The Tiger Wing Army assesses those who come to join the army on the fifteenth day of the first month. There were still a few days to spare, and Zhao Xingde took Li Ruoxue to visit Li Rui in the bachelor's mansion.

The Bachelor's Mansion is also outside Dunhuang City, located under the cliff at the eastern foot of Mingsha Mountain, next to the crescent spring, dozens of scattered pavilions and pavilions are in the shade of the woods. Adjacent to the Bachelor's Mansion, there is a military camp of the Tiger Wing Army. There is also a private residence of a bachelor at the foot of Mingsha Mountain. It's the size of a small town.

A huge viewing platform was built on the top of Mingsha Mountain, and when the sun was setting, when Zhao Xingde and Li Ruoxue climbed Mingsha Mountain and appeared behind Li Rui, his eyes were still on the observation mirror, Zhao Xingde walked over and patted him on the shoulder.

Li Rui turned around with a hesitant face, and instantly turned into surprise. "Yuan Zhi, you're here too." Seeing Li Ruoxue behind Zhao Xingde, he bowed and said narrowly: "Mrs. Zhao." It can be seen that during this time in Dunhuang, Li Rui was in a good mood.

Li Ruoxue returned the salute with a flushed face, and looked curiously at the huge sky-viewing mirror behind Li Rui.

"Are you observing the sun?" Because it was evening, Zhao Xingde asked.

"Exactly, Yuan Zhi, you don't know," Li Rui said with an excited look on his face, "There are many black spots on the surface of the sun, flickering and changing. Li Rui pointed to a stack of white paper on the table, which was the record of sunspots he had drawn today. With his self-taught astronomical foundation and understanding, Li Rui passed the assessment of the Tianji Academy, and worshiped under the disciple of Zhou Jipu, a bachelor of the Tianji Academy, and a senior brother named Huang Shang. Zhou Jipu has been observing the stars, the sun and the moon for many years, calculating the changes in astronomical orbits, and he is now almost blind in both eyes, so he relies on two disciples to record the world on his behalf, and he dictates the way of deduction.

"It's more fun at night." Seeing that Li Ruoxue also came to the sky viewing mirror, Li Rui said proudly: "There are uninhabited hills on the surface of the moon. Rings and streaks on the surface of the star. The platinum star waxes and wanes like the moon. The stars move around the day. He sighed, "There is nothing more interesting in the world than looking at the sky." "Since entering the Tianji Academy, in addition to assisting his mentor Zhou Jipu in deducing the celestial phenomena, Li Rui has been immersed in this Heavenly Viewing Mirror almost all the time. He rejected the mansion arranged for him by the Bachelor's Mansion and chose to live in a cave closest to the viewing platform in Mingsha Mountain.

Zhao Xingde also came to the sky viewing mirror to take a look, the objective lens in front of it had been covered by a filter, and black spots on the surface of the sun could be seen. "With such a huge telescope and such a clear lens, it must be a lot of money." Zhao Xingde muttered secretly, "Why does Xia Guo spend a lot of money on this? ”

"Why is the Xia Imperial Court so interested in astronomy?" Zhao Xingde was puzzled in his heart, and asked unconsciously.

Li Rui was stunned, he just liked to study astronomy very much, and almost never considered what use it was for the imperial court.

After a while, Li Rui hesitated and said, "Maybe it's to crusade against the barbarian tribes in Mobei." The desert north of the Gobi is flying sand and rocks, vast and boundless, no matter how the terrain changes, the stars always run stably. The Ordnance Division has specially manufactured the Sky Locator. The fine function of the Military Intelligence Department This instrument can observe the celestial phenomena and accurately depict the mountains and rivers in the enemy's territory, except for the reduction of the size, it is not bad at all. As long as the expeditionary army uses this instrument to observe the celestial phenomena, even if it has never been to a place, it will know its location on the map, so as not to lose its way. ”

When he came to the simple cave where he lived in Li Rui, he saw the bed, the charcoal stove, simple clothes, books, abacus, manuscript paper with dense numbers and other things, and the walls were gloomy, but fortunately, the toilet was in another cave, and this cave was not too smelly.

Zhao Xingde couldn't help but be moved, and sighed: "Dongyan, if you talk about self-cultivation, I think you are comparable to Yan Hui." A spoonful of food, a scoop of drink, in the alley. People can't bear their worries, and they won't change their pleasures. ”

Li Rui smiled and said, "Do you think this place is shabby?" Let me tell you, just to get close to this priceless Sky Viewing Mirror, the house of Taishi Cai in Bianjing will be given to me, and I will not change it. With a look of satisfaction, he sighed: "If you live here for a long time, let me watch the heavenly phenomena every day and calculate the heavenly opportunities, and I will have no regrets in this life." After speaking, he turned around and took out some dried meat, preserved fruits and the like to entertain the guests, and seeing that he was so sweet, Zhao Xingde smiled and didn't say anything.

After a simple dinner in Li Rui's cave, a servant hired by the academy brought fresh fruits and vegetables with a winch basket, Li Rui gave him a shopping list, and the servant cleaned the cave by himself, transported the garbage and filth down the mountain, and Li Rui took Zhao Xingde and his wife to watch the celestial phenomena.

The air at night in Mingsha Mountain is exceptionally fresh. The stars and moon on the blue sky seem to be within reach. Li Rui pulled a metal connecting rod attached to the observation scope, so that the filter that was blocked outside the objective lens was removed, and then personally aimed the observation mirror at the bright moon, and after adjusting the focus, he asked Li Ruoxue to look at it first.

"I see some circle-like hills," Li Ruoxue muttered, "Guanghan Palace, where is Chang'e Jade Rabbit?" She raised her head and said a little confusedly, "I still can't see clearly." Looking at Li Rui's disappointed expression, Zhao Xingde almost laughed. Li Rui pointed the sky viewing mirror at the Tai Bai Xing to adjust the focus, and then let Li Ruoxue watch, Li Ruoxue was pleasantly surprised: "Oh, why is the Tai Bai Xing missing a piece, is it the same as the moon?" ”

Zhao Xingde smiled silently, and Li Rui was happy at this time, and explained proudly: "That's right, Venus has profits and losses, because it revolves around the sun. The size of the white is also constantly changing. This is due to the change in the distance between the star and the Earth where we live. As he spoke, he drew a diagram of the six planets revolving around the sun on a blank piece of paper with a pencil, and he also deliberately drew the moon revolving around the earth. Pointing to the picture with one hand and the starry sky with the other, he explained to Li Ruoxue why Venus has the same profit and loss as the moon.

"Because the five planets of Taibai, Suixing, Chenxing, Yingchao, and Zhenxing are all speeding non-stop, only because the sun is faintly pulling in the center, they will not fly out, but can only revolve around the sun. It's also because they're speeding so that they won't be drawn into it by the sun. In the dual-use, the cycle goes back and forth, which is the way of the stars and heaven. Li Rui sighed: "The magic of creation is breathtaking. ”

"Sure enough, it's all over the world." Li Ruoxue sighed, looked at the map of the sun and planets drawn by Li Rui, and said suspiciously, "Huainanzi said, wear a round foot square, and hold the watch and the rope." People often think that the sky is round and the earth is round, but is this earth really a round ball? ”

Zhao Xingde's eyes fell on a thick stack of manuscript paper next to him, dense data recorded detailed astronomical data for many years, and on the other piece of paper stood an equation, which seemed to divide the cube of the elliptical semi-major axis of the major planets by the planet's orbital cycle, and each planet finally obtained a constant value.

This is the eve of the great discovery, until the time of going down the mountain, the night breeze blows on his body, and Zhao Xingde still feels bursts of burning heat in his heart.

After that, for two or three consecutive days, Li Ruoxue dragged Zhao Xingde to watch the celestial phenomena, always admiring. Until the day when the Tiger Wing Army recruited sergeants, Zhao Xingde left the post house early in the morning and just came to the campus of the Tiger Wing Army, where more than 500 people were already standing.

After the selection of Mo knife hands, Zhao Xingde saw more than 30 men lined up, the tower-like body wrapped in more than 50 catties of trap armor, holding a heavy iron rod with both hands, waving up and down, each constantly hitting a log suspended by a rope, the log was extremely thick, and the impact of swaying back and forth was extremely fierce, and some people retreated due to exhaustion, until there were only a dozen or so people left, who seemed to have reached the standard, and then they were taken aside by the invigilating officer and let them use the wooden Mo knife to catch and fight, Pig and sheep bladders filled with red slurry are tied under the armor at the vital point of each person, and if the wooden knife is stabbed heavily, the red slurry flows out, and it is considered to be killed and eliminated.

Zhao Xingde stood on tiptoe to find Yu Boyan's figure, but he couldn't find it. Someone next to him suddenly beckoned, "Are you also here to participate in the election?" The man looked left and right a few times and said in a low voice, "The competition is fierce." What's your name? What blades will be used? ”

Zhao Xingde smiled and nodded, and bowed his hand: "Under Zhao De, archery is acceptable." He said politely: "Brother Tai is outstanding, and he will definitely stand out." ”

The man also bowed back and said, "In Xia Jiancheng, I am also here to recruit archers." He sighed again, "Masters are like clouds, it's hard to win." ”