The next morning, Lin Yi, for a rare change, didn't linger in bed. She pulled Gu Fang to wash up, hurried through breakfast, and set off.
Along the way, Lin Yi surprisingly didn't complain about the bumps or the slow carriage. Instead, she fidgeted restlessly, rubbing her hands together, looking as if she wished she could teleport to the eastern suburban estate.
Perhaps the driver drove steadily, or the horses were especially spirited, but Lin Yi felt the ride was faster and smoother than usual. Just as she was about to compliment it, Gu Fang smiled and called her out: "The estate is closer to the city; the journey is simply shorter."
Lin Yi: "..."
The carriage entered the estate and stopped near the cement testing ground. As they got off, they saw Xiao Zhu waiting nearby. Dark circles were faintly visible under her eyes, but her eyes shone brightly.
Lin Yi asked with concern, "Xiao Zhu, did you not rest well last night? If you need to, go take a nap; we can look around on our own."
"It's nothing, Madam!" Xiao Zhu grinned, showing eight teeth, her voice brimming with excitement she could barely contain. "This cement is truly miraculous! I was so thrilled I couldn't sleep a wink!"
Lin Yi was slightly surprised. Xiao Zhu was usually calm and composed, seldom so emotionally expressive. She hadn't even asked her to make reinforced concrete—how successful was the cement to make her forget her usual demeanor?
Xiao Zhu fluttered around her like a happy little sparrow, speaking rapidly: "Madam, you have no idea how incredible this cement is! Yesterday, we mixed it according to your recipe and spread it out. This morning, it had hardened like stone! We took iron swords and hacked at it, but left not a single mark on the ground!"
Gu Fang's gaze sharpened. "Truly not a single scratch?"
"Absolutely!" Xiao Zhu nodded emphatically, then paused, a bit deflated. "We thought it would be great for building city walls, so we tried to stand it up and plaster it, but it collapsed as soon as we tried."
Lin Yi thought to herself, of course—cement is essentially a paste; modern wall construction relies on a steel frame. Still, Xiao Zhu and her team were impressive for thinking of that and actually trying.
Just as she was about to praise them, Xiao Zhu's eyes lit up again. "So we came up with another idea: we fixed wooden boards on all four sides and plastered the cement inside. It's still not dry, but it seems to be standing!"
"Great idea!" Lin Yi praised. "Once the cement dries, it will indeed be quite solid, but this level isn't enough for wall construction. For building walls, I have a suggestion: mix sand and gravel into the cement to form bricks. Let them dry, then stack them like bricks and use cement as mortar. A wall built this way will be much more stable."
"Bricks?" Xiao Zhu tilted her head, puzzled. "Is that another way to use cement?"
"It's an advanced application of cement," Lin Yi explained with a smile. "Cement itself acts more like an adhesive. If used alone for walls, it's brittle. But when you add sand, gravel, and water, it binds various materials together, becoming as hard as rock yet tougher than pure cement. The resulting cement bricks are excellent for building walls and paving roads."
Xiao Zhu nodded, still half-understanding. "Then why don't we add sand and gravel to the cement used for flooring?"
Lin Yi was taken aback. "Didn't you lay a layer of gravel underneath first?"
"Huh? Does that count?" Xiao Zhu was even more confused.
Seeing she still didn't quite get it, Lin Yi slowed down and explained patiently, "When paving, the ground itself supports the cement, so no extra support is needed; simply plaster it on. The gravel underneath is to prevent the soil from softening and sinking." Noticing Xiao Zhu's eyes gradually clearing, she continued, "But when building a vertical wall, there's no support, so it easily collapses. That's why we need to make the cement itself stronger by mixing in sand and gravel."
She picked up a handkerchief to gesture. "Think of it this way: when cement is wet, it's sticky, right?"
"Yes!" Xiao Zhu replied.
"And can that stickiness hold sand and gravel?" Lin Yi asked.
"Yes!" Xiao Zhu clapped her hands, enlightenment dawning. "Sand and gravel are already hard. Once bound by cement, the whole piece becomes even harder!"
"Exactly," Lin Yi said, nodding. "But we need to experiment with the moisture content and coarseness of the sand, the size of the gravel, and the ratio with cement to find the optimal mix. Once the cement bricks dry, stack them and use a paste made from cement and fine sand to bind the joints. After stacking, apply a layer of cement over the entire surface for greater strength."
She paused, then added, "For building city walls, I suggest a trapezoidal shape—wider at the base and narrower at the top. That way, the foundation is stable and less likely to collapse."
"Trapezoidal?" Xiao Zhu blinked.
"It means wider at the bottom and narrower at the top, like a ladder," Lin Yi gestured with her hands, indicating a slope.
Xiao Zhu's eyes lit up. "So the base is heavy, and the wall won't tip over easily, right?"
"Yes. Alternatively, you can dig deep foundations. Just like laying gravel before paving, first compact a hard base underground, then build up from there," Lin Yi added.
"I understand! I'll remember it all and explain it to the craftsmen properly," Xiao Zhu said, nodding repeatedly.
Gu Fang and Lin Yi then inspected the flat, solid cement ground, testing its hardness with their own hands before leaving reassured. Xiao Zhu stayed at the estate to continue experimenting with cement brick production.
On the carriage ride back to the mansion, Gu Fang couldn't stop marveling at the cement's strength, remarking that if used for city walls, defending the city would be much easier. Lin Yi gave a proud hum and leaned over to claim several kisses as a reward.
After their display of affection, Lin Yi's eyes still held a hint of moisture, but she recalled something and tilted her head. "But both you and Xiao Zhu first thought of using it for walls. My original purpose for making this cement was to pave roads."
Gu Fang hesitated briefly before admitting, "A road that's too hard might injure horses' hooves."
"Ah, I see," Lin Yi said, catching on. "Then just put horseshoes on the horses."
"Horseshoes?" Gu Fang was taken aback. "What are those?"
"Shoes for horses," Lin Yi explained, tracing a U-shape with her fingers. "You make them in this shape and nail them onto the horse's hooves."
"Nails?" Gu Fang frowned. "Hammering nails into a horse's hoof... wouldn't that hurt?"
"No, it won't," Lin Yi said with a smile. "The outer part of a horse's hoof is like our fingernails; it doesn't hurt when trimmed. Just be careful about the nail length and don't drive them into the flesh, or the horse will kick out in pain."
Gu Fang listened, his expression gradually relaxing. After a moment's thought, he nodded. "Tomorrow, when I meet with Prince Ning, if the cement's merits gain his approval, I'll also present the horseshoe."
"Sounds good," Lin Yi replied lightly, leaning back against his shoulder.
The sounds of the city filtered in from outside the carriage, but the interior was quiet. Gu Fang looked down at the soft strands of Lin Yi's hair and suddenly let out a very soft chuckle.
"What are you laughing at?" Lin Yi looked up.
"I'm just thinking..." Gu Fang's fingertips brushed the loose hair by Lin Yi's ear, his voice gentle. "With Xiaoyi here, it feels like many difficult things suddenly have a way forward."
After returning to the General's Mansion and having lunch, Gu Fang excused himself with some pretext, but not before earnestly warning, "Xiaoyi, take your time discussing things with A Zhi. I won't disturb you from your business." He looked as if he truly feared interrupting, making Lin Yi both amused and exasperated.
Lin Yi first summoned A Fu and A Zhi. When asked about the progress of the kang, A Fu replied that they had found the most practical design. Since it was summer, it was a good time to promote it. If they could get the people to use it before winter, many fewer would suffer from the cold. Satisfied, Lin Yi let A Fu go about his work.
Only Lin Yi and A Zhi remained in the room. Lin Yi turned to A Zhi and asked gently, "I hear from the general that you've been farming for many years and are quite experienced?"
Though puzzled why the madam asked this, A Zhi replied respectfully, "Yes, Madam. I have farmed for many years."
"What do you mainly grow?" Lin Yi continued.
"Rice," A Zhi answered succinctly.
Good, exactly what she needed. Lin Yi's eyes flickered. "In all those years of growing rice, have you ever seen any rice plants that grew strangely or looked different from the others?"
A Zhi thought for a moment. "Yes. Occasionally, I've seen a few that were naturally short, or had leaves with unusual colors or veins."
Lin Yi considered that those might be diseased. She probed deeper: "Have you ever seen a rice panicle where the spikelet at the middle is especially shriveled, never opens, and doesn't shed pollen?"
This time, A Zhi was silent for a long time. He frowned, his gaze lowered. Finally, he looked up and shook his head. "I've never seen such a thing."
Lin Yi showed no disappointment. She understood that male sterile plants were a matter of chance. Even in her time, the predecessors had searched plant by plant, field by field with magnifying glasses, finding only six out of a quarter million—a ratio of about 1 in 250,000.
Research takes one-third luck and seven-tenths perseverance.
Lin Yi gave A Zhi detailed instructions: "From now on, if you find a rice plant in the fields like the one I described—with a shriveled spikelet that doesn't open—remember to immediately surround it with wooden boards to isolate it from other rice plants. See if it can produce grains on its own. If not, it might be the wild abortive we're looking for."
A Zhi was stunned, then cupped his hands. "Please enlighten me, Madam."
"A wild abortive is actually a male sterile rice plant," Lin Yi said, slowing down to be as clear as possible. "Rice is a self-pollinating crop. You can think of each rice plant as being hermaphroditic—able to produce grains without external help. A male sterile plant is one where the stamens have failed, producing no pollen, but the pistils are still healthy. Because it has no pollen, it can't produce grains itself. However, if pollen from other rice plants blows onto it, it might produce a few grains, but it's very rare. Do you understand what I'm saying?"
A Zhi lowered his head in thought for a long time before looking up. "I understand, Madam. But what is the use of this male sterile plant?"
"Its beauty lies in its ability to accept pollen from other rice plants as the father," Lin Yi said, her eyes shining. "Earlier, I mentioned that ordinary rice self-pollinates, so generations remain similar with little variation. But the male sterile plant is different—its pistils are healthy, so it can receive pollen from other rice plants and produce entirely new varieties."
Author's note:
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Here's a word of advice to any unfortunate transmigrators: don't try to find a male sterile plant on your own. In ancient times, without a magnifying glass, you'd likely go blind before finding one. Of course, if you have glass made into a magnifying lens, that's a different story.