After listening to Lao Niu's explanation, Xu Qianyun asked with some doubts:

"If you want to say that the cave may be connected, I believe it, but this water cave is so deep, so much water, such a strong water pressure, if there is really a cave connection, then the end is still water, and the snake still can't get out." ”

Expert Niu and Expert Xu, as well as all the others, all rolled their eyes in unison when they heard this.

Expert Xu explained: "No, it's like a rubber pipe, you fill half of the water into it, and then lift the two ends of the pipe and lift it to the same height." You will find that the water surface in the two pipes is also at the same height, which is the U-shaped pipe level phenomenon. If there are other caves under the cave, this level will occur when the water flow reaches a certain height of the cave. ”

"Oh. Xu Qianyun still seemed to understand a little, thought about it, and asked an idiotic question: "Then how do you know that the cave below will go up from the bottom instead of getting deeper and deeper?"

The old cow next to him slapped his forehead and said helplessly:

There are only two possible forms of karst caves, one is the fissures created by changes in the earth's crust. There is also a karst landform, which is a karst cave washed out by rain and floods. And if the karst cave is washed out, the change process must be water rushing from top to bottom, on the other hand, the karst cave formed in this way, no matter how deep, the outlet must be upward. ”

When Xu Qianyun heard this, she suddenly realized.

looked at the circle of people, but saw that almost everyone looked at themselves with a foolish gaze, and immediately blushed and was extremely embarrassed.

Just now, I was just confused for a moment, and I didn't figure out the direction of these complicated terrains.

After Lao Niu's explanation from shallow to deep, he suddenly had an epiphany, this is simply common sense.

In order to alleviate the embarrassment, Xu Qianyun hurriedly changed the topic: "Then what should we do now?"

Li Xun said lightly: "Naturally, I found another cave." ”

Xu Qianyun asked: "How can we find another cave? There are so many caves in this big mountain, do we have to search them one by one? It is even more impossible to go down from this place, this place is so deep and so dangerous, who would dare to dive down? If the entrance of the cave is bigger, it is possible for a submarine to enter it." ”

Xu Qianyun's brain hole was a little wide, and Li Xun was really a little speechless: "Who said we were going down." ”

"How can you find another cave without going down. ”

Xu Qianyun asked as a matter of course.

But this time, no one laughed at her, and everyone looked puzzled, yes, how can you find it if you don't go down? This karst terrain has been heard of, and it is notoriously extremely complex and criss-crossed. And there are many caves in the mountains, how to find them?

Lao Niu patted a soldier on the shoulder and said, "Go and take down the sonar detector on the top, I thought I wouldn't need this thing, but I didn't expect this moment to become the most important thing." ”

"Niu, Professor Niu, what does the sonar detector look like?" Probably for fear that people would be mistaken and infected by Xu Qianyun, the soldier asked with a blushing face.

"A box, about the same size as a life detector. A probe, an antenna, a display. It is written on the box, go and get it. ”

"Got it. ”

“……”

The two warriors came out of the column and hurriedly crawled up.

Moments later, a device with no features other than a display that was larger than the life detector and a few more operation buttons was removed.

Li Xun also saw this kind of high-tech instrument for the first time, and together with everyone, he looked around the old cow who was fiddling with the instrument.

But I saw that the old cow had the signal line through and after installing the wire, this operation began.

As soon as I pressed the button, I heard a screaming sound suddenly coming from the space, which was very harsh and very ugly. Everyone hurriedly covered their ears and frowned.

Including Li Xun, his brows were also furrowed, and his ears were itchy and uncomfortable.

Lao Niu explained with a smile: "The principle of the sonar detector was invented to imitate the underwater sonar principle of dolphins, and it is a very successful scientific product in bionics. This has two probes, one that emits underwater sonar and one that receives underwater sonar. The signal is sent out to propagate the sonar signal through the water in all directions. This sound travels underwater and over a wider range than it travels through the air. ”

"And sonar has a characteristic, that is, after the sound is transmitted, it will bounce when it encounters obstacles. Then, the receiving signal will use an algorithm to calculate the three-dimensional underwater terrain structure according to the continuously reflected and rebounded sonar signal. Presented through the display. This sonar detector is foolproof in this kind of water hole without running water, and the effect is accurate enough to detect a nylon rope a hundred meters away. ”

"So, it's a huge help for us to explore the underwater landscape and the direction of communication with other caves. As long as we have the structure diagram of the underwater cave and find out the direction of another cave, we can go directly to it and lock it directly. ”

Everyone was a little stunned as they listened to Professor Niu as he put two probe sticks into the water.

Li Xun also had to be convinced, now that science is developing more and more powerful, God knows how the person who invented these things came up with such a method. The use of sound to discern directions, terrain, and creatures is more powerful than the eye. After all, there are still dead corners in the eyes, but there are no dead ends in the sound.

After the two probe rods entered the water, everyone gathered at the back of the display.

But I saw that the old bull god was sitting on the ground, turned on the switch, debugged a few data, and pressed an unknown button.

After a while, a two-dimensional graph suddenly refreshed on the display screen.

This diagram is just composed of simple lines, but just through these lines, everyone immediately knows what the complex terrain and landform below look like.

Lao Niu then switched again, and the picture changed, and suddenly it became a three-dimensional figure again. The colors are distinct, blue for water and black for rocks. There are only two colors in the whole picture, only water and rocks. But there was no serpent......

The whole ground forms a 'V' shape, where the shaft is diagonally downward, then forms a loop at the bottom, and then extends diagonally upwards in the other direction.

The crowd also saw the meaning of the number - depth, 79 meters!