"When Miss Mi'er said that, it does look a bit similar..."

After listening to Zhen Mi's words, Yu Ji frowned slightly and stared at the images on the stone tablet for a moment, then nodded and said, "But if these two vertical lines represent the trunk of a big tree, then these four pictures from top to bottom

What does the image distributed inside the trunk of the big tree mean?"

"..."

Everyone in the Hu army shook their heads.

Wu Liang was also clueless at this moment.

From bottom to top, they saw the sacred mountain and the tree in the first image, saw the alternation of day and night, and also saw the armor and stomach worn by the Jiuli warriors in the second image.

They had also seen the strange insect in the third image, but it had never appeared again since entering this secret realm.

As for the pair of huge eyes that appeared in the sky in the fourth image, they had never seen it. Only Dian Wei vaguely remembered it in his subconscious when he fell into a coma and was affected by some mysterious spiritual power.

The fate...

But when it comes to connecting all these things together and interpreting them according to the order in the stele images, Wu Liang has no idea.

Under such circumstances, Wu Liang knew that he could not waste too much time on this stone tablet, so he had to turn around and told Ji and Cao Ni: "Old sir, please copy the images on this stone tablet first.

You should also keep the content in the image in mind and don’t miss any details, as this thing may come in handy at some point.”

"knew."

The two nodded in agreement.

Wu Liangze had already bypassed the stone monument and came to the large pure copper tree stump again under Dian Wei's protection.

Through the hole that Dian Wei had cut on the tree trunk before, Wu Liang didn't find anything valuable, because the hole was still solid pure copper without any impurities. He couldn't even figure out what had flowed out of the hole before.

Where did that drop of red liquid that looked like blood come from?

In this case, he could only shift the direction of exploration to the center of the large pure copper tree stump.

Wu Liang had already discovered from the beginning that the core of this large pure copper tree stump was hollow like a paulownia tree, and because the diameter of the large pure copper tree stump was so amazing, the diameter of its hollow tree heart also reached more than one meter. At first glance,

It looks like a well opening directly into the ground.

However, this is currently just a sense standing on the side. If he wants to find out how deep this hollow tree heart is and whether there is anything unknown hidden in it, Wu Liang must climb to the top of the large pure copper tree stump and then conduct it from a high position.

Further inspection.

"Brother Dianwei, come and help me."

With this in mind, Wu Liang climbed onto the large pure copper tree stump with Dian Wei's help, and then slowly approached the hollow in the center of the tree stump.

Dian Wei also jumped up and followed closely, holding his halberd.

But the subsequent investigation did not bring any surprises to Wu Liang.

What appears in front of you is just a vertical hole with a diameter of more than one meter. The inner wall of the vertical hole is also made of pure copper and looks very smooth. Even if a person with good skills uses the "chimney climbing method", it will be difficult to climb straight up and down.

Actions.

As for the depth of this vertical hole, it is still unknown.

Wu Liang looked down and could only see a black hole, not the bottom at all.

"Brother Zhuge, pass me a stone."

Wu Liang turned around and asked Zhuge Liang for a stone, and then told Bai Jingjing, "Jingjing, listen to the sound returned by clicking this stone and try to deduce the depth of the hole."

As he spoke, he already took the stone handed over by Zhuge Liang to the top of the vertical hole, then shouted "start" before letting go of his hand and letting it fall freely without any assistance.

In fact, even without the help of Bai Jingjing, you only need to remember the time when the stone falls to the bottom to make a sound, and you can calculate the depth of the vertical hole through the free fall formula learned in high school. As for the time error of sound transmission, as long as the vertical

If the hole is not too deep, it can be ignored.

But now that Bai Jingjing is here, Wu Liang has another object to compare with, and the conclusion drawn in this way is naturally more accurate.

What's more, he actually only needs a rough data now. The error is within a few meters, which is completely acceptable. There is no need to be so precise.

"..."

When everyone saw this, they immediately held their breath, fearing that making any noise would affect Bai Jingjing's judgment.

However.

One second!

Two seconds!

Three seconds...

Ten seconds!

Wu Liang remembered this secretly, but ten seconds had passed and he still did not hear the sound of the stone falling to the ground.

"this……"

Wu Liang couldn't help but be a little confused.

Even though it was only ten seconds, if he remembered correctly, the stone should have fallen about 490 meters in a free fall state without external influence!

Four hundred and ninety meters!

That's already a pretty terrifying height. You need to know that the propagation speed of sound in the air is only 340 meters/second. At this point, if you hear the sound transmitted back from the stone again, you can no longer ignore the time of sound transmission.

Wrong.

The important thing is that Wu Liang still hasn't heard any sound until now.

"Wu Youcai, not long after you let go, I seemed to have heard an extremely slight noise, but I wasn't sure if it was the sound of stones falling to the ground, so I didn't mention it to you in time."

Bai Jingjing also listened attentively for a long time, and finally said with a frown.

"Oh? Exactly how long after I let go? You can probably deduce the approximate depth from this?"

Wu Liang turned around and asked.

"About one breath later."

Bai Jingjing replied.

In this era, there is no concept of "seconds". Breaths are used as units for shorter periods of time. However, the unit of "breaths" is not accurate because normal people breathe about 12-20 times per minute. On average, one breath takes

That's 3-5 seconds.

Using this unit to calculate free fall motion will produce a large error.

But Bai Jingjing soon added: "If I heard correctly, the sound should be more than ten feet away from the ground where we are."

"More than ten feet?"

Wu Liangliang thought secretly.

A dozen feet is estimated as fifty meters. If calculated into the free fall formula, it means that the stone had just fallen for a little more than 3 seconds, which is indeed within the range of a breath of time unit.

This shows that Bai Jingjing must have heard correctly.

This vertical hole may have been so deep, and the stones had already fallen to the ground at that time...

But what exactly is at the bottom of this tree hole?

If there is some kind of hard material below, or a liquid like water, the falling stone will definitely make a loud noise, and it is impossible for only Bai Jingjing to hear it.

Wu Liang was puzzled and had to say to Zhuge Liang again: "Brother Zhuge, hand me another stone. Jingjing, listen carefully this time and try to hear what kind of thing the stone fell on."

How could the sound of landing be so slight?"

…

The second stone quickly fell into the hole.

This time it only took 2 seconds, Bai Jingjing immediately opened her eyes and said: "This time the sound became clearer, it sounded like it fell into a ball of soft and sticky stuff, and she was immediately absorbed by it.

It is swallowed up by something, so the sound is extremely small, and there is also..."

"Isn't this voice only four to five feet higher than us?"

Before Bai Jingjing could finish speaking, Wu Liang had already taken over and asked in a hurried tone.

"Did you hear it this time too?"

Bai Jingjing asked subconsciously.

"?"

Everyone else looked suspicious, even Dian Wei, who was standing on the large pure copper tree stump with Wu Liang.

They were trying hard to listen to all the sounds just now, but except for Bai Jingjing, they still didn't hear a single sound, especially Dian Wei, who could stand directly next to Wu Liang, and Wu Liang was not as good as Bai Jingjing.

With extraordinary hearing, why could Wu Liang hear this sound, but he didn't hear anything?

However, at this moment, Wu Liang had no intention of explaining to them. He immediately grabbed Dian Wei, jumped off the tree stump and urged everyone: "Quick! Brother Dian Wei, follow me, and the brothers also quickly backed away.

Let’s retreat ten feet away from this tree stump first!”

"Why is this?"

Everyone in the Hu army was even more puzzled.
To be continued...