To Tang Feng's surprise, this lake shore was very spacious, and after Tang Feng used the strong searchlight above his head to shine through, he didn't find the edge, but Tang Feng didn't rush to find the edge, but first put the raft into the space, and then took out an M4A1 from the space, and took out two magazines, one magazine was inserted into the waist, and the other magazine was directly loaded on the grab, and pulled the bolt to load the bullet.

Tang Feng put a lot of weapons and ammunition in the space, and this thing is absolutely indispensable. Thanks to Hansen, Tang Feng didn't have an automatic rifle license, but Hansen and they did, plus Hansen was a security guard at the ranch and oil field, so Tang Feng didn't let them buy weapons from the big gun shop in Beaumont.

Tang Feng picked a lot of the weapons that Han Sen bought back and put them into the space, but they didn't use them before, but now they are used.

I have a gun in my hand, and I don't panic in my heart.

Tang Feng took out two knives, one long and one short, from the space, the short one was a paratrooper straight knife used by the American paratroopers, which was used by Hansen back then, and later given to Tang Feng, who has been kept in the space by Tang Feng. The long one is a scimitar similar to a Japanese katana forged by Bear himself, which is very sharp, and when used in close combat, it is an absolute killer.

After hanging the two knives, Tang Feng began to take dry branches and other things from the space, and then took out a small barrel of gasoline, poured it on the pile of dry branches, lit a windproof match and threw it away from the pile of wood, and suddenly, in the underground space that had been dark for I don't know how many thousands of years, a bright flame suddenly erupted.

The orange-red flames rose more than two meters high, and when the gasoline in them burned out, the large pile of dry branches also burned completely.

It's actually still relatively cold in the underground space. It's the kind that is cold and cold, but with this bonfire, Tang Feng's body suddenly feels warm.

More than three hours have passed since he fell out of the hole, and Rao is Tang Feng's physical fitness is amazing, but he can't stand such a toss. The body is cold and tired, not to mention. The key is that the nerves are tense all the time, tired!

Now that the bonfire has risen, the light and warmth suddenly made Tang Feng breathe a sigh of relief. From the space were some special torches, made for survival in the wild, made of aluminum alloy, with a container of about a liter of kerosene at the bottom, and a mass of special cotton rope on top of it. Before using it, unscrew the torch and thread the thick cotton rope through the hollow upper half of the torch. Then the lower half of the cotton cloth was placed in a container, and the two torches were twisted, so that a lamp similar to that of an old oil lamp was formed.

Lit, this torch can last for hours and is also impressively bright.

Tang Feng saw this kind of torch in a store specializing in wilderness survival equipment in Houston, so he didn't hesitate to wrap it all in one go, and there were hundreds of such special torches.

With the gun in his hand and the bonfire as the center, Tang Feng made a big circle. At intervals, Tang Feng lit a special torch and stuck it on the ground. After a circle, more than twenty flaming special torches formed a circle with a radius of about forty meters, which was enough to ensure the safety of Tang Feng in the center of the circle.

After doing these works, Tang Feng took out the waterproof mats, down mats and the like with confidence, spread them on the ground, and then took out a set of dry inner mats from the space. and a jacket. I changed out of the wetsuit on my body.

After doing all this, Tang Feng took out a few pieces of chocolate to replenish his energy, and then took out another device from the space that was not much bigger than a walkie-talkie with a small screen.

It's an infrasonic communicator that allows you to contact teammates who are also in possession of the device far away. It's just that this thing can't be used for talking, and can only be used to activate infrasound syllables in the form of Morse ciphers. The transmitter taps the letters with the keypad on the device. The reverse translator in the device turns the letters into the fluctuating syllables of the Morse code, and the receiver can restore the Morse code according to the fluctuation of the syllables of the infrasound, and then the password translator set in the device finally restores it into text and displays it on the screen.

Sound waves with a frequency of less than 20 Hz (Hertz) are called infrasound. Infrasound waves are not easily attenuated and are not easily absorbed by water and air. Infrasound waves, on the other hand, tend to have a very long wavelength, so they can diffract around some large obstacles.

Infrasound waves can travel extremely long distances, and some can even travel several times around the Earth. Moreover, the penetration ability of infrasound waves is extremely strong, whether it is steel, rock or soil, infrasound waves of a certain frequency can penetrate. For example, a 7,000Hz sound wave can be blocked with a piece of paper, while a 7Hz infrasound wave can penetrate more than a dozen meters of reinforced concrete.

It is precisely because infrasound waves have a transmission distance farther than sound waves, light waves and radio waves, and have high penetration, so the application of infrasound waves is becoming more and more extensive.

Instruments such as infrasonic weapons, instruments used to detect storms, tsunamis, typhoons, and even earthquakes are now widely used.

This set of infrasonic communication instrument is also a communication instrument that has just been developed by Bell Labs and put into market application, using the strong penetration of low-frequency infrasonic waves of a certain frequency and the characteristics of large transmission distance, and developed an instrument that can carry out long-distance communication.

This kind of instrument has not really been promoted in the market yet, but Sam has a good relationship with an executive in Bell Labs, and because Tang Feng was unable to communicate with the outside world when he encountered a mining disaster the year before last, Sam deliberately spent more than 100,000 dollars to buy such a set of communication devices.

There are a total of four terminals in this set of communication instrument, each terminal is both a terminal and an infrasonic transmitter, using the lithium battery in the device to excite infrasonic waves, and then as long as the receiving frequency of several other terminals is on the same frequency, then this infrasound wave can be received, and then restored to Morse code according to the infrasound syllable, and finally become text.

One of these four sets of terminals is in Tang Feng's hand, Sam has one in his hand, and the other is in Qiao Mu's hand, because Qiao Mu is now following Sam on Gravina Island, and the other is in the hands of the hyena who came out with Tang Feng. The reason why I bought this kind of thing in the first place was to prevent accidents, so Tang Feng and Sam had to have one set in their hands, and the other two sets had to be placed on the followers.

The reason why Tang Feng came up with this thing was to communicate with the outside. With such a thick rock, infrasonic waves may not be able to penetrate it, but the environment here allows infrasonic waves to reach the hole where they fell without any obstacles, so that they can directly contact the hyenas outside. (To be continued......)