Taiping Dao at the end of the Han Dynasty

Chapter 20: How to build the first pond in the civil engineering work?
A heavy rain in July alleviated the drought in Jizhou. The summer-sown beans, soaked in the long-awaited rain, came to life joyfully. The cracked earth healed itself, and many green grasses sprouted on the plains of Julu, even weeds sprouted in the bean fields.

However, from the summer sowing after the Lesser Heat to the harvest in late autumn and early winter, there are still four long months. No one knows whether another drought will strike when the beans are almost ripe, or whether the winter wheat can be planted this winter at all.

"Wheat can't be planted now, so we can only plant beans and millet. Next year will be another drought, and the year after that will also be a drought. Rainfall is scarce and unpredictable. Heaven above! This is the opportune time that my master, the great and wise teacher, divined by observing the stars at night!"

"Great One God! Three years of drought? Three years? Drought?!... "

The head of Julu Manor, Old Man Zhang, was shocked and his legs went weak. His beard trembled as he looked at Zhang Chengfu, Zhang Jiao's youngest disciple, in disbelief.

What did the three-year drought mean? No farmer didn't know, and no farmer wanted to believe it. But as a member of the Taiping Dao sect, as a devout believer who wore the yellow turban, Zhang Agong wouldn't doubt the Great Teacher's prophecy. He could only tremble as he muttered to himself.

"What should we do? What are we going to do? Can the immortal master pray for rain...?"

"May the world be at peace! We need to build a reservoir in the village. With a reservoir, we can collect as much rainwater and river water as possible to irrigate the millet when it's most water-scarce... at least we won't lose the entire harvest! We need to mobilize the whole village to build this life-saving reservoir together. Ideally, we could have an elder familiar with the terrain to help choose the location for the reservoir..."

"Yes! This is a major event for the village. Every household will contribute, men, women, and children will all come to work. Besides, everyone believes in the Yellow Heaven, so contributing people is easy... Repairing dikes, repairing ponds, repairing rivers..."

Grandpa Zhang held two plucked whiskers in his hand, pondered for a long time with a bitter face, and suddenly slapped his thigh.

"Oh, right! There's an old man named Li in the village who knows how to repair the river. He's from Wei County, and Master Ma brought him here personally several years ago! He's an old river worker, and I think he's also repaired the ponds, those twelve old ponds of Wei County! You wait here, I'll bring him over right now!..."

"The old river worker? Brought by Senior Brother Yuanyi himself?"

Upon hearing this, Zhang Chengfu's heart stirred. In this era, experienced and elderly river workers were undoubtedly highly skilled professionals. Like blacksmiths, they were extremely rare and usually under the control of the government.

The Way of Great Peace (Taiping Dao) spread widely in Jizhou, reaching hundreds of thousands, even millions, of people. While few members of the "cultured" gentry joined, many artisans in various counties and villages, having received its benefits, became believers in the Yellow Heaven. It seems my master and senior brother consciously gathered experienced artisans from the populace? Are there other skilled artisans in this core estate of our sect? This estate where my master sent him to farm seems far from ordinary!

"Young Master Zhang, if we're going to build a pond, we have to build it along the river, right next to this tributary of the Ming River. How big and deep should it be? Do you have a plan?"

"At least one hundred acres, two zhang deep. It would be best to take advantage of the terrain to reduce the amount of earthwork required."

Old Man Li was thin and small, but he walked with remarkable agility. His brows were furrowed on his tanned face, and after a while, he nodded.

“I understand. Then it can only be built on that big riverbank. But below that area are the good fields that the village has already cultivated. Once the pond is built and the water is stored, dozens of acres of fertile land will be flooded… What about Master Ma?”

"My senior brother said that I should make the decision. With three years of drought, water storage is the top priority, and we can't worry about the riverside land anymore."

"I understand. The hardest part of repairing the dike is acquiring the land. If you can make that decision, things will be much easier! Come with me, I'll show you!"

After finishing his words, Old Man Li quickly walked downstream along a tributary of the Ming River outside the village, heading towards the lower-lying area. Zhang Chengfu followed behind, pondering Old Man Li's words and gradually understanding their meaning.

"The hardest part of building a pond is acquiring land?... Yes! Almost all the land along the river is good land. And such good land is bound to be owned, and it is often the best irrigated land of powerful families. Right now, in order to irrigate a thousand acres, we have to build a hundred acres of ponds. If it were a larger water conservancy project to irrigate a thousand hectares, then we would have to acquire a hundred hectares of land!"

"Of these 100 hectares of land, how much is fertile riverside farmland? How much belongs to powerful and wealthy families? Can it just be flooded like this? The completed water conservancy project is meant to irrigate the entire county and benefit the common people. But the flooded farmland belongs to powerful and wealthy families. What kind of logic is this? Anyway, they occupy the riverside and won't lack water. They don't care about the dry fields outside... That's why land acquisition is the most difficult!"

It's worth mentioning that the "Field Method" in the Han Dynasty's *Nine Chapters on the Mathematical Art* records that one hundred mu equals one qing. Before his death, Prime Minister Zhuge Liang wrote in his will to the Later Ruler, "Fifteen qing of meager land," which is 1,500 mu. A prime minister's family in Shu only owned 1,500 mu of land. This was indeed extremely frugal among the powerful families of the late Han Dynasty.

"Look, this is it!"

After walking for a while, the group arrived at the large riverbank that Old Man Li had mentioned. A tributary of the Ming River flowed through this area, causing the terrain to drop significantly, forming a natural depression. The depression was estimated to be several dozen acres in size, and many fields had been cultivated there. However, due to the drought, no new crops were planted after the wheat harvest; the land was left to recover its fertility.

The nearby tributary of the Ming River had once dried up due to drought, possibly because it had been drained by a powerful family upstream. Now, with the rains, some water has come from upstream, trickling down and barely forming a small river.

"Is this the best location to repair the dike?"

"Yes! That's it! There's a riverbank on the western half. We just need to enclose the eastern half and build a half-dam! The land in this riverbank has been cultivated, and the surrounding stones and tree roots have all been cleared away, saving a lot of effort. Once the dam is built, we just need to dig the bottom of the pond deep enough. Then we'll lay a layer of soil, tamp it down firmly with large wooden piles, lay another layer, and tamp it down again. After tamping down three layers, that will be the bottom of the pond."

Old Man Li jumped down the riverbank and walked from west to east, talking incessantly as if he had a perfect picture of the pond in his head. Zhang Chengfu followed behind him, carefully noting down every word, which was all based on the master craftsman's decades of experience.

"Look! The western half is against the riverbank, and the dam is already there. All we need to do is clear the riverbank and lay some erosion-resistant gravel and sand. We can then directly excavate the gravel slope further west..."

"The eastern half of the dam had to be built by ourselves using clay. We'd lay a layer several inches thick, then moisten it with water, tamping it down repeatedly with a sledgehammer, and then lay another few inches, until it reached two zhang (approximately 6.6 meters). To make it last longer, long wooden stakes were driven into the water-facing slope every few zhang, and the exposed parts were connected with horizontal beams or bamboo fences. Yes! Like a fence, it supported the water flow—that's the weir. We built some stones at the bottom of the slope to protect against erosion, and then laid some gravel on top, just like the western half..."

"What I'm saying are all requirements for the large pond. If it's only two zhang deep, the requirements for the dam aren't actually that high. As long as it's not too straight, built in a curved or horseshoe shape, it can withstand the force. Even if the wooden piles are driven in a bit sparsely, there are fewer stones, and the earthen dam isn't built very solidly... it can still last for at least ten years!..."

After finishing his explanation, Old Man Li had reached the East River Estuary, the location for the dam construction. He measured the width of the river mouth with each step, every single one precise, like a human-shaped ruler. In those days, water conservancy projects relied on "human-shaped rulers," measuring by the number of steps taken. As for a measuring rod that could stretch for over a hundred steps? Who possessed such a treasure? It wasn't like building an emperor's tomb…

"Ten steps...twenty steps...one hundred steps...two hundred steps..."

After listening to the old river worker's account, Zhang Chengfu gradually envisioned the pond. It was simpler than his initial plan, but more practical and with more refined details. This kind of seemingly simple yet ingenious design best showcased his skill. He followed behind Old Man Li and measured it with his own steps. Then, the two of them simultaneously reported their measurements in meters, according to their stride widths.

"The old man estimated that it was a little over a hundred zhang from north to south."

"One hundred and twelve feet!"

The old man and the young boy exchanged a glance and smiled knowingly. Zhang Chengfu asked the old man to continue, and Old Man Li pointed to the riverbank to the west, estimating the length. "We just passed by; it's about eighty zhang from east to west. Eighty zhang wide and a hundred zhang long, that's about a hundred mu! The amount of earth that needs to be excavated isn't much; just dig down half a zhang and compact the soil. If we're in a hurry, half a zhang is enough. The main work after that is building the dam! If we work quickly, with three hundred people from the village, it can be finished by early winter!..."

"Um…"

Zhang Chengfu took out a piece of yellow paper and began to calculate with his charcoal pencil. He had just walked over and measured the east-west distance to be 78 zhang and the north-south distance to be 112 zhang. One Han zhang is 2.31 meters, and one Han mu is 461 square meters. After multiplying and dividing for a long time, he found that it was indeed 101 mu!
The result Old Man Li rounded down to the nearest whole number was actually quite close to his careful hand calculation. This level of precision was sufficient for agricultural production and water conservancy projects. Perhaps, the arithmetic he taught the children could be further simplified with additional methods…

“挖上小半丈，算1米。百亩是4.6万平。那就是4.6万土方的挖土量？村里出300人，老弱妇孺2人折算1丁，大概200多丁。520个少年童子，折算260丁。我一个人的力气能算2丁…估计一人百方的挖土量，挖两个月也就每天1-2方多，确实不算大！”

"As for the dam, it will be 112 zhang long and 2 zhang high. The top will be half a zhang wide, and the bottom will be one and a half zhang wide, averaging one zhang. That's about 2,800 cubic meters of earth, which is acceptable! The excavated earth can be used to build the dam on-site..."

Zhang Chengfu calculated carefully for a moment, and finally had a complete understanding. Calculation techniques were used in situations like this, in real production and construction. Old Man Li, watching him "divinate" on the yellow paper, was so intimidated that he shut his mouth, not daring to disturb him. After a while, seeing that Zhang Chengfu had finished, he cautiously approached and asked...

"Master Zhang... have you figured it out?"

"Hmm, I've figured it out."

"So, is this divination auspicious or inauspicious? Can this pond be repaired? Should we offer a sheep's head as a sacrifice?"

“?…”

Zhang Chengfu opened his eyes wide, looked at the arithmetic on the yellow paper, and then at the cautious Old Man Li. After a few breaths, he realized what was happening and chuckled.

"Grandpa, it's auspicious! Very auspicious!..."

"Oh! That's good, that's good! So, should we build a pond?"

"We'll build it! We definitely will! The beans are all planted now, and there's not much work to do in the fields. We can start by marking out the base of the dam and digging earthwork. After the bean harvest in late autumn, the whole village will work together to build the dam!"

Zhang Chengfu looked at the planned pond with a smile in his eyes, already somewhat impatient. However, he suppressed the urge to act immediately and said with a smile.

"Oh, right, there's one more important thing before we start work!"

"What's the matter?"

"We need to call those teenagers over. Let them stand here on the riverbank and calculate the entire project we've outlined themselves!..."

As an "excellent" teacher, how could I let go of any opportunity to make my students frown, work hard, and conduct on-site calculations?

Without a word, Zhang Chengfu gathered over five hundred boys. He then told them what they needed to calculate: each of the 52 groups had to draw a pond and list its dimensions and the amount of earthwork to be done. The ten groups with the most accurate calculations would receive an extra lunch each day for ten consecutive days. The remaining groups would just watch, and the last ten groups would have to wash the wooden bowls of the top ten. Well, not very harmful, but quite humiliating.

After saying this, he smiled and watched all his disciples running around on the riverbank like a bunch of mud-covered monkeys. Old Man Li, standing beside him, stared wide-eyed, quite amazed.

"This...this is how the disciples of the Great Teacher of Virtue are taught?"

"They are not Master's disciples, but my disciples!"

Zhang Chengfu smiled, quite proudly. Old Man Li tilted his head, looking at the young man whose beard hadn't even grown yet, opened his mouth, and finally only said...

“When I was in Ye City, I saw some teachers from aristocratic families teaching their disciples… They all wore hats, deep robes, jade pendants, and square shoes. Their every word and action was quite elegant, and they spoke classical Chinese… But they were very different from what you, Master Fu, teach.”

"Yes! The sons of the gentry learn for the sake of the gentry, of course. But the sons I teach learn for the sake of the farmers. The former float in the sky, the latter walk on the ground. Some differences are only natural!"

Zhang Chengfu smiled and offered a brief explanation, refusing to elaborate. Then, his eyes gleamed as he looked at Old Man Li with interest and asked a question.

"Grandpa, you were in Yecheng, Weijun before? Since you have such good skills in repairing dikes and ponds, you must have been valued by the government, right? Why did you come to Julu County?"

Upon hearing this question, Old Man Li remained silent for a moment, then sighed.

"Alas! The old man has no choice... This is a long story!"

"It's alright, we can talk slowly. These busy young men definitely won't be able to figure it out in a short time. They might not even finish today..."

Zhang Cheng looked at Old Man Li with encouraging eyes and waited patiently. Old Man Li sighed again and spoke.

"The old man was originally a 'waterworker' for the Twelfth Canal of the Zhang River. His family had been repairing rivers for generations, and their names were recorded in the government's register as government craftsmen. Because of his skills, he was a 'master waterworker' in his early years, and his family owned several dozen acres of poor land..."

"The Hutuo River to the north, the Qinghe River to the east, the Zhang River to the south—which river haven't I repaired? Every time the government conscripted laborers, I was put in charge of a hundred or so. Until five years ago, during the great plague at the beginning of the Guanghe era, the laborers repairing the rivers died and fled. They couldn't gather enough able-bodied men to repair the Zhang River, and then the Zhang River overflowed its banks, flooding the fertile fields of the powerful families along the river. The county official in charge of the rivers immediately pinned the blame on me..."

"The old man knew then that there was no way to defend himself; he could only flee. If he didn't flee, he would surely be caught and beheaded! And the only ones he could turn to, the only ones willing to protect us craftsmen, were the immortal masters of the Way of Peace. What a blind world this is!..."

(End of this chapter)