APSIL -Chapter 92 Cao Chong Weighs an Elephant and the Principle of Archimedes

The moment the Emperor posed his question, everyone promptly forgot about the pitiful state of Imperial Academy Director Zhou Xun. The atmosphere instantly became animated.

After all, these young men, born into noble and official families, usually went out of their way to avoid the Academy’s instructors whenever they were off enjoying themselves. Even then, they were constantly criticized for being ignorant wastrels. Expecting them to sympathize with Zhou Xun was simply impossible.

Lu Sanlang, who had spent years being looked down upon, was naturally the first to shout, “Your Majesty, I dare not say for certain that the Founding Emperor’s plaque contains hidden manuscripts, but I do know that the Founding Emperor’s wisdom was unfathomable. He always planned far ahead. He was a sage unparalleled since the dawn of history. There is nothing he wouldn’t have done!”

As soon as Lu Sanlang spoke, Zhang Chen eagerly chimed in.

“Exactly! How could ordinary mortals like us possibly fathom the Founding Emperor’s intentions?”

Once the two leading playboys voiced their opinions, everyone else rushed to follow. One after another, they extolled the Founding Emperor’s greatness while subtly taking shots at the Imperial Academy.

For youths who had harbored resentment for years, it was practically instinctive.

Even Zhu Er, after being nudged repeatedly by Zhu Ying, awkwardly muttered that perhaps… maybe… quite possibly… the Founding Emperor really had hidden secret manuscripts inside the plaque.

Watching these aristocratic students pile on while kicking a man when he was down, Luo Siye wanted to say something in Zhou Xun’s defense.

But he couldn’t think of a convincing argument.

All he could do was stand off to the side, worrying helplessly.

As for Zhou Xun himself…

His entire body shook like a leaf in the wind.

His face had gone deathly pale, and his trembling lips couldn’t produce a single word.

Amid the noisy clamor, the Emperor smiled faintly before turning toward the silent Zhang Shou.

“Zhang Shou,” he asked with interest, “why aren’t you saying anything?”

Zhang Shou answered calmly, “Your Majesty, I was wondering what material the Founding Emperor’s plaque was made from.”

“Oh?”

The Emperor raised an eyebrow.

“So that’s what you’re thinking about?”

“If I remember correctly, it’s made from petrified ebony.”

“It was originally shipped to the capital by a local official who regarded it as a priceless treasure. The Veritable Records of the Founding Emperor mention that over a dozen massive logs were delivered. After the charred portions were removed, what remained was incredibly dense—hard as bronze or iron, and heavy enough to sink immediately in water.”

“When the Imperial Academy was completed, the plaques for both the Hall of Mathematics and the Hall of Natural Studies were carved from this wood.”

“The Founding Emperor insisted they be thick and substantial. Each plaque was so large that several men were needed just to carry one. There wasn’t enough timber left to make more afterward, leaving only scraps.”

“The imperial treasury still keeps quite a few of those offcuts today. I only have craftsmen carve small ornaments from them.”

“Although petrified ebony is occasionally discovered elsewhere, wood of such quality is rare.”

“And transporting it all the way to the capital was costly and burdensome. The Founding Emperor accepted the tribute but reprimanded the local officials for wasting resources. Since then, no one has dared send such timber over long distances.”

“At the time, some people complained that petrified ebony possessed excessive yin energy.”

“But the Founding Emperor simply replied that the Imperial Academy was full of yang energy, making it the perfect balance.”

“That shut everyone up.”

Seeing Zhang Shou still deep in thought, the Emperor beckoned.

“If you’re curious, come strike it yourself. The sound is quite distinctive.”

Since the Emperor had invited him, Zhang Shou naturally accepted.

Walking over, he crouched beside the plaque and tapped both its center and edges with two fingers.

After listening carefully, he discovered that it was difficult to determine whether it was hollow simply by sound.

He pondered for a moment before standing again.

Before he could speak, however, the Emperor smiled.

“So then, tell me.”

“Can you determine whether this plaque contains the Founding Emperor’s secret manuscripts… without destroying it?”

Zhu Ying’s heart skipped a beat.

She was just about to speak up and spare Zhang Shou from such a troublesome challenge when he happened to glance back at her and smile reassuringly.

Though he said nothing, a thought suddenly arose in her mind.

Could he actually have a solution?

“Your Majesty,” Zhang Shou said, “may I first ask the servant who accused Director Zhou a few questions?”

The Emperor casually waved his hand.

“Go ahead.”

After thanking him, Zhang Shou walked toward the servant still kneeling on the ground.

Yet when he was still three or four paces away, he deliberately stopped.

Only when he noticed A-Liu silently moving to his side from the corner of his eye did he finally relax.

Once bitten by an arrow… everyone looks like an assassin.

One couldn’t blame him for being cautious.

Squatting down, he met the servant’s gaze.

Seeing the man wearing the expression of someone who had already thrown caution to the wind, Zhang Shou asked gently,

“You claimed the Director has been trying every possible way to retrieve the secret manuscripts hidden inside the Founding Emperor’s plaque. How do you know that?”

“I saw it with my own eyes!”

“Every day, the Director visited the Academy treasury.”

“He would stand around the plaque, staring at it in fascination.”

“He often knocked on it with his fingers while muttering to himself.”

“I personally heard him mention the words secret manuscripts.”

“I see.”

“And how do you know there are exactly one hundred manuscripts?”

“The Director spent the last three years collecting unofficial stories about the Founding Emperor.”

“They’re all stored in the Academy library.”

“When I was cleaning there, I found one page he’d marked.”

“It specifically mentioned one hundred secret manuscripts of the Founding Emperor.”

“And…”

“I secretly sneaked into the treasury and knocked on the plaque myself.”

“If the middle weren’t completely hollow—as though a large section inside were missing—it wouldn’t sound like that.”

Turning toward Zhou Xun, the servant declared loudly, “If you don’t believe me, ask anyone in the Academy!”

“Doesn’t the Director visit the treasury almost every single day?”

“The only thing stored there worth looking at is this plaque!”

“So what else could he possibly be doing?”

Those words immediately enlightened Zhang Chen, Lu Sanlang, and the others.

Even Luo Siye began to hesitate.

He had worked alongside Zhou Xun for over three years.

Claiming Zhou Xun had personally removed the plaque was absurd.

But…

It was true that Zhou Xun often wandered around the treasury where the plaque was stored.

Luo Siye himself had witnessed it several times.

Once, out of curiosity, he’d asked why.

Zhou Xun had simply replied that he wished to admire the Founding Emperor’s calligraphy.

Luo Siye hadn’t thought much of it afterward.

Could it be…

Had Zhou Xun truly read too many unofficial tales and actually believed the ridiculous story about secret manuscripts inside the plaque?

But even if he did—

Retrieving them would mean destroying one of the Founding Emperor’s priceless treasures.

What exactly was he hoping to accomplish?

This wasn’t one of those fantastical novels where ancient plaques concealed treasure maps or secret vaults.

The Emperor smiled ambiguously.

“So there’s more to the story than I realized.”

“Director Zhou.”

“What do you have to say?”

“Absolutely false!”

“It’s absolutely false!”

Overwhelmed by humiliation and panic, Zhou Xun no longer seemed capable of defending himself.

He simply kowtowed again and again, tears streaming down his face as he repeated those same four feeble words.

Seeing that nothing useful would come from questioning Zhou Xun further, and noticing Zhang Shou walking back toward him, the Emperor smiled.

“So?”

“You’ve asked your questions.”

“Now what’s your solution?”

“I do have one, Your Majesty.”

Zhang Shou spoke confidently.

“If, as Your Majesty says, no more petrified ebony from that original batch remains, then I would indeed be at a loss.”

“But since the imperial treasury still possesses many of the leftover pieces…”

“I have an idea.”

“May I ask whether all of those scraps combined weigh approximately the same as this plaque?”

“Hmm…”

The Emperor hesitated before turning toward Chu Kuan.

Chu Kuan immediately replied with a smile.

“There are quite a lot of scraps.”

“They’ve never been weighed together, but judging by eye, the total weight should be roughly comparable.”

“However…”

“Although the state granaries possess large scales for weighing grain…”

“Accurately weighing something as massive as this plaque—and then matching that exact weight with loose scraps—would be quite difficult.”

Zhang Shou nodded.

“That doesn’t matter.”

“In the Records of the Three Kingdoms, there is the story of Cao Chong weighing an elephant.”

“With Your Majesty’s extensive learning, I’m sure you’re familiar with it.”

The Emperor smiled even more broadly.

“Naturally.”

Zhang Shou continued calmly.

“Since this plaque requires several men just to lift it, weighing it directly is impractical.”

“So we may treat it the same way Cao Chong treated the elephant.”

“Place the plaque into a specially made boat roughly the same size as the plaque.”

“Float it upon calm water.”

“Mark the waterline.”

“Then remove the plaque.”

“Next, place the ebony scraps into the boat until it sinks to exactly the same waterline.”

“Since the scraps are much smaller, determining the equivalent weight becomes relatively easy.”

The Emperor nodded slightly.

“Very good.”

“And then?”

Noticing everyone around him whispering about the story of Cao Chong, Zhang Shou continued.

“Next…”

“Tie ropes securely around the Founding Emperor’s plaque.”

“Lower it into a pool filled completely to the brim.”

“When submerged, it will inevitably displace a corresponding amount of water.”

“After the surface becomes completely still, remove the plaque.”

“Then record the new water level inside the pool.”

“Afterward…”

“Refill the pool completely.”

“Wrap the ebony scraps of equal weight in fishing nets and submerge them.”

“Finally…”

“Remove the scraps one by one.”

“If the water level afterward is identical to that produced by the plaque…”

“Then the two must occupy the same volume.”

“In that case…”

“The Founding Emperor’s plaque must be solid.”

Before he could finish, Lu Sanlang suddenly cried out in realization.

“I get it!”

“If the second water level differs noticeably from the first…”

“Then objects of the same weight must have different volumes!”

“That would naturally mean the plaque is hollow…”

“And that something is hidden inside!”

Zhang Shou had always held Lu Sanlang’s mathematical aptitude in high regard.

Seeing him grasp the idea so quickly, he smiled and nodded.

“Exactly.”

“In this way, we can determine whether the plaque is hollow—and whether it truly contains any so-called secret manuscripts—without damaging it.”

Of course, Zhang Shou knew perfectly well that this method was far from precise.

For a plaque this large, even under ideal theoretical conditions, splashing water, imperfect measurements, shifting centers of gravity, and variations in the density of different pieces of petrified ebony would all introduce significant errors.

Combining Cao Chong’s method of weighing an elephant with Archimedes’ principle would, in reality, produce only a rough estimate.

However…

The Emperor’s attitude had been rather suspicious all along.

Zhang Shou increasingly suspected that His Majesty merely wanted a plausible method, while caring very little about what the final measurement actually revealed.

Meanwhile, squeezed to the back by Zhang Chen and the others, Zhu Er’s jaw had nearly dropped to the ground.

It was already astonishing enough that Zhang Shou had devised such a solution.

But how had Lu Sanlang understood it so quickly?

Wasn’t he supposed to be the same kind of useless playboy as me?