After dinner, Zhou Yun wiped the sweat from his head and said, "I can still sweat so much in November, which makes people feel so comfortable."

Tan Weixian said: "Please help me with something?"

Zhou Yun smiled and said, "I knew! Delicious foods come at a price. What can stump you?"

Tan Wei talked about the situation first, and Zhou Yun stopped laughing immediately.

"Have you brought the stuff?" Zhou Yun asked.

Tan Wei first handed Zhou Yun a bag in his hand. Zhou Yun took it and said, "I will meet you at this sweet potato store tomorrow afternoon, and I will give you a letter!"

After the two separated, Zhou Yun returned to the military camp.

After entering his room, Zhou Yun habitually reviewed the surroundings.

This is a small house with an area of ​​only a dozen square meters. It is a single room where the main official lives.

The soldiers lived in large houses, which were hundreds of square meters in size.

After reviewing, Zhou Yun sat down and sat next to an old table.

I took out the small bag and found that there were three stacks of telegram scripts tied together.

Each stack is a telegram sent by a channel and a transmitter.

Sandist is the telegram sent by three transmitters and three transmitters.

Zhou Yun untied one of the stacks of telegrams and started reading.

However, he still couldn't understand the direction of the password.

There was no choice but to turn to Xiaofen.

It took ten energy points to unlock a password source. Once the password source is solved, the telegrams will be much easier. Of course, this is easy for small points. If Zhou Yun does it, it will not be able to get it out for half a year.

Xiaofen told Zhou Yun: "This is a new cryptobook composed of a normal public cryptobook in Japan, which adopts the method of advancement, three retreats, and two retreats."

Advance three and retreat two means that each number produces another arrangement and combination on the original public cryptography. Advance three means that the number is greater than four and includes four and adds three on the original basis. If two and add three, it becomes five. If two and retreat two means that the number is greater than five and includes five and subtracts two on the original basis. If seven, subtracts two and becomes five.

If the digital is 8416, and the law of advancing, three retreating, and two, the digital becomes 6744. Then use the Japanese public cryptobook to translate the words.

Thirty telegrams, the small number was translated in less than five minutes.

This is a marking point for the military important places in Chongqing. Zhou Yun couldn't understand it at first, but after thinking about it for a few hours, he thought of something. He immediately found a map of Chongqing.

This is a map of Chongqing published in the 27th year of the Republic of China. Twenty-six years later, Chongqing became the capital of the capital, with very rapid development and great changes. Therefore, the original maps vary greatly.

The new version of the map basically marks all units and military facilities of the National Government on the map. It is the most accurate map at present.

From the telegram sent by Rite, the map mentioned indicated that it is March 8. The number cannot be thirty-eight years. The Republic of China calendar was eleven years less than the Gregorian calendar. If it was thirty-eight years of the Republic of China, it would be 1949.

Expanding the map, Zhou Yun stared at the map for half an hour. What is the number on the telegram? The longitude and longitude? Not like it,

Latitude and longitude are the combination of longitude and latitude to form a coordinate system, called a geographical coordinate system. It is a spherical coordinate system that uses the sphere of three-dimensional space to define the space on the earth, and can indicate any position on the earth.

Latitude lines, like longitude lines, are auxiliary lines assumed by humans for the convenience of measurement, and are defined as the trajectory formed by a certain point on the earth's surface rotating with the earth.

The meridian is also called the meridian. Like the latitude line, it is an auxiliary line assumed by humans for the convenience of measurement. It is defined as a semicircular arc on the large circle line connecting the north and south poles on the surface of the earth.

It is also easy to determine the longitude and latitude line.

At any location on the earth, as long as there is only a table, a bamboo pole, and a tape measure, you can know the local latitude and longitude. However, the table must be proofread with the country's standard time.

Zhou Yun went out immediately, called Fangyan, and asked a few people to help. He worked hard all day.

First, Zhou Yun calculated two minutes of day.

For example, in Chongqing, where Zhou Yun stands, the shortest time of the pole shadow is 13:20 noon, and the ratio of the pole length to the shadow length is 1, then it can be seen that the place is 31° north latitude (tgα=1), and 109° east longitude (15° from 120° for 1 hour, 1° for 4 minutes). The ratio of the pole length to the shadow length needs to be checked for α, where α is a special angle.

Then calculate the algorithm for the longitude of the two to the sun, and the constant latitude of the winter solstice α23.5° in the northern hemisphere, and the summer solstice α-23.5° in any day, just add or subtract the correction value.

Correction value algorithm: the difference between the days from two minutes or two days is multiplied by 94/365. For example, on November 2, 1938, the winter difference of 8 days on November 8, 1938, that is, the direct sunlight point is 33×94/365=8.5°. So the latitude obtained at noon today is (arctgα8.5)°.tgα=pole length/shadow length.

In this way, as long as each latitude and longitude in Chongqing is accurately measured to 0.1', the Chongqing map can be differentiated into hundreds of coordinates.

For example, 105°19' east longitude and 28°13' north latitude, it is the building of the Ministry of National Defense.

The Japanese must have printed Chongqing maps, exactly the same as those in Zhou Yun's hand. In this way, as long as the Japanese issued coordinate numbers, the Japanese army would send planes to carry out targeted bombing.

Of course, because the bomb devices used by Japanese fighters are simple, they do not have airborne navigation devices or propulsion systems like missiles from the 21st century. These bomb devices are accelerated only by gravity and inertia, and are navigated through the driver's manual aiming.

The Japanese bombers are divided into three types: dive bombers, high-altitude bombers and torpedo bombers.

Diving bombers are the biggest threat faced by the national army. Bombers are fishing down from the sky and dive sharply towards the target. When the aircraft is only a few dozen meters away from the target, the pilot presses the button to drop the bomb. The bomb is fixed on a rack or track through a simple locking mechanism. After the lock is opened, the bomb will slide down the track or fall from the rack. If the pilot has the opportunity to drop the bomb, the bomb will hit the target instantly after the aircraft turns and leaves. When the bomb hits the target, the detonator of the warhead ignites a small amount of explosives, and the small explosion generated triggers a large number of explosives in the bomb, thereby detonating the bomb.

Under this kind of bombing, the Chinese army suffered heavy casualties!

The operation method of high-altitude bombers is very different from that of dive bombers. They fly directly above the attack target, then drop a large number of bombs, and carpet bomb the entire area. This type of bomb also uses gravity as propulsion and does not have any navigation devices.

This is the main force of Japanese bombers that carried out large-scale bombings in Shanghai, Nanjing, Wuhan, Changsha and Chongqing.

The bombs dropped by torpedo bombers have both propulsion systems and navigation devices. Torpedo bombers are very effective in air-to-sea combat. Like dive bombers, torpedo bombers also need to pounce on the target, but they drop bombs when they are far from reaching the target. This type of bomb (a torpedo, similar to the torpedo launched by a submarine) accelerates toward the target in water.

In Zhou Yun's memory, six years later, the Japanese Navy used this torpedo bomber to carry out indiscriminate bombing on Pearl Harbor.
Chapter completed!