Late Ming sea owl

Chapter 74 Crossing the ocean to attract stars
That night, Lao Ruan stood on the deck of the Ganfu under the starry sky, holding a star board in his hand.

Lin Hai couldn't care less about admiring the dazzling stars that were rarely seen in the cities of later generations, and curiously looked at this ancient navigation artifact that he had heard of for a long time.

The Star Board looks like a stack of square wooden boards, with a rope running through the center of each board. The wood is made of tropical hardwood, and both the workmanship and the materials used are quite particular.Lin Hai counted and found that there were twelve wooden boards in total. The area gradually increased from top to bottom. The bottom one was about seven inches square.

Lao Ruan stood with his bare feet in position, raised a wooden board, stretched his arms and placed the board vertically in front of his eyes.He pulled the rope on the plank in front of his eyes, felt the ups and downs of the ship's hull with the soles of his feet, and looked at the lower edge of the plank when the deck was level, making sure that the lower edge was at the same level as his eyes, and then looked up at the stars.

Soon, he changed to a smaller piece of wood and repeated the operation just now.Lin Hai knew that he wanted the observed star to coincide with the upper edge of the board, so that the altitude angle of the star could be calculated based on the horizontal distance from the board to the eye and the side length of the board.

The altitude angle of a specific star can be used to calculate latitude. This is the same principle as Miguel's use of a cross skymeter to measure the altitude angle of the sun. After all, both are techniques derived from Arab sailors.This technique originally relied only on the arms and fingers and was called Qiyas. Qiyas means the height of the stars in Arabic.

Seng Yixin, a famous astronomer in the Tang Dynasty, invented a measuring instrument called the complex moment, which was mainly used to measure the altitude angle of Polaris in various places, which is the local geographical latitude.But he was not doing it for sailing, but for making calendars.

Lin Hai saw that Old Ruan was observing several stars one after another, including Polaris. After he finished his work, he asked: "May I ask Father Ruan, what is the latitude where we are now?"

Lao Ruan looked at Lin Hai in confusion: "What latitude?"

Lin Hai said in surprise: "Dad Ruan doesn't know the latitude?"

Lao Ruan shook his head: "I don't know, I've never heard of it."

Lin Hai was a little dumbfounded and asked quickly: "Then... what exactly is the star-pulling technique?"

Lao Ruan refused to tell at first, but in the end he couldn't help but Lin Hai asked again and again, and finally told him his method.In short, he still used the same formula as the needle road formula, but since there are no landmarks such as islands in the Black Water Ocean, he could only use the altitude angle of the stars to replace the mountain shape and water potential to achieve an effect similar to confirming the landmarks.

To be on the safe side, star hunting often involves observing several stars at the same time.For example, Zheng He's fleet mainly observed Polaris in the northern hemisphere, but also observed other stars such as Vega.

In the Southern Hemisphere, the main focus is to observe the Lantern Star, also known as the Southern Cross.As auxiliary observation objects, Nanmenmen II was included. Yes, it was Alpha Centauri, which later became famous in China because of a certain electrician. People at the time did not know that it was a triple star system.

In fact, Lao Ruan didn't know the altitude angle of a star at all. He only cared about the size of the wooden board and the unit of measurement he used.The smallest board is one finger, and the largest is twelve fingers. The fingers actually represent the side length of the board. One finger is two centimeters. The size of the board is made based on this.

After listening to what Lao Ruan said, Lin Hai was immediately disappointed. It turned out that the awesome-sounding star-crossing technique was actually like this. He knew it but didn't know why.In an instant, the pile of exquisitely crafted star boards seemed to have lost their halo. Aren't they just a few square wooden boards?
However, after he thought about it, he thought it was good. This method is easy to promote and anyone can learn it.If you really want to calculate latitude, you still need to know trigonometric functions, or at least be able to look up the arctangent function table, which is not much more difficult than the back-stitch formula.

Lin Hai is a pragmatist, as long as it's easy to use, the rest doesn't matter.Just like the monk who claimed to have measured the length of the meridian, in fact he didn't even know that the earth was a ball, let alone what a meridian was, but this did not affect his formulation of the Dayan Calendar that will be famous throughout the ages.You may not have noticed that as early as 4000 years ago during the Longshan period, the ancestors of Pingyang, the capital of Yao, built a magnificent observatory to guide agricultural production by observing the sun.In the eyes of these ancestors, the sun should still be a personal god. This understanding did not affect the increase in agricultural output at all.

What's more, as long as he has enough experience in looking at the stars, the team leader can definitely determine the north and south by looking at the stars.

For example, the altitude angle of Polaris directly corresponds to the geographical latitude, and there is no need to introduce solar declination for conversion like Miguel's observation of the sun.In other words, the Polaris Index seen by the team leader directly represents the north and south of the local area. If you see it more, you will naturally be able to grasp the rules.

Lin Hai asked tentatively: "Dad Ruan, do you know the north and south of this place?"

Lao Ruan replied: "Of course, walking [-] miles north from here is Chengshan. In three days we can leave the Black Water Ocean, and then walk west for half a day to reach Liujia Island."

Lin Hai has seen the nautical charts of this era. Liujia Island is on the coast of Weihaiwei, and it should be Liugong Island where the headquarters of the Beiyang Navy was located in later generations.In other words, taking the Heishuiyang route, it only takes less than five days to get from Chongming to Weihai.

This is because the Ganfu's speed is relatively slow. It traveled [-] miles in three days, which is an average speed of four knots. The downwind speed of Chinese sailboats of the same era is generally around six or seven knots.

On the one hand, this is because the Ganfu is too large, and on the other hand, sand ships generally cannot run fast.The flat bottom and square head of the sand ship limit the speed, but the higher square coefficient is also conducive to improving the cargo carrying performance. It can only be said that this is the result of optimization for the functional positioning of Beiyang cargo ships.

Three days later, Lin Hai's two boats appeared near Chengshantou.It is located at the easternmost point of the Jiaodong Peninsula. Before Qin Kai, the general of King Yan Zhao, occupied the Liaodong Peninsula, Chengshan was the easternmost place in ancient China. Therefore, pre-Qin legends say that this is the residence of the sun god, and that Emperor Qin and Emperor Wu of Han once visited here.

After passing Chengshantou, the Bowang and Ganfu did not go west to Liujia Island as Lao Ruan said, but instead went to North Korea in the northeast.This is a route that has never been traveled before. It sails roughly along the dividing line between the North Yellow Sea and the South Yellow Sea. It is a straight line selected by Lin Hai based on the map.

The sea route to North Korea in the Ming Dynasty started from Dengzhou, crossed the Bohai Strait along the Miaodao Islands, then went north along the Changshan Islands on the east side of the Liaodong Peninsula, and landed at Xuanshapu north of Pi Island.This waterway is winding and long, covering a distance of more than [-] miles, while the Linhai route only takes [-] miles to reach Jangsanchuan in North Korea.

After arriving at Changshan Chuan, go north along the coastline of West Korea Bay. It takes about two days and nights to reach Phi Island.Lin Hai's two ships separated after arriving in North Korea. The Ganfu continued to sail to Pidao, while the Bowang stayed at Daqingdao near Changshanchuan.

　It is clear that it can be abandoned, but the world cannot abandon it.I recommend a book about unsystematic farming written by a late Ming Dynasty writer who is a big fan of Ke Shanmeng.

　　


(End of this chapter)