Ming East India Company

The lunar distance method essentially calculates the time difference at a location by measuring the angle differences between the moon and other celestial bodies at different locations.

Since not all stars are visible in different regions at all times, the measurement of the lunar distance method involves the angular differences between the Moon and more than ten celestial bodies such as Mars, Sirius, and Vega, which requires a lot of calculation and measurement calibration.

Historically, the lunar distance method failed because the theory of universal gravitation at the time was not yet perfect. Sir Isaac Newton was unable to resolve the problem of interference between three-body motions, leading to inaccurate results. It was eventually replaced by the more accurate clockwork method.

However, Shirano is not troubled by this problem.

During my university years, I participated in a math competition with my roommates. The competition's question was to calculate the equations of the moon's motion using a classical mechanics model.

During this time, Shirano inadvertently learned something that seemed quite useless at the time—the lunar clock.

This is a complex mathematical system that summarizes the gravitational interactions between the Sun, Moon, Earth, and many other celestial bodies.

At the time, Shirano saw such a competition as meaningless, as it was simply a matter of reinventing the wheel.

By the time Tobias Mayer invented this set of mathematical results, the chronometer method had already won the longitude war. Harrison's nautical chronometer has since become the standard for measuring longitude worldwide.

This complex equation was thus shelved in the history of human scientific development.

I never expected that Shiro would come in handy today.

In the twilight sunlight of Ryukyu Island, Shirano took out his pen and paper. He had already gone through more than a dozen ink cartridges. Holding the clumsy brush, Shirano closed his eyes and began to try to recall the complex equations he had learned in that math competition.

30 periodic terms, more than 100 equations, more than 20 variables, central difference, deviation, lunar angle difference, annual difference... By the time Bai Ye finished recalling all of this, it was already dawn of the next day. Behind him were several large boxes of scrap paper and the tense gazes of the guards.

Using this complex mathematical system, Shirano can accurately predict the moon's position at every moment of the year.

But all of this is not enough.

Even the most perfect scientific theories cannot avoid errors in practice. Historically, even when Britain used more advanced chronology, it took nearly ten years to measure, calibrate, and compile nautical calendars.

Fortunately, Shirane has already developed a sextant, so all theoretical errors can be compensated for by increasing manpower for measurement.

With enough time and continuous measurement, Shirano could create a Ming Dynasty version of a nautical calendar.

Before a ship sets sail, it will receive a nautical chart. By matching the actual measured lunar altitude with the nautical chart, the ship can calculate its exact longitude at that moment.

At this point, Shiran felt he had reached his limit as a solo player, and the rest could only be left to time to correct.

Some things are destined to be accomplished by one generation, but fortunately, Baiye has many generations of descendants who can pass them on.

Baiye found Su Zhongman. During this period of "research and development", Baiye discovered that the young man had a good talent in scientific invention, so he organized the calibration of the lunar distance method.

However, Su Zhongman was only responsible for processing the later data of the lunar distance method. As for the sextant itself, Bai Ye chose two other members of the Bai family to use it personally.

In this way, those who know how to use a sextant don't know how to process the data, and those who know how to process the data don't know how to use a sextant to obtain the data, thus ensuring that confidential information is not leaked as much as possible.

……

In July of the 20th year of the Wanli reign, in the capital city, at the Ministry of War, several officials were unpacking packages from various places and taking out memorials to present to Minister of War Shi Xing for decision.

Since the outbreak of the Korean War, the usually lazy Emperor Wanli has suddenly become "diligent" and has stipulated that all memorials and official documents from the Ministry of War concerning the Korean War must be personally approved by him.

Feng Titing, the chief clerk of the Ministry of War, was selecting information about the Korean War from a mountain of memorials.

Suddenly, a senior official from the Ministry of Rites hurriedly entered the government office:

"Quickly, here are some memorials concerning the war in the East. Your Ministry of War should compile them."

The other officials present ignored him, but Feng Titing put down his work and stepped forward to speak:

"How did your Ministry of Rites receive a memorial concerning the Korean War?"

"The Ryukyu envoys came to pay tribute this year, reporting that their old king, Sho-ei, had passed away and requesting that the new king, Sho-ken, be appointed. They also presented dozens of Japanese heads, claiming them as military achievements in the war against the East, and requested verification. They also expressed their willingness to participate in future wars against the East."

Feng Titing asked in confusion:

"According to custom, foreign envoys should be received by the local governor. Didn't the governor of Fujian examine the head?"

"The Fujian governor has already reported that the Ryukyuans insist on examining the head in the capital, and they claim that it is a 'tribute' for His Majesty and must be examined by the Ministry of War personally. It is not convenient for them to stop them."

Feng Titing roughly realized what was going on:

"It seems these Ryukyuans aren't stupid. They're probably afraid that the Fujian governor, in collusion with the local garrison, will make their military achievements disappear."

"Alright, let's leave it for now! I'll submit it to Minister Shi and then make a decision."

Feng Titing took the memorial and handed it to Shi Xing, the Minister of War.

"Heh, these Ryukyuans are quite capable. They cut down dozens of heads in one go. If that's true, they could have gathered a general in my Great Ming Dynasty."

At this time, the Ming Dynasty was constantly fighting a war of attrition against the Mongols. In addition, the civil service system had strict vetting standards. Basically, being able to cut off a dozen or twenty heads in a battle was considered a great achievement that could be announced to the world and promoted to a higher rank.

"Should the Ministry of War prepare a commendation and reward?"

Shi Xing glanced at the memorial and gave a light snort:

"A commendation? The Koreans have been sending so many things every day lately, and these Ryukyuans haven't sent anything, yet they expect a commendation? Do they really think the Ministry of War is so easy to enter?"

Since Toyotomi Hideyoshi's army invaded Korea, the Joseon Dynasty has suffered repeated defeats. Now, most of Korea has fallen into the hands of the Japanese, and King Seonjo of Joseon has retreated to Uiju, waiting for the Ming Dynasty to come to his rescue.

As a vassal state of the Ming Dynasty for many years, the Koreans were very familiar with the rules and regulations of the Ming Dynasty's officialdom.

In order to get his father, the Ming Dynasty, to save him, Joseon Prime Minister Ryu Ji-ryong spent a large sum of money to bribe Ming officials everywhere, hoping they would speak well of Joseon.

As the Ministry of War was deeply involved in military decision-making, it naturally became a "hot commodity," coming and going and reaping huge profits.

Since the Ryukyuans were unwilling to offer tribute voluntarily, Shi Xing was naturally unwilling to do them any favors.