Late into the night, the Northern Frontier Administrative Office was still lit.
The footsteps of the soldiers on night patrol had already faded into the distance after stepping across the accumulated snow. All that remained was the faint sound of the corridor lamps swaying in the wind.
Xia Lanshi was still sitting before the desk, with several scrolls of documents and military reports spread beside him. The candle flame flickered faintly in front of him.
He had already grown accustomed to reading under such light, accustomed to bringing the paper closer in order to see the edges of those ink marks clearly.
When Chi Banyue came in carrying a bowl of medicine, she did not deliberately lighten her footsteps, as if she had intentionally wanted him to know someone had come.
She placed the bowl of medicine on the desk. The medicine swayed gently in the bowl, releasing a bitter, herbal smell.
“Drink it first,” she said. Her tone was gentle, but left no room for negotiation. “It will be even more bitter when it gets cold.”
Xia Lanshi did not argue. He put down the documents and picked up the bowl of medicine.
He drank very slowly. Each mouthful paused between his lips for a moment before he swallowed, as though he were getting used to that bitter taste.
Chi Banyue stood beside him without urging him, simply waiting quietly for him to finish.
She noticed that Xia Lanshi had his head tilted slightly, as though avoiding the side where the candlelight was brightest.
“Are your eyes bothering you again?”
“It’s nothing,” Xia Lanshi said.
Chi Banyue did not argue. She merely looked at him.
She had already grown accustomed to the expression Xia Lanshi wore whenever he said, “It’s nothing”—calm, gentle, as though he were talking about something unrelated to himself.
Just like their master.
But she said nothing, because she saw Xiao Yuan lift the curtain and walk in.
When Xiao Yuan entered, he was holding a wooden box in his hands.
He glanced at Chi Banyue, then at the bowl of medicine in Xia Lanshi’s hands, as though confirming that something had already been completed.
Xia Lanshi put down the bowl of medicine and raised his head. “His Highness. It’s so late. Is there something urgent?”
Xiao Yuan did not answer immediately.
He merely placed the wooden box on the desk.
He opened the wooden box. Inside were rows upon rows of neatly arranged lenses, each one set into a groove lined with velvet.
Chi Banyue moved closer curiously and lowered her head to look at those neatly arranged lenses. Under the candlelight, they reflected a thin layer of light.
Xia Lanshi’s gaze fell upon those lenses and paused slightly. He did not ask anything, merely watched quietly.
Xiao Yuan took out several rows of lenses with metal frames, along with a carefully folded sheet of instructions.
“What is this?” Xia Lanshi finally asked.
“A trial lens set.” Xiao Yuan unfolded the instruction sheet and spread it out on the desk. “Doctor Su asked me to bring it back. He said this can be used to test your eyes.”
Xia Lanshi’s fingers moved slightly at the edge of the desk.
His gaze fell upon the line of writing on the instruction sheet:
Have him sit somewhere with stable lighting, place this in front of his eyes, and try them one at a time, changing one lens at a time.
The handwriting was neat, and every step was written clearly.
Xia Lanshi was silent for a moment, quickly finding the answer in his mind. “Did His Highness say it?”
“I saw it.” Xiao Yuan interrupted him, his tone as calm as if he were stating something that required no explanation. “When you read the accounts at night, you lean very close.”
Xia Lanshi did not respond.
That was indeed the truth.
Xiao Yuan pushed the instruction sheet in front of him. “Try it first.”
He picked up the first lens and held it out in front of Xia Lanshi, carefully recalling the movements Su Muchen had demonstrated.
“Cover your left eye. Look through this.”
Chi Banyue walked to the side and folded her arms, simply watching.
Xia Lanshi lowered his head to look at the testing steps written on the paper, then raised his eyes to glance at Xiao Yuan.
Then he moved his gaze back to the lens and reached out to take it.
“Then I’ll try it.”
Following the instructions, he picked up the first lens.
The lowest prescription.
He raised his hand to cover his left eye. When he placed it in front of his right eye, his gaze passed through the lens and landed somewhere on Xiao Yuan’s face.
He frowned slightly.
“There’s no difference.”
“Change to the next one,” Xiao Yuan said.
One lens, two lenses, three lenses.
He asked very slowly. Before every change of lens, he would let Xia Lanshi lower his hand and rest for a moment.
When they reached the fourth lens, Xia Lanshi’s fingers paused at the edge of the frame.
He did not speak immediately. He simply looked through that lens toward the scroll of documents on the desk again.
The characters seemed as if something had rearranged them. Their edges had become much clearer, no longer slightly blurred outward as before, as though separated by a thin layer of fog.
“This one is clear,” he said, his voice slightly louder than before.
Holding the lens, he looked toward Xiao Yuan, as though this were the first time he had seen this person’s outline and expression so clearly.
Previously, he had always needed to squint and confirm for a long time. Now he could see more details.
Xiao Yuan took a look and memorized the prescription of that lens.
Xia Lanshi switched to his left eye and began testing again.
He tried several lenses, then stopped at one of them.
Although he did not say anything, Chi Banyue saw his expression change.
Very slightly, as though he had merely blinked once, and then it returned to calmness.
He lowered his head and looked at the lens between his fingers.
“This one is clear,” he said.
His tone was certain.
Xiao Yuan nodded.
“That’s it?” Chi Banyue asked.
Xiao Yuan wrote down the two sets of numbers and put them away against his chest.
“This is only the preliminary test. Doctor Su said the actual item still needs to be specially made.”
Xiao Yuan put the last lens back into the wooden box.
On the record sheet, the prescriptions for the left and right eyes had already been clearly marked. At the corner was also a supplementary note:
“Significant photophobia.”
Xia Lanshi blinked slightly.
He did not ask what the result was, because he had already read the answer from Xiao Yuan’s expression.
“The prescription is confirmed,” Xiao Yuan said, folding the paper and putting it inside his robe. “The next time I go to Guichen Studio, I’ll bring the results to Doctor Su.”
Xia Lanshi nodded.
He knew that Xiao Yuan had always cared about him. It was just that, because of certain reasons, that concern had now become even more obvious.
Neither of them said it aloud.
Xiao Yuan closed the wooden box again and placed it at the corner of the desk. He did not hurry to leave.
Xia Lanshi then raised his head and looked toward Xiao Yuan.
His gaze was more focused than usual.
As though only now had he truly seen the weariness on Xiao Yuan’s face clearly. It was not wrapped in layer upon layer of hard defenses as he remembered it. It simply remained quietly at the corners of his eyes, like someone who had walked a very long road and had finally been willing to stop and rest.
“His Highness, have you been failing to rest on time again recently?” Xia Lanshi asked.
Xiao Yuan did not answer.
The answer was already obvious.
Xia Lanshi then turned toward Chi Banyue.
Chi Banyue was holding the bowl of medicine, which had already become somewhat cold. Only now did he notice that the dark shadows beneath her eyes were also deeper than usual.
Previously, when he looked at her, he could only see an outline, as though through fog.
Just now, through that lens, he had discovered how obvious those dark shadows actually were.
“Miss Banyue as well,” he said gently.
Chi Banyue froze for a moment. “Me?”
“The dark shadows beneath your eyes have become heavier.”
Chi Banyue wanted to say something, but in the end she only laughed. “Lord Xia, now that you can see clearly, the first thing you do is come and lecture me?”
Xia Lanshi did not answer. He merely smiled lightly.
That smile was the most relaxed one he had shown in these recent days.
Xia Lanshi noticed that Xiao Yuan’s movements had stopped, as though there was something else.
Xiao Yuan took out another wooden case and gently placed it on the desk.
The wooden case was slightly smaller than the box that had held the lenses just now, without any unnecessary decoration.
But Xia Lanshi noticed that Xiao Yuan’s movement when setting it down was gentler than usual, as though he were putting down something that should not be treated casually.
He opened the wooden case.
Inside was dark-colored velvet. Three pocket watches were each set into their own fixed recesses, their hands quietly moving. Each one had a different style.
Chi Banyue’s gaze fell upon the wooden case.
She noticed the differences in style between the three pocket watches. Each one seemed to have been carefully selected.
Xiao Yuan picked up the rose-gold pocket watch in the middle.
He handed it to Chi Banyue.
“This one is for you.”
When Chi Banyue reached out to take it, her fingertips paused lightly over the patterns of wheat ears and grapes, as though feeling the depth of the engraving.
She turned it over and, when she saw the mirror, raised her brows slightly.
“It’s even clearer than a bronze mirror.”
She looked at the mirror with some surprise, as though it were the first time she had seen her own face so clearly.
“You need it,” Xiao Yuan said.
Chi Banyue did not argue. She lowered her head and carefully put away the pocket watch.
“Thank you for His Highness’s gift.”
Those words were too light for the relationship between her and Xiao Yuan, so light that they were insufficient to carry the weight of this pocket watch.
But she still had to say them.
Xiao Yuan picked up another pocket watch, this one mist-silver in color, and handed it to Xia Lanshi.
Xia Lanshi reached out and touched the patterns on the watch cover.
Although a pocket watch was merely a tool to him, he had to admit that he truly liked it.
He opened the watch cover and saw a line of extremely fine engraved marks on it, as though they had been scratched by some sharp pen tip. The lines were so fine that they were almost invisible.
It was not writing from Dashing, at least not writing that he recognized.
But some kind of premonition told him that it was a line of words that had been deliberately engraved.
He raised his eyes and looked toward Xiao Yuan.
Xiao Yuan saw that his gaze had stopped on those engraved marks. After remaining silent for a moment, he still spoke.
“Foreign writing from Doctor Su’s world.”
He paused.
“It means, ‘As long as you are alive, that’s enough.’”
The tent fell silent for an instant.
Xia Lanshi did not respond. He merely lowered his head and looked at those words, his fingertip lightly sliding across the engraved marks, feeling the depth of the traces.
The engraving was still very new, as though it had only recently been carved.
And those words did not sound like something Doctor Su would say.
A figure appeared in his mind.
For some reason, he felt that these words carried something extremely heavy, like a certain distance that could not be put into words.
This was not merely a compromise with life. It was more like a declaration of squeezing one’s limits to the very last moment.
After a while, Xia Lanshi put the pocket watch into his sleeve.
Only then did he raise his head and look toward Xiao Yuan.
“His Highness did not give these three pocket watches merely as rewards.”
Xiao Yuan did not deny it.
“The Northern Frontier needs a common time. These pocket watches are only the beginning. I need to establish a new time system so that the army, merchant caravans, and document exchanges all use the same time.”
Chi Banyue sat to the side, her fingertip lightly tapping the edge of the pocket watch.
“The army uses pocket watches, while the Administrative Office uses a clepsydra? Or something else?”
“A clock tower,” Xiao Yuan said. “Linbei City needs a clock tower.”
He paused, then turned toward Xia Lanshi.
“The clock tower blueprint book Doctor Su provided earlier has already been organized. The drawings, structure, parts list, and assembly steps are all there. Doctor Su has already rewritten all the materials into a version that the craftsmen on our side can understand. The dimensions are marked using proportions, and the steps have also been reorganized. As for the materials, the blueprint book notes: the gears are to be cast from bronze, and the bearings are to be made of iron or steel. Iron with insufficient purity can be improved through heat treatment. But there is only one copy. It cannot be allowed to circulate outside. We need to build it in batches for trial.”
Xia Lanshi raised his eyes slightly.
“The clock tower project is enormous and could easily arouse suspicion from the imperial court.”
He had already read that blueprint book several times. If it could truly be built, it would change history.
“Build it separately,” Xiao Yuan said. “Different craftsmen will be responsible for each part. They must not communicate with one another, and we cannot let them know what they are building.”
Xia Lanshi was silent for a moment, as though taking that sentence apart in his mind and then putting it back together.
Then he spoke, his tone calm.
“It needs to be divided first.”
His fingertips lightly tapped the surface of the desk several times, as though measuring a chessboard that did not exist.
“First batch: divide it into three workshops.”
Xia Lanshi’s voice had no fluctuation. His speech was steady, yet carried a certainty that sounded less like a “suggestion” and more like something he had already begun calculating.
“Woodworking workshop: only make gear models. Blacksmith workshop: only forge the gears. Coppersmith workshop: only make the bearings. Doctor Su’s blueprint book specifies that the gears are to be cast from bronze, while the bearings are to be made of iron or steel. The woodworkers first make the models to correct the number of teeth and dimensions. The blacksmiths make the bronze gears according to the models. The coppersmiths make the bearings.”
Chi Banyue raised a brow.
“Three workshops? Isn’t that a little too few?”
Xia Lanshi said, “The first stage does not require all the components to be ready at the same time. We only need to verify it. The woodworkers make the gear models to correct the dimensions and number of teeth. The blacksmiths make the bronze gears according to the wooden molds, and the coppersmiths make the bearings. After everything is finished, we assemble it for a trial. If it doesn’t turn, then the gear ratio was calculated incorrectly. Change it.”
Xiao Yuan asked, “What about mathematics? There is a gear ratio in the blueprint book.”
Xia Lanshi said, “Don’t let the craftsmen calculate it. If you let the craftsmen calculate it, they will make mistakes. I’ll calculate it. After I finish calculating the relationship between the gear ratio and the escapement timing, I’ll hand it over to the craftsmen to manufacture.”
Chi Banyue was slightly stunned, then leaned back a little.
“You even accounted for the fact that the craftsmen won’t be able to learn gear ratios.”
Xia Lanshi did not deny it.
“What is written in the blueprint book is structure, not production. If you let the craftsmen directly build the clock tower, they won’t be able to do it. They need tasks that have been divided apart. Each one is simple. Put together, they are difficult. And the step where they are put together does not belong to them.”
He flipped the documents on the desk to a blank page and picked up his brush. On the paper, he drew a line, with a circle at each end.
“Second stage,” he said.
The tip of the brush drew a second branching line across the paper.
“Stoneworker workshop: only build the tower. The tower will use locally sourced Northern Frontier stone. There is no need for fine carving, only stability. First determine the dimensions of the tower, leaving space inside for the gravity-weight passage and the time-reporting mechanism.”
Chi Banyue said, “The foundation and wall structure of a clock tower are different from those of residential houses. If the stoneworkers aren’t told that this is a clock tower, they’ll build it according to their usual habit of constructing fortresses.”
“So someone needs to tell them how to build it,” Xia Lanshi said. “Have the stoneworkers build the shell according to the drawings, but do not tell them about the internal structure. Once the walls are completed, install the gears and gravity weights.”
Xiao Yuan said, “So the workshops need to be divided into more layers.”
“Five layers.”
Xia Lanshi’s brush did not stop. On the paper, he drew an upside-down tree—the roots were the clock tower, and the branches and trunk were five workshops.
“Woodworking, blacksmithing, coppersmithing, stonework, mathematics. The five workshops each operate independently, without knowing the purpose of the finished product.
“When the woodworkers make the gear models, they think they are making some kind of mechanism.
“When the blacksmiths forge the bronze gears, they think they are making some kind of ritual vessel.
“When the coppersmiths make the bearings, they think they are making axles for carts.
“When the stoneworkers build the tower, they think they are building a beacon tower.
“Mathematics only provides the gear ratios and does not ask about the purpose.”
Chi Banyue asked, “Then who will assemble it in the end?”
Xia Lanshi put down his brush.
“I will.”
That single word fell into the tent, and no one contradicted it.
Xiao Yuan looked at the upside-down tree on the paper. After a moment of silence, he asked, “Do you have any ideas about the people for the workshops?”
“For the first batch of craftsmen, their ages should be between fifteen and twenty,” Xia Lanshi said. “Craftsmen who are too old already have their own habits and will question the drawings. Young craftsmen have not yet learned to ask why. They will follow instructions and learn. By the time they begin asking why, the clock tower will already be finished.”
Chi Banyue asked, “Are there enough craftsmen for the workshops?”
“Not enough,” Xia Lanshi said. “So we need Tingxue Pavilion.”
Chi Banyue’s movement stopped for an instant, as though she were already anticipating the second half of Xia Lanshi’s sentence.
Xia Lanshi raised his head. His pale-red eyes reflected a trace of light in the candlelight.
“Tingxue Pavilion will transport the talent.”
Chi Banyue did not answer immediately.
She lowered her head and touched the pocket watch she had placed against her chest, then raised her head.
“What are you going to transport?”
“There is an old clockmaker in the south,” Xia Lanshi said. “He retired more than ten years ago and no longer accepts work. But when he was young, he once built a mechanical water clock for a merchant guild in the Southern Frontier. He polished the gears himself. I want him to come to the Northern Frontier.”
Chi Banyue said, “He has been retired for more than ten years. He won’t come.”
“So someone needs to persuade him,” Xia Lanshi said. “There is no need to tell him that coming to the Northern Frontier is for building a clock tower. We only need to tell him that there is a batch of bronze gears that need polishing, and the pay is three times the market price. After he finishes polishing the first batch of gears, he will become curious about what those gears are for. As long as he becomes curious, he will stay.”
Chi Banyue was quiet for a moment, then laughed softly.
“You even accounted for the old clockmaker’s curiosity.”
Xia Lanshi did not deny it.
Chi Banyue asked, “What else?”
“The best bronze,” Xia Lanshi said. “I know of a mine with extremely high-quality material, but the mine owner only sells to merchant caravans he knows and does not deal with the government. We need to purchase it under Tingxue Pavilion’s name.”
Chi Banyue nodded, as though recording those words in her mind.
“And the best wood,” Xia Lanshi added. “The pine in the Northern Frontier is too soft and is unsuitable for making precision gear models. Southern rosewood or ironwood has sufficient hardness, does not deform easily, and has a smooth surface after polishing. But this kind of wood is also valuable in the south, and it is controlled by the imperial court. All government purchases of timber have to be reported. Tingxue Pavilion should have a channel.”
Chi Banyue’s fingertips paused for an instant on the edge of the pocket watch, as though weighing something.
“We do,” she said. “Tingxue Pavilion has two merchant caravans that travel by sea. We can use the name ‘imported exotic decorative wood’ to bring it through customs and avoid the court’s restrictions. But the quantity cannot be too large. Small batches can be transported each year.”
“That’s enough,” Xia Lanshi said. “The first batch of gear models doesn’t require much wood. First make a prototype. Once the prototype can turn, then we can discuss mass production.”
Xiao Yuan lightly tapped the surface of the desk, as though closing the net.
“There are iron mines in the Northern Frontier, but we have to dig them ourselves. The methods for processing and smelting the ore have already been written clearly in Doctor Su’s materials. The workshops will be established in batches, the talent transported in batches, the wood brought in batches, the bronze purchased in batches, and the iron mined ourselves. Every stone of the clock tower, every gear, when looked at separately, is nothing more than something ordinary. Put them together, and only then do you get that tower.”
Chi Banyue asked, “How long?”
Xia Lanshi said, “The blueprint book from Doctor Su specifies a six-month trial-and-error period. If everything goes smoothly, the first functioning clock tower can be completed in as little as half a year. If the craftsmen take longer to work together, it will take about a year.”
The tent was silent for a while. The sound of the wind seeped through the gap in the tent curtain, making the candle flame sway slightly.
Xia Lanshi lowered his head and looked at the tree-shaped diagram on the paper. His fingertip paused for an instant on the branch marked “Mathematics.”
“His Highness, how much error does the timekeeping of this pocket watch have compared with the timekeeping instruments from Doctor Su’s side?”
“Almost negligible,” Xiao Yuan said.
Xia Lanshi nodded and did not ask further.
He looked at the upside-down tree on the paper. After a moment, he spoke.
“If the five workshops operate simultaneously, it can be completed in half a year to a year. When it stands, the people of Linbei City will become accustomed to looking up to check the time. The people of the Northern Frontier will, without realizing it, live according to the same rhythm.”
Xiao Yuan withdrew his hand, as though confirming that all the pieces on the chessboard had already been placed.
“If one day I must lead the army south,” Xiao Yuan said, “then the Northern Frontier must already be a city that can stand on its own. A city with grain, medicine, and time.”
He stood up. When he reached the entrance of the tent, he stopped for a moment without turning back.
His tone was calm, yet not light.
“Huaiyu, Banyue, thank you.”
Those words were very short, without excessive embellishment, yet they remained in the tent for a moment before fading away.
Xia Lanshi did not respond.
He merely looked at the tree-shaped diagram on the desk, his fingertip lightly tracing the line marked “Woodworking,” as though confirming whether this tree could take root in the frozen soil of the Northern Frontier.
Chi Banyue lowered her head and unfastened the pocket watch, wiping its surface once with her sleeve before tying it back onto her sash. Her movements were very light, as though putting away something whose weight had already been confirmed.
The tent fell silent.
The candle burned steadily on the desk.
Neither of them said anything more.
Because the plan had already been completed.
What remained was for each of them to go and do what needed to be done.