"Perpensing and imaging?"

"What does this have to do with yin and yang?"

Zhang Zhixiang didn't understand very much. He only knew that the shadows at noon were the shortest, and the winter solstice was the day when the sun was the longest at noon in the year. Now that the winter solstice has just passed, it should be not much different.

Now the snow is clear after the sun is bright, and the shadow of the bamboo pole is quite clear.

Speaking of which.

The ancients probably used the length of the sun to determine the two most special seasons of the winter solstice and summer solstice based on the vertical pole measurement.

"The sun shadows of the winter solstice are the longest, and the sun shadows of the summer solstice are the shortest. Do you know this?"

Zhang Baichuan took another bamboo pole, left a blank space outside the sun shadow, and then used this as the radius to draw a circle in the snow. Not to mention, it was quite round.

After his son answered, Zhang Baichuanxu lit the circle on the ground and said, "This is the earth, which is the planet we live in."

"Yeah...it's like an egg."

"In the theory of Huntian, the sun, moon and stars are all in the egg shells and egg whites, while we live on the egg yolks. The sky is round and the place is actually relative."

"Can you understand this?"

Zhang Baichuan was worried that his son would not understand such a profound astronomical knowledge, but Zhang Zhixiang was shocked that the Ming Dynasty realized that he lived on the planet!

"Can understand..."

"Well, it's good to understand. Pangu said in the opening of the sky that the heaven and earth are as chaotic as chickens. Hehe, in fact, after the heaven and earth are transformed, they are also chickens. The sun, moon and stars are all supported by qi, so they hang high in the sky."

"This is what Xuan Ye said."

"In short, Gai Tian's theory, Hun Tian's theory, and Xuan Ye's theory are the three major theories of astronomy. If you have time, you can understand it. Now, let's continue to talk about yin and yang."

As he spoke, Zhang Baichuan marked 24 scales on the circle.

Pointing to the bottom, he said, "This is the winter solstice."

Pointing to the top, he said, "This is the summer solstice, with 24 scales, corresponding to 24 solar terms."

"If you have read the "Zhoubeng Jing", it contains all records of the length of the sun shadow in the 24 solar terms. The winter solstice is 1 zhang, 3 feet 5 inches, the spring and autumn are 7 feet 5 inches, and the summer solstice is 1 6 inches, I can't remember the others, but it is roughly a gradual process."

"And during the summer solstice, on the Tropic of Cancer, which is at 23 degrees and 26 minutes north latitude, the sun shines directly at noon, and the sun shadow length is zero."

"This can also be fed back to the picture."

"The sun rises east and sets west, and there are stars."

"If you have watched the starry sky overnight, you will find that except for the North Star, all the stars in the entire star are rotating counterclockwise from west to east."

"The sky is turning, and the earth is turning."

"So, on the left side of the Winter Solstice is Xiaohan, and the solar terms are arranged in this way."

"The winter solstice is the time when the yin energy is the heaviest between heaven and earth, so at this time the yin comes from the heart and yang comes from the end. When the summer solstice is reached, the yang is the most powerful, so the next step is the yang comes from the heart and yin comes from the end. From the summer solstice, the length of the sun shadow needs to be drawn from the circle."

"We draw the length of the sun shadows of the 24 solar terms in turn and connect them..."

"Look, the Tai Chi diagram is formed."

Zhang Zhixiang widened his eyes. He never thought that the Tai Chi diagram was not realized by philosophy, but was summarized by scientific summary of the length of sun shadow!

"Hehe, are you surprised?"

Zhang Baichuan was very satisfied with his son's expression, which made him feel very accomplished as a father. Although he was a scholar, he was careless in his eight-legged articles, he read a lot of miscellaneous books.

He sat down again, drank wine and sang opera.

Zhang Baichuan is only thirty years old and has a young master style. Although the Zhang family is not a landlord, they are also rich. They have a storefront in Shangqing Town and there are hundreds of acres of fertile land.

If you have extra wealth in your family, you will naturally be free and easy.

Zhang Fu did not think that her husband was so frivolous. On the contrary, her husband was talented, easy-going and lively, and more considerate. She couldn't be more satisfied, so she looked at her husband with love.

The little maid Yushui also thinks the master is very handsome.

Da Fangfeng admired Zhang Baichuan's talent and knowledge. He looked down on those corrupt scholars who only know how to do things, but he sincerely admired Zhang Xiucai, who knew astronomy and geography.

Zhang Zhixiang was still shocked, and he murmured, "Where is the Yin-Yang Fish?"

"This...you go and ask the old master, which also involves the River Tu, Luoshu, and the Five Elements. Although I can tell you, the connection between practice is not very clear, so it is better for the old master to say it."

"Um……"

Zhang Zhixiang was a little distracted, but Zhang Baichuan didn't want to see him as a nerdy person. He pulled him over, hugged him in his arms, and said, "I've finished teaching serious knowledge, and I'll teach you something more useful."

"Come on, the rain comes."

"Anping, look at the rain. If you want to praise the rain, how should you praise it?"

Zhang Zhixiang stared at Yushui blankly. The little maid is ten years old this year. Although she has not grown up, she is a pretty and charming person. After thinking for a while, she said, "It's very clean, like the grass in spring, soft, fresh and natural."

"Yo... Not bad, and there's some talent. So if you don't know Yushui, how would you chat with her?"

"ah?"

Zhang Zhixiang probably had reacted to what his father was teaching from home. Yushui's pretty face turned red and said unsteadily: "Master!!"

Zhang Baichuan laughed: "Yu Shui, will it be good to marry Anping in the future?"

"Master, you can joke!"

He blushed and retorted, and the rain ran away, which made Zhang Baichuan even happier and continued to teach his son a unique skill. Zhang Fushi didn't stop him even when he saw it...

Zhang Zhixiang looked helpless. We are only five years old, dad.

...

After staying at home for half a day, Zhang Zhixiang returned to the mountain. The main thing is that of Dafeng. The Zhang family has no conditions to stay for him, so he can't sleep on the ground.

Before I reached the top of the mountain, I saw a little girl sitting on the bluestone steps.

She was wearing a bright red jacket, looking festive and cute, with her face supported by her hands, her little mouth was pouting high, and she was as angry as a little puffer fish, cute and ferocious.

Only then did Zhang Zhixiang remember that she seemed to have told herself yesterday that she would go down the mountain to play together.

He forgot...

"That... Dudu, didn't the imperial envoy deliver a lot of fruit yesterday? Let's make strawberry smoothies."

“Strawberry Smoothie?”

Zhang Jingdu was confused and curious, and the cuteness on his face could not be maintained, which made Zhang Zhixiang feel relieved. The origin of strawberries is also Shangzhou. Zheng He's fleet must have collected this kind of "strange flowers and plants". However, there were not many people who introduced them, but some of them must have been cultivated in the royal garden. The fruit shape of strawberries is not big and the taste is sour. He tried one yesterday and found it a bit difficult to sip.

But if you boil strawberry jam with sugar, it will be fine.

There is no industrial waste gas these days, and the snow is still very clean. Put a bowl of snow on it and pour it on strawberry jam, tsk...

(ps: Strawberries are also products of America. Whether they are proof or not, they should be regarded as the Ming Dynasty in the book. Zheng He's fleet has been to America. After all, this is a fairy tale text that exposes history. In addition, there is a Jingwei Net on the entire map of Kunyu Wanguo.)

(ps: "Medicago in Southern Yunnan" was written in 1436, and it contains records of the medicinal value of corn. "Ming Shilu" records that the price of corn in Jiajing in 5 years was 5 cents of silver per stone. This shows that in 1526, the market transaction volume was large enough and it was worth recording.)

(ps: The age of the old master was modified, and he was about twenty years older than in history. He originally had a child from old age, but in the book he changed to a young man and had a granddaughter, Xiao Zhang, who was one year old.)
Chapter completed!