenian king of Iran. This remains to be seen as one of the greatest exchanges of hydraulic engineering and its application throughout antiquity.
Ancient China relied heavily on waterpower and one of the best examples of this was the water wheel. In 31 AD, the engineer named Tu Shih invented a water-powered reciprocator for the casting of iron that was used to power the billows of smelters and casters. Waterwheels were also used to operate trip hammers for hauling rice and crushing ore. But perhaps one of the most extraordinary uses of the waterwheel in ancient China was from Zhang Heng (78–139 AD).
Zhang Heng is the first person known to have applied hydraulic motive power (i.e. by employing a waterwheel and clepsydra, or water clock) to rotate an armillary sphere — an astronomical instrument representing the celestial sphere. The sphere itself was rotated by a turning waterwheel, which in turn was powered by the constant pressure from the head of water in a water clock tank.The armillary sphere was perhaps the most important type of astronomical instrument in ancient China.
Today around 15,000 dams come together with thousands of man-made lakes, providing the small island country of Sri Lanka around 10,000 water tank reservoirs. But this massive, complex irrigation and water supply system can be traced all the way back to 300 BC! The first water tanks were invented during the reign of King Bandukabhaya who ruled from 437 to 367 BC. And even to this day, the advanced system is still being used.
Since early times, rice has remained a staple to the culture of Sri Lanka. In fact, rice occupies over 34% of their cultivation and approximately 1.8 million families island-wide are engaged in paddy cultivation. Because this food is so common and widely used, it requires cultivating year around. The only problem is the majority of the country's rainfall is in short spells of high precipitation. With the use of the island's natural water resources, this ancient culture has solved this issue for over 10,000 years with the use of of their highly intricate irrigation system. Although, from time time, the system does require some maintenance and renovation, it stands today as one of the worlds greatest hydraulic achievements.
While the great Greco-Roman times gave us some of the most captivating mythology, it also gave us some of the greatest hydraulic innovations in history.
The earliest evidence of a water-driven wheel is the Pearchora Wheel which was invented in Ancient Greece around 3rd century BC. It consisted of a large perpendicular wheel, bearing bronze or clay containers, which rotated with the help of animals through two wooden cogwheels that were vertically connected. The containers filled with water at the lower end of the wheel and subsequently tipped over to a tailrace at the higher point of the conduit. This great mechanism brought us "the water wheel" that we now know today.
The Roman empire brought an entirely different set of hydraulic achievements such as its impressive use of towering aqueducts, power using watermills, hydraulic mining, and providing public water supplies. But one of the greatest innovations the Romans developed was their sanitation system. Famous for public baths and latrines with complex engineering, the Romans were also known for their use of covered drains for stormwater and sewage. Some houses were even discovered to be connected directly to the drainage system. Even today, a lot of these ancient plumbing systems still remain intact, despite corrosion and other damages.
Throughout time, some of the greatest achievements of engineering can be attributed to our curiosity of the power in fluids. Each era has brought innovations that still provide these hydraulic solutions such as watermills, water wheels, plumbing and sewage, irrigation and more. Modern hydroelectric dams still use the power of flowing water to create electric power via turbines. Even Sri Lanka is still using much of the system that it developed 10 millenniums ago. Thanks to our rich history of fluid power and the engineering contributions of our ancient ancestors, we live in a world where hydraulic power is involved our everyday life, and will be for years to come.
If you enjoyed this article, and would love to learn more of the rich history of fluid power, we encourage you to check out our social media every Wednesday for our #waybackwednesday article. Each week we look at ancient and antique examples of hydraulics and pneumatics. Some of these posts feature technology that is hundreds to thousands of years old. Make sure to head over to our Twitter or Facebook each week to find out what else we uncover!