I

Seven young people from the two houses, plus Sun Yunqiu who was called to accompany them, gathered together during the break time.

There are four Hanlin courtyards in one pile and four Qintian courtyards in one pile.

Li Quan, a sunny boy, sat down on the ground and asked, "Brother Yuan Jing, hasn't your nautical clock been built yet?"

Wang Su, courtesy name Yuanjing, was a graduate student of Jinling University and a disciple of Fang Yizhi in Qintian Academy. Majoring in physics, minoring in astronomy, proficient in mechanics, his appearance is not good.

Unattractive appearance is the key. At their age, even if they are not married, they have a marriage contract. It is really hard to find those who meet the emperor's requirements, so Wang Su, who is relatively ugly, is also pulled in to make up for it.

Wang Su complained endlessly: "Brother Yuheng, the precision you require is too high. How can I make it? It has been more than three months, and the error value of the clock has only been reduced by 3%-8%. I guess I will die of old age." That day, I couldn’t even make a nautical clock for you.”

"Try again, haha, you can definitely do it." Li Quan was not discouraged, and gave Wang Su blood with a smile.

Tian Yang said: "Brother Yuheng, if you want to measure longitude at sea, why do you have to use the clock method? Can't you use the lunar distance method?"

Li Quan shook his head: "The disadvantages of the lunar distance method are too obvious. First, it cannot be used on cloudy and rainy days, and it cannot be used during the day; second, there are always some days in each month, and the longitude measurement using the monthly distance method will produce deviations; Third, the calculation of the lunar distance method is too large, and it may be difficult for the star trainer on the ship to master it."

Tian Yang is a boring gourd in front of the princess, but he speaks very sharply at the moment: "It takes a year and a half for ocean voyages, and the first and second shortcomings you mentioned can be completely ignored. As for the large amount of calculation, we can make monthly distance Table, get out a lot of data in advance. Stargazers can use the table to calculate, which can greatly reduce the amount of calculations, and only high school graduates will be able to do it.”

Sun Yunqiu listened for a while, and asked curiously, "Are you talking about sailing?"

Sun Yunqiu is a master of Qintian Academy, while the other three are not even bachelors, but graduate students affiliated with Qintian Academy.

Li Quan still sat on the ground, cupped his hands and said: "I want to teach Master Sun that the three of us are discussing how to solve the longitude measurement during navigation. Today's maritime latitude measurement technology is very mature, but the longitude measurement has not been solved. If If a ship cannot reach the shore for a long time, it has to measure the longitude, otherwise it can only sail forward by luck.”

"Tell me what you think." Sun Yunqiu became interested.

Li Quan said in detail: "Now there are two theories, one is the clock method, and the other is the lunar distance method. First, let's talk about the clock method. According to the earth's orbit around the sun, the time of different longitudes is different. The Qintianyuan Planetarium has Set the longitude of Nanjing as 0 degrees. By calculating the time difference between the location of the ship and Nanjing, the specific longitude of the ship can be calculated."

Sun Yunqiu can also make clocks, and he shook his head immediately after hearing this: "The clock method is impossible to realize for the time being, the error is too large, and the current clocks are not accurate enough."

Li Quan said: "My idea is to improve the accuracy of clocks and watches as much as possible and build more nautical clocks. Ten or twenty nautical clocks are placed on the ship. When measuring longitude, take the average of these nautical clocks."

"No, no, you are playing luck." Sun Yunqiu shook his head.

Li Quan also said: "Then we can only use the lunar distance method. Using the position of the moon in the starry sky, the starry sky is used as a clock face, and the moon is used as a pointer. Then, through calculations, the position of the moon is converted into the time at the location of the ship. This method needs to compare the star catalog and rely on the long-term observation data of the observatory. The observation data of the starry sky is our strength, and there are hundreds of years of data in Nanjing and Beijing. But the disadvantages are also obvious. It is impossible to measure in cloudy and rainy days. The error is very large in a few days. The main reason is that the calculation is too large, and it is difficult for ordinary navigators to complete it."

Wang Su added: "The shaking of the hull also greatly interferes with the lunar distance method."

"It's not very big, it's very big, so I prefer the clock method." Li Quan said.

Wang Su said: "We plan to improve the measuring ruler and the cross to make more sophisticated navigational instruments. But no matter how we improve it, if we want to measure the longitude, we must know the position and time of the ship."

Using a sextant to measure longitude requires knowing the local time.

Europe is also thinking of ways, because their astronomical observation data is not enough, so the clock method has been used for a long time. Since the error of the nautical clock is too large, bring more nautical clocks.

But nautical clocks are precision instruments, and even in a few decades, the cost of each nautical clock will be more than 500 pounds. Twenty nautical clocks, £10,000 is gone.

Therefore, after the astronomical data in Europe matured, with the invention of the sextant, the matching "lunar distance table" eliminated the nautical clock-even so, it took several hours to calculate the longitude. It was not until 1766 that Mascarene hired a large number of "human flesh computers" to list the relationship between lunar distance and longitude, and shortened the longitude calculation time to 30 minutes.

"Are you going to explore the ocean?" Sun Yunqiu asked.

Tian Yang pointed to Li Quan: "I don't want to go, but he wants to go."

Li Quan laughed and said: "I can't stay idle, I'm going to sail around the world."

Even for voyages around the world, there are mature routes now, and it is not necessary to measure longitude. Only when traveling around the world, it is necessary to calculate the longitude in order to meet the unexpected.

Sun Yunqiu said: "I really can't help with other things. But I have an idea to improve the cross, which is to install the telescope on the cross. Well, if you want to measure more precisely, the cross will definitely not work." .If you still want to use the lunar distance method, the range of the instrument must be above 90 degrees. Then make the instrument 60 degrees, with a range of 120 degrees, why not call it a 'sextant'."

Li Quan was very interested and asked, "What is the use of installing the telescope on the instrument?"

Sun Yunqiu said: "My idea is to use a telescope instead of naked eye observation, then make a translucent mirror to make it a fixed horizon mirror, and then make a movable reflector. Turn the reflector so that the celestial body is in line with the horizon or sea level. Lines coincide. In this way, the angle of rotation of the mirror can read the altitude angle of the celestial body..."

As soon as this remark came out, the three of them suddenly became enlightened.

Tian Yang exclaimed: "How can Master Sun have such wonderful ideas?"

Sun Yunqiu said: "I often use a telescope to observe stars. Many times, I don't want to be too troublesome to calculate, and I just think of some equipment that can simplify it."

The sextant was not originally used for navigation, but for observatory observation. The concept was proposed by Hooke and Newton. Because this thing is easy to use, it was shrunk down by the navigators and taken on board.

Li Quan belongs to the kind of action group, he has to do whatever he thinks of, and he even assigned the task on the spot: "In this way, I will work with brother Ang Qi (Tian Yang) to calculate and make a more detailed lunar distance table. Master Sun and Yuan Brother Jing (Wang Su) and his team invented and made the sextant. Combining the lunar distance meter with the sextant, ocean exploration is bound to be beneficial!"

"Okay, I'll do it with you." Sun Yunqiu smiled.

Zhao Han and Li Zicheng did not go hunting, but rode horses in the racecourse.

Back now, Zhao Han smiled and asked, "What are you talking about?"

Everyone stood up and saluted.

Feng Qizhi took the lead to say: "Reporting to Your Majesty, the students and colleagues of the Imperial Academy are discussing the doubts about oracle bone inscriptions. I deeply feel that my generation is not knowledgeable enough and needs to be more diligent."

Zhao Han looked at the ground in front of them, and sure enough, he saw several oracle bone inscriptions, as well as changes in bronze inscriptions and seal inscriptions, and immediately nodded in approval: "That's right, keep up the good work."

"Thank you, Your Majesty, for your encouragement!"

The four young men from the Hanlin Academy bowed and saluted inexplicably excitedly.

Zhao Han asked Qintianyuan again: "What about you?"

Li Quan replied: "Reporting to Your Majesty, the students are discussing navigation matters. It has been agreed that the students and Tian Yang will improve the lunar distance table, and Master Sun and Wang Su will make the sextant. As long as these two things are done well, you will be in Wangyang The sea can also quickly measure latitude and longitude."

"Sextant?" Zhao Han nodded with a smile, "Very good, Dashan!"

Li Quan suddenly knelt down: "Your Majesty, the student has an unfeeling request."

Zhao Han said, "Let's talk."

Li Quan said: "I was in the Qintian Academy. I learned the stories of Magellan and other navigators from Taixi scholars. I am in the same country as China. So far, I have no navigators, let alone sailing around the world. How can the Huanghuang Dynasty lag behind the Taixi barbarians? Your Majesty, please give me five ships, equipped with experienced captains, star guides, sailors and soldiers. I want to start from Shandong, cross the ocean eastward, and first explore America for my dynasty!"

At this time, the Pacific route started from Asia in the Balintang Strait, between Taiwan and Luzon Island. Even after hundreds of years, it is the most important waterway for Japan, not one of them.

In view of the development level of Nanyang in the 17th century, the starting point of the highest quality Pacific route should be in northern Taiwan.

That's why Spain colonized Keelung in the first place. As long as Keelung Port develops, it can obtain Chinese goods nearby and ship them directly to the American colonies. At that time, Spain can even abandon Manila.

However, the Spaniards think too simply, and there are too many tricks.

First, the Han people were not allowed to help develop Keelung, so the ports and cities could not prosper, and the food needed for Keelung had to be transported from Manila. Second, due to the lack of Spanish troops, they were bullied miserably by the natives of Taiwan, and even the castle was once breached.

In desperation, Spain could only give up the colony of Keelung.

Now Spain's Pacific Ocean route starts from the South Philippine Islands and passes through Manila to the Balintang Strait. Then along the Ryukyu Islands, from the southern waters of Japan to the east, follow the ocean current to the Americas. In the Americas, it follows the ocean current, returns to the Balintang Strait in a straight line, and then goes south through Manila to the South Philippine Islands.

Luzon, Taiwan, and the Ryukyu Islands have all been controlled by China, and the Balintang Strait has almost become China's inland sea, directly cutting off the Asian starting point of the Pacific route.

In such a situation, Spain does not dare to conflict with China. In the event of a war, the Chinese navy does not need to do anything else, just block the Balintang Strait, and the Spanish galleon trade will be declared over.

Li Quan's idea was to start from Shandong and use Japan as a springboard to go to the Americas to open up a "Shandong-America" ​​route.

This route is not very useful now, but if Chinese maritime merchants want to do business in the Americas in the future, there are two routes to choose from: one is Taipei-America, and the other is Shandong-America.

Zhao Han showed a gratified expression, and asked, "Traveling thousands of miles across the sea, you will almost die, do you know the danger?"

Li Quan categorically replied: "Even though I died nine times, I have no regrets!"

This person must not be a son-in-law, Zhao Han doesn't want his daughter to be a widow in a daze.

(Thanks to Moxiu Yaolue, the lord who entered the nickname and gave the reward, thanks to the two brothers.)