"Dongzan came to see the horse master, but for personal friendship, not for the public." Lu Dongzan touched his neatly trimmed long beard, and smiled at me very happily, not having the depressed appearance when he handed over the letter of sin yesterday.

"Oh, not for the public?" I repeated the words of Xia Lu Dongzan, looking at the Tubo minister with a happy face and full of energy, I was very curious, could he really be an open-minded person?

"Don't believe it, although Dongzan and the horse have a lot of disputes in official affairs, however, Dongzan privately admires the style of the horse, and listens to people's words, the horse is the world's hero, and Dongzan has long had the heart to make friends with the horse. Yesterday, it was said that the business was over, Dongzan hoped to have the honor to talk with the horse master to talk about the wine, and also hoped that the horse master would enjoy some thin noodles at night, and now it was said that when the time was you, Dongzan was waiting for the horse in the Wangjiang Tower on the bank of the Qujiang River...... "Lu Dongzan patted my fart on the one hand, and invited me to eat and drink, this kind of thing, well, just right, the prince brother also wants this son to go to Lu Dongzan to ask the two Tubo girls to see the freshness, since Lu Dongzan himself came to the door, in the evening, just mention this matter, and it can be regarded as doing something for the prince brother."

"Lu Xiang rest assured, Fang Jun will definitely visit on time." Stand up and bow back. Lu Dongzan was overjoyed when he heard this, and he was overjoyed. Sent this Tibetan minister out of the door, and kept chattering in my ear about how delicious the food in Wangjianglou on the bank of the Qujiang River is, and the wine is even more mellow and fragrant, but it also came to my ear and whispered very obscenely: "I don't know, in Wangjianglou, there are several wonderful people, hehehe......"

"Hey, hey, hey......" Wonderful? Not. He hugged his fist at the Tubo who was getting on the horse and saluted: "Lu Xiang rest assured, even if he overcomes obstacles, Fang Jun will definitely be present at the banquet." ”

"Okay, a word is a certainty, Dongzan will go! Hehehe...... Drive! "Looking at the back of this old guy's vigorous back, well, this Lu Xiang's character is not bad, well, the gentleman is trustworthy, even if it is a knife, we have to meet this Lu Xiangye, of course, not to see the beauty, this, I can swear in the name of a righteous gentleman.

returned to the small courtyard, changed out of the casual clothes that he had hurriedly put on just now, took care of his outfits, and prepared to go to the concert hall, "Lu Dongzan is here for personal friendship, just to invite you to a banquet?" Sister palace maid is too wary, I smashed my mouth and smiled at the palace maid sister: "Well, but that's what I said." ”

"Childe." The palace maid raised her pretty face, stared at me for a long time, and called softly.

"Well, what's the matter?" Let the green butterfly straighten the crown on my head for me, and take the bronze mirror to see if there is anything wrong with the crown on my face. "Don't blame Zhao'er for being too careful, although Zhao'er has never seen this person, but from the news that he has heard and seen, this Lu Xiang is not such a good person. Today, I invite the prince to a night banquet, and I hope the prince will be more careful......" The palace maid sister stood suddenly, her eyebrows locked in the clouds, and her plump lips were pursed, as if she had encountered a difficult thing.

"What's wrong? Sister Zhao'er, could it be that old man from Tubo who wants to harm our young master? Green Butterfly said a little anxiously, her little hand tightened, and she almost ripped off the crown of my son along with her hair, which made me scream in pain, and scared the little girl's hands to tremble, only to realize that she had done something wrong.

"Young master, I'm sorry, Green Butterfly really accidentally ......" Green Butterfly apologized again and again.

"It's okay, just be careful, you have to tear the young master and me into a bald head, beware of family law!" Half-jokingly towards Green Butterfly. made this girl's face red, and she finally felt less guilty between her eyebrows-

took the slippery hand of the palace maid's sister, and smiled warmly at the beautiful woman who seemed to look a little gloomy: "Don't worry, Zhao'er, I never blamed you, you are dedicated to relieving my worries, if I blame you, how can I be worthy of your sincerity, that son is really a fool." ”

"Childe, I ......" The palace maid sister opened her lips lightly and wanted to speak, but she seemed to be stalked, her beautiful eyes were faintly crystalline, the corners of her mouth were slightly curled, and the joy of joy climbed up her eyebrows.

"Okay, Zhao'er, as the saying goes, I know your thoughts, my thoughts, you both understand, hahaha, General Ben will go!" Hug left and right, kiss each other, and go to work with high spirits.

When I arrived at the courtyard, I bumped into the housekeeper who was about to go out, and I found out that our restaurant in Chang'an had quietly started, well, another day, we went to our own restaurant to shop, take a look at the freshness, chatting all the way, just walked out of the door of the house, there happened to be an official hurriedly coming on horseback. Langzhong Zhonghua of the Ministry of Works, who has been in contact with me for the sand table engineering business, why did he come?

Zhong Hua turned over and dismounted before he got close, and took two steps forward with a happy face: "Zhong Hua of the Ministry of Industry has seen Fang Gongzi. ”

hurriedly returned the salute: "It turned out to be Lord Zhong Hua, I don't know what is the important thing for the adults to come in a hurry?" "Look at his appearance, is there any progress in the sand table matter?

"Five days ago, the last cartographer has returned to Chang'an from Qizhou, a cartographer of my Ministry of Industry rushed to paint at night, this morning, the whole map has been drawn almost completed, Zhong Hua specially came to Fang Gongzi for this matter to report the good news, by the way, please go to the Ministry of Industry with me to see what is missing."

"Oh?! Already done with the full picture? "I couldn't help but let out a low sigh, so efficient. As the person in charge of the mapping and sand table civil engineering project, we naturally have to go and check it out.

"My lord, please, go to the Ministry of Works first, by the way, Uncle Shen, send someone to the Jinju Academy for me to say, son, I have something to go to the Ministry of Works, if you have something important, you can come to the Ministry of Works to find me." He stepped on the horse, turned his head to the butler, and hurried away with the Ministry of Works.

There are a lot of people working in the drawing room in the Ministry of Engineering, everyone is in a hurry, very busy, Zhong Hua is currently leading the way, and walked to a large volume: "Childe, please look, this is the whole map of Guanzhong Road, just completed......" Very proud, standing next to me, waiting for me to check.

"I'll take a look, well, it's very detailed...... words of praise came out of his mouth, stood beside Zhong Hua, looked at it for a long time, and stretched out his finger: "This is Chang'an, right?" "Yes, yes, after my synthesis with many diagrammers, I already know how to use shadows to show the height of mountains. At least it won't be like the Lord's map, which is a mountain with just a pen, like a child's play.

"Gongzi Gaoming, this is Chang'an, you see, this is Bashui, here is ......" Zhong Hua's words were a lot, and his fingers kept gesturing on the long scroll.

"Hmm......" nodded as I looked at the map carefully, and I always felt that something was missing, when a cartographer passed me with a drawing. This benevolent brother, please wait a moment, can you lend me the picture in your hand? Zhong Hua didn't know why I was like this, but he just ordered the cartographer to hand over the drawing in his hand to me, and when Zhong Hua said something to me, I raised my hand to stop him. This is also a drawing, I am holding the drawing, and the drawing on the table is collated. A flash of inspiration flashed in my head, and I was so excited that I didn't know what to do, so I raised my arms and shouted: "Warp and weft!" Prime meridian! Depend on! That's it. ”

"Latitude and warp? Prime meridian? Zhong Hua and the cartographer beside him looked at me inexplicably.

"It's this thing, do you know how many miles there is in a straight line from Chang'an to Weishui?" I'm so excited that I almost don't know how to organize the language, yes, the meridian, the latitude and longitude, with the Taiji Hall of Chang'an City as the center of the division, every hundred miles or two hundred miles for a division, the first line is zero degrees, the second line is one degree, according to this draw and divide...... Complete geographical coordinates are formed, which are extremely valuable not only militarily, but also civilianly.

"Take the Taiji Hall as the midpoint, and divide the ...... in the four directions of north, south, east and west" Zhong Hua himself is a master of drawing, hearing this, his eyes lit up amazingly, he lifted his official robe and almost lay on the map, his fingers moved on it, and he muttered quietly. After a long time, Zhong Hua sighed: "Wonderful...... Childe's words made Zhong Mou suddenly open. Wait for a pen and paper to come, and ask the son to explain in detail. ”――

"Don't dare, don't dare, Fang Mou is just an accident." I'm glad that I can make Datang map drawing more accurate and intuitive, so let's be thick-skinned.

"A grid of latitude and longitude lines is called a graticule. Longitude and latitude are also known as geographic coordinates. From the Taiji Hall of Chang'an, to the east is the east longitude, to the west is the west longitude, to the north is the north latitude, to the south, then the south latitude is called, so that with the latitude and longitude and geographical coordinates, different locations, different locations can be represented by latitude and longitude. The direction can be determined according to the latitude and longitude lines, and the location of a place can be found on the map by knowing the latitude and longitude......" In front of a cartographer, this son instilled these basic theories into the minds of these people. A cadre of people listened to it as if they were drunk, and some people even wrote hard, for fear of forgetting. And I, on the other hand, continued to talk like a river, with saliva, bah! Tongue. It is the trumpet flowers of the motherland that are watered with painstaking efforts, and the seeds of science sown will take root and sprout one day!

(To be continued)