There was a string of lamps in the tunnel, but Kasia didn't turn it on. The tunnels that are nearly three meters wide are flexible enough for Kasia to cope with in the dark. The sense of direction has become Kasia's most sensitive perception at the moment, and his footsteps have been kept in the middle of the tunnel, and every time he deviates from the direction, Kasia will completely note it down in his head, so that when the detection is completed, he can draw a road map that is not much different from the actual one.

Connected to an air circulation system, the sonic pulses detect some of the air transport lines. It wasn't opened at the moment, and the tunnel seemed a little dull. If a biological agent is used here、、、 while running, Kasia suddenly thinks that blending into the air can definitely achieve great results when the enemy is defenseless.

There is no doubt that the air circulation system was first built, or that no one else thought of it. I didn't say it explicitly, maybe I was still wary of my protectors. The transport team can be leaked, and they are still at the top of the organization, and in this day and age, it seems that anything can happen.

The tunnel is more or less a straight line, the angle of the curve is very large, and the sensitivity of perception is a little lower, so you may not feel this change. And in the middle of the tunnel, Kasia also found a fork in the road. The other route is of course a dead end, which is filled with a lot of sensing equipment, and the sonic pulses find their silhouette. Roughly when going to the cavity at the bottom of the route, the minecart-like movement tool is more or less prescribed by the analyzer.

I don't know if these forks are used to protect against the enemy, or to test warehouse management protectors like themselves. In the words of Adolf and the departed Five, it is easy to guess that such a task is probably a process used to add promotion justification and certainty to some elite figures. It's like when you have the opportunity, even if you just help hand over a cup and other tools, you can still hang your name on the end of some important research results.

In less than four minutes, an underground semicircular cavity with an area of nearly 100 square meters was completely revealed, appearing in Kasia's perception. After a few breaths, Kasia, who was standing at the entrance of the cave, made sure that there was no extra detection equipment around before entering the cavity.

The size of the three-story building, the track in the tunnel extends to the center of the cavity and is abruptly cut off. There was nothing but air around it, and on the side, as Five-Five had said, several fixed beams of a lift pierced the cavity from top to bottom, and two alloy safety doors cut them off, leaving only one section of the cavity included.

Kasia walked over to the security doors and looked up and down, and only then did high-frequency sound waves emit through the doors and probe the top and end of the lift.

"It is close to 100 meters up to the ground, and nearly 200 meters down to a depth of 200 meters, with three security gates in between, before reaching the bottom. "Along the shaft of the elevator, the high-frequency sound beams are consciously and slowly concentrated in one direction," and there is an unloading platform at the bottom of the shaft, as well as a simple trolley, which is also a cavity structure. A door connects the cavity, and behind the door is 、、、"

Kasia closed her eyes, and her highly concentrated spirit suddenly left her body and appeared directly under the shaft, standing in front of the alloy gate with her teeth together. The frequency of the sound wave suddenly increased by two or three layers at this moment, and entered the third stage, and completely self-analyzed the changing structure of the throat, where is the upper limit of the high-frequency sound wave, and Kasia has not yet conducted a systematic test at this moment.

As the sound beam moved, the alloy door was like a layer of transparent air, gradually fading in Kasia's head. A wide underground structure immediately appeared in front of Kasia's eyes. Just a small part, approximately fishbone-like distribution. In the many rooms, most of the equipment and machines in the application area are placed, and from the weak vibration feedback on their bodies, it can be known that most of the observed machines are in operation.

Just not seeing the researchers in the laboratory base for a while, Kasia tried to increase the frequency again, but right in front of his eyes, several glass test tubes placed on the stand burst open. As if he had been hit hard in the head, Kasia immediately stopped probing and returned to the cavity as if he had awakened from sleepwalking.

Without any words, Kasia subconsciously lowered her heartbeat and breathing, turned around and followed the original route and escaped into the tunnel. In three and a half minutes, Kasia, whose face did not change at all, returned to the basement warehouse. There was no one around, upstairs, and the other three were all doing their own thing in their rooms, not knowing anything about what was going on here at this moment.

Nothing happened, and with this feeling in mind, Kasia slowly went back to her room and sat down on the bed. After a long while, about half an hour, there was no communication sound from the communicator in his ears, and Kasia exhaled heavily: "I have to find an opportunity and time to study the changes and applications of high-frequency sound waves in the third phase." ”

、、、、、、

"Did you get the records?"

"The assistant went to print it, and he came right away. Shortly after the reply, there was a knock on the door. After a "come in" word, the door opened, and a thin man with glasses stood in the doorway, holding a three-finger-thick piece of paper in his hand, and placed it on the table in front of the three people in the room.

"Here are all the surveillance records, all converted into pictures, recorded at a frequency of every five seconds, and I chose the time period of five minutes before and after. The thin man's words did not fluctuate in tone, like a simple and cheap repeater, repeating boring tunes, "I found this in the past, but Professor Mosier." ”

As he spoke, the thin man pulled out two sheets of printer paper from the bottom of the stack, the warmth had not yet been lost, the ink seemed to have not dried up, and the smell of it instantly spread throughout the room.

"Several of the rooms there were oscillation chambers, and in each room, a piece of ultrasound recording of varying frequencies suddenly appeared on the monitor. In particular, the highest records were recorded in the test tube fragmentation room. ”

But Professor Mosier let out an "oh", took the record sheet from the thin man's hand, and asked, "In terms of time, the two should be completely overlapped, right?"

The thin man nodded, "Exactly the same." The machine we used has been inspected and there are no faults. I've also looked at the records in the analyzer, and since yesterday, there have been no records of calls and openings. I can be very sure that the reason for the tube to shatter was a sudden high-frequency sound wave, but the source of this sound wave 、、、"

"I see. But Professor Mosier nodded, "Let's go to that room and have a look." ”