The Silver Mines of Hostotipaquillo Part 9 of 10: Ex-Hacienda Santo Tomás (the aqueduct and water wheel system)

Water cascades from the aqueduct sluice down into the waterwheel structure. A still-functioning aqueduct provides water to Hacienda Santo Tomás. The non-functioning waterwheel once powered machinery used in the silver refining process. Water was also necessary for the tequila production that, over time, replaced silver refining as the economic focus of the hacienda (see Part 8 of this series). Santo Tomás was not the only hacienda de beneficio (refinery) in the area that employed a waterwheel. Those who have been following this series will remember a similar arrangement at ex-Hacienda Mochitiltic (see Part 5).

In this posting I will show you the aqueduct and waterwheel and describe how they worked together. I'll also tell you a bit about the long history of waterwheels. Those wishing to visit ex-Hacienda Santo Tomás will find directions in Part 6 or you can use this interactive Google map.

The aqueduct

The aqueduct brings water from a source above and to the east of the hacienda. The two pillars are part of some ruined hacienda structures. Behind them, crossing the hillside, you can see the dark line of the aqueduct's wall. In order to reach this point, you need to walk down the street past the capilla (chapel) and take the right fork up the hill. You reach the point seen above near the end of the cobble stone street. From here, you need to scramble up the hillside to the aqueduct wall.

Access to water was essential at every hacienda. It kept livestock and crops alive, as well as providing for the needs of the human inhabitants. However, water was especially important on a hacienda de beneficio, where it provided power for the machinery in a time before electricity was harnessed. In order to do so, the water needed to originate from a source that was higher than the waterwheel in order to utilize the force of gravity. As a result, haciendas de beneficio--including Santo Tomás--were nearly always constructed in canyons or arroyos. 

The aqueduct still provides a steady stream of year-round water. The wall on the right is about 1 ft. (1/3m) wide and is walkable, if you have a sure sense of balance. However, you probably should not try this if you are not comfortable with it. The aqueduct continues around the bend in the hill. I was impressed by the quantity of water it carried in this arid region.

Aqueducts have been used for millennia by civilizations all over the world. Four thousand years ago, the ancient Minoans on Crete developed what may have been the first system of aqueducts for irrigation. In other places, aqueducts were used to transport water to support urban life. For example the ancient trading city of Petra (in modern Jordan) used a system of tunnels and channels carved from solid rock to provide water to their city.

Around the bend, the aqueduct heads toward the spillway structure. The spillway turns at a right angle from the aqueduct and drops its load of water several meters down into the waterwheel structure. As you can see, the hillside leading from the hacienda up to the aqueduct is pretty steep. The hill continues up to the left to where it meets the fence that lines the edge of the 15D cuota (toll road).

The Deccan civilization of India built some of the earliest aqueducts. One of them was 24km (15mi) long and, among other uses, supplied water to the royal baths. During the Iron Age, the people of Oman in Arabia used underground aqueducts constructed as "a series of well-like vertical shafts connected by gently sloping horizontal tunnels". One of the longest ancient aqueducts was built by the Assyrians (in modern Iraq). It was 80km (49.7mi) long and 10m (32.8ft) high where it crossed a 300m (984ft) wide valley.

The spillway juts out like the prow of an 18th century galleon. Just above the wall on the right, you can see the north wing of the casa grande. The adobe wall on either side of the spillway is the south part of the casco wall that surrounds and protects the main structures of the hacienda. The modern pueblo of Santo Tomás rises up the hill on the other side of the arroyo.

The Roman aqueducts are, of course, the most famous. Their water projects were built all over Europe, North Africa, and the Middle East. The various aqueducts feeding water to the city of Rome alone "totaled over 415km (258mi)...and set a standard of engineering that was not surpassed for a thousand years". 

This arch supports the spillway above. The view is to the west along the south casco wall. In the distance you can see a tall conical structure, which is one of the bastions that protect this side of the hacienda. There is another view of it in Part 6. One defect of the hacienda's defenses is the hill to the left which rises high enough that an enemy could look down into the courtyard inside the walls. Snipers in that high position could make movement difficult for the defenders.

Aqueducts were also present in pre-hispanic North and South America. Around 540 AD, the people who designed the famous Nazca lines in the Peruvian desert brought water to their communities with aqueducts that are still in use today. In Costa Rica, a unknown civilization of ancient people built another still-functioning system of aqueducts. Finally, when the Spanish arrived at the Aztec capital of Tenochtitlán (today's Mexico City), they discovered two large aqueducts to bring fresh water across the salty Lago de Texcoco to the island city. The Spanish conquered the city, in part, by destroying its aqueducts. 

The water wheel structure

Another view of the water spilling into the water wheel structure. The long pipe running diagonally across these structures is a 20th century addition to the water system. The lower arch in the upper left provided the view of the casco wall and bastion seen in the previous photo. The large arch just above the pipe is the opening for the axle of the water wheel, which extended out to power ore-grinding machinery on both sides . Above the large arch is a row of square holes. These are for rafters which once extended out to support the roof of a structure that sheltered the grinding machinery.

The origin of the water wheel is even more ancient than that of the aqueduct. The very first may have been the shaduf in Egypt. It was developed around 4000 BC--six thousand years ago! A shaduf has a lever with a weight on one end and a bucket on the other. It is used to lift water out of the Nile up to the bank and into an irrigation ditch. Shadufs are still in use along the Nile today. Like they say, if it ain't broke, don't fix it.

The waterwheel structure, viewed from the courtyard. The structure is approximately 50m (150 ft) long and 7m (21 ft) tall at the lower end. This waterwheel structure is much more complex than the one in my posting on ex-Hacienda Mochitiltic.

It was a long time before water wheels were used for anything but irrigation. People had been grinding grain using something called a quern stone since around 4000 BC. Around 500 BC, a rotary quern stone was developed as a way to grind grains using human or animal power to turn the stone. However, by 400 BC, a Greek had the bright idea of harnessing water to do the grinding, thus creating one of the first automated machines. Sometime between 200-100 BC, people began using horizontal water wheels ("Noria wheels") to turn the grindstone.

An arch was constructed in the wall in order to allow easy access to work areas. Two of our Hacienda Hunters can be seen in the courtyard through the arch, along with the portales of the casa grande in the distance. At this point in its base, the waterwheel structure is about 1.5m (4ft) thick.

Archeologists speculate that the idea of a horizontal wheel came from the widespread use of pottery wheels in the area around Sidon (on Lebanon's coast), which also has many mountain streams. In any case, a Greek from Sidon called Antipater wrote about Noria wheels in 100 BC. Previous to this, about 250 BC, other Greeks had developed gears made of wood. Not too long after the invention of the Noria wheel, someone else figured out that if you made the wheel vertical and used the previously-invented gears, the result was much more efficient than using un-geared horizontal wheels. 

Openings on either side allowed access to the slot within which the wheel moved. I am not sure of the purpose of these openings, but they may have provided a way to maintain and repair the wooden structure of the wheel. 

The first vertical water wheels were of the "undershot" type. This involved immersing the paddles of the wheel in the stream passing below, in order to push them and turn the wheel, which then turned a horizontal axle. The axle rotated the gears, transferring the energy to the vertical grinding quern. This was a great advance over the horizontal wheel, but the velocity of the water could vary according to wet or dry weather, reducing efficiency. Then the Romans got involved and created the "overshot" wheel, which drops the water onto the paddles from above at a controlled rate. The one at Santo Tomás was of this type.

Another access point in the structure. This one has a row of rafter holes above it. Jutting out from the wall, just below each hole, is a wooden nub which gave extra support to the rafters. Although the opening and the rafter holes are lined with brick, the overall structure is constructed with rough stone, covered with plaster.

The Roman invention of the overshot wheel occurred sometime in the 1st or 2nd century AD. The Chinese also developed an overshot wheel about this time and may have gotten the idea through trade with Rome. The overshot wheel was more expensive to build, since it usually required a dam to create a pond and a mill race to carry the water to the wheel. However, the increase in efficiency made up for the initial expense. The velocity of the water could be controlled and additional torque was produced from the weight of the water falling on the paddles. 

The arched opening at the base of the structure is the exit point for the water. Another aqueduct beginning at the opening carries away the water. The stone-lined ditch turns sharply to the right and continues down the hill past one of the buildings in the courtyard.

The ruins of a great Roman mill have been found in southern France near Arles. The mill used 16 water wheels, two abreast, in stair steps down a hill, to produce enough flour to feed 12,000 people. Over the following centuries, water wheels were used for many other purposes, including sawing wood, running bellows in forges, and pumping water out of mines. After the Middle Ages ended, water wheels became central to the birth of the industrial revolution. By the early 1900s, they were being used to produce electricity. And it all began with the shaduf, six thousand years ago.

The grinding disks

Several circular pits are located near where the waterwheel axle emerges from the wall. I took this telephoto shot from above, on the aqueduct spillway. During my second visit, I was as yet unable to gain access to the interior of the hacienda and so had to perch precariously on the aqueduct spillway to photograph what I could. I was somewhat mystified by the circles, but their proximity to the waterwheel structure strongly suggested a relationship.

View of the inside of a roofless room on the west side of the waterwheel structure. The opening in the wall is where the axle emerges on this side. Barely visible in the lower right is another of the circular pits. There were at least a dozen of the pits near the axle hole, with about half of them on each side of the wall, . The rafter holes above the axle hole show that this area, like the one on the other side, was also roofed at one time.

Full view of the circular pit seen in the previous photo. Each of the pits has a hole in its center. I finally concluded that these were the bases of grindstones, which had once been placed horizontally over each pit and turned on an axle projecting up from the center point. The grindstones themselves are long gone, along with the geared apparatus that turned them,  However, this must have been a complex mechanical operation, with the waterwheel providing the power to turn multiple grindstones simultaneously. 

The large chunks of ore were first broken up outside the mouths of the mines, usually by women and children. The smaller rocks that resulted would have been packed down the mountains by mules and then fed into the grinding apparatus. This would have created a coarse powder, ready for the application of mercury in the "patio process". 

This completes Part 9 of my Silver Mines of Hostotipaquillo series. I hope you have enjoyed it. If so, please leave any thoughts or comments in the Comments section below or email me directly. If you leave a question, please include your email address so that I may respond in a timely fashion. In the last part of this series, Part 10, I will show you the area where the silver ore was further processed into ingots and discuss how it was done.

Hasta luego, Jim