For example, even if it is placed in the 21st century, it is also very large Beijing-Hangzhou Grand Canal, which took about 10 years in the Sui Dynasty to basically run through, which is still the result of turmoil and lack of funds.

It sounds very incredible, but in the feudal era, when the power of the entire dynasty was concentrated together, it was very terrible, even if it was a very important canal in the entire history of China, which directly benefited the Tang Dynasty and the Song Dynasty, but it dragged down the Sui Dynasty, and Emperor Yang of the Sui Dynasty, who was so happy, finally lost his throne.

Epoch-making projects are almost inevitably huge investments, and in the dynasty, they are only one aspect, and when there is not enough investment, they can only be filled with human lives.

History is written by the victors, this is not false at all, some emperors who have lost the throne, they do ridiculous things, sometimes, in those founding kings, even where the Ming monarchs, will also appear, the winner is the king, there is nothing wrong with this, in the continuation of the dynasty, these mistakes are diluted, or even whitewashed, and the king of the dead country, in a series of history books, deliberately or artificially increased a lot.

The same is true for the Dinghai Navy to draw the longitude and latitude map now, and it is also a huge number of people mobilized, but the only difference is that it will not oppress these people, but will use huge manpower and material resources to promote this.

The current Dinghai Navy is not the same as more than a year ago, the Dinghai Navy at that time was just a small island with a population of only a few hundred households, and it was extremely poor, and the fishermen relied on fishing for a living, but after the arrival and change of Zhao Xin, it has formed the largest city in the Northern Song Dynasty at present, coupled with rich commerce, there are many forces that can be used.

Astronomy, even after a few hundred years, is something that a few people can study, the earth is round, and it will eventually return to the point of view if it moves in one direction, and this point of view is really beyond imagination, so that people in this era can understand this, it is not just casual talk, or teaching can be done.

Of course, Zhao Xin can't let these people understand astronomical measurements and astronomical data, all he wants is the results of this measurement, as long as he makes this measurement tool, uses a unique tool, in a specific time, to measure the sun's rays, and then record the angle.

This is just a simple tool to use, as long as you try a few more times, and then record it, the most accurate results, you can even record multiple results, and then let Zhao Xin choose.

In fact, this is the use of tools, which is different from understanding tools, a gun, even if it is placed in the hands of the ancients, as long as someone teaches them, even if they don't understand what secrets are in the gun, they can take it out and use it.

In this way, the huge work is handed over to Zhao Xin, and these data must be sent back, and then Zhao Xin will use some formulas to calculate the general laws in this formula, and then apply them to the charts.

Zhao Xin knows not a lot of things about latitude and longitude, but fortunately, he remembers some fixed latitude and longitude coordinates, although in this era, the coordinates of longitude have changed, and the position of the coordinates can be different, but the difference in distance is the same.

Zhao Xin sent a huge number of people to measure some important ports, important cities, and some other points, and even, because of the relationship of self-driving travel, he has also been to several scenic spots, although these cannot be used as first-hand data, but can be used as a reference.

Weights and measures in this era are far from being able to accurately measure, and many distances and the like are estimated rather than measured by laser ranging from satellites. The two are referenced, plus the difference in angles, and finally, the distance between latitude and longitude is calculated.

In fact, Zhao Xin also knows a data, that is, the longitude line was about 111 kilometers at one time, and the dimensions above the equator were also 111 kilometers, but with the rise of the latitude line, his distance will gradually shorten.

This is actually a function on a sphere, Zhao Xin's own knowledge below high school, are quite solid, this may be a little more outlined, but it can be reduced by some things, this is not to calculate all the data of the sphere, but only a side length problem, there is a fixed point, and a fixed side length, it really doesn't work, find a ball to measure, for the outstanding craftsmen of the Song Dynasty, it is not difficult to carve out a ball with pure hand.

In the era of the Northern Song Dynasty, it was not an easy task to derive some formulas for spheres, especially when the existing data were not very complete, even if it was Zhao Xin, a lot of brain cells were wasted.

Zhao Xin will not be all accurate, for the laser ranging map of later generations, the accuracy of some things is almost accurate to centimeters and millimeters, which is under the premise of leading technology.

But do you really need such an accurate map, a map of the city, for ordinary people, a rough is good, not to say that it is accurate to centimeters, or decimeters, even if the error is more than ten or twenty meters, it will make people find the wrong direction, people can look around.

Charts are very important, an accurate chart can help ships sailing on the sea to reach their destinations quickly and not lose their way, and this error is not as small as imagined.

Sailing on the sea, the lookout is an indispensable post, on the high mast, there will be a special place to watch, and even some large ships, will be set up several.

This lookout is to ensure the safety of the ship's navigation, and also to detect some dangers or islands earlier.

Human eyesight is limited, even in the daytime, according to the standard that the earth is round, a person with a height of 1.2 meters, at most, is two or three kilometers, but with the increase in height, the range of vision will be extremely increased.

During the daytime, on the sea, under the premise of no obstruction, the field of vision is very far, and the average lookout with good eyesight can see large objects at least 10 kilometers away, for example, a ship of the same size, if you add a telescope, you will see farther.

The high mast used by the sea ship not only increases the area of the sail, as long as the mechanical balance is balanced and the center of gravity is lowered, the seaworthiness will not be strong because the mast is too high, but the higher mast brings a longer lookout distance.

Some excellent telescopes can even see 20 or even 30 kilometers away, which greatly increases the error tolerance of the chart.

Not to mention further, simply 10 kilometers, has made the error can be large to a certain extent, even if it is a manual measurement, with the current weights and measures, as long as a certain degree of accuracy is maintained, it is impossible to have an error of more than 10 kilometers, even if it is 1 mile, it is already a very large error.

At sea, it is even less, because there is no obstruction, there is no detour and so on, as long as you find a suitable measurement method, you can reduce the error to a certain extent.

At present, the formula used by Zhao Xin is not necessarily the latitude and longitude, the most suitable formula to use, for the determination of distance and angle before two points on the sphere, it is not very accurate, the error of this measurement can be controlled, only when a long distance is measured alone, this error will accumulate to unbearable.

However, the lowest unit of latitude and longitude is degrees, and it can even reach seconds, that is, one-tenth of a degree, not to mention seconds, even if it is an error between degrees, at best, it is three or five kilometers.

There are many ways to set up a lighthouse in this arrangement, for example, a lighthouse in the harbor, in the daytime, the huge lighthouse is a huge reference, and at night, the light of the lighthouse will guide the way of the ship in the dark night, and even some unique signs and lights will tell the ship which port is here.

These were originally things that Zhao Xin ignored, but now he thinks about them because of the charts, to put it bluntly, sometimes, things that seem completely useless, in fact, are gradually accumulated over hundreds of years, or even thousands of years, the ancients did not understand science, but they understood, a certain thing, or a certain solution is correct or not, these things are very practical.

In short, in terms of navigation, nautical charts are not all, there is no perfect port, there is no systematic layout, and a simple nautical chart cannot be convenient and fast navigation.

The construction of the port, especially the lighthouse, has begun to be built, and there are four lighthouses at least 40 meters high in different positions of the navy, these lighthouses are different from the fortresses, and there is no need to consider the problem of defense, and even the construction is very large, but there is one point, how high how to come, how to eye-catching.

Unlike the fortress, which must take into account the surrounding environment, there is no obstruction, there is no stealth, the first task of the lighthouse is to be high, that is, to attract attention.

The lighthouse currently chosen by the Ding Navy is mainly on the seaside, the highest location, the Ding Navy is a rocky island, so on the side of the port, there are still some hills that are a little higher, choose a lighthouse with the best view, the closest to the port, a peak about 170 meters high, and build a lighthouse with a net height of 70 meters.

When the highest fort is more than 20 meters, 70 meters is a bit too high, but in the Northern Song Dynasty, and even earlier in the Han and Tang dynasties, after Buddhism was introduced to China, the tower has appeared, and the highest wooden tower is close to 70 meters, and the tower of pure masonry structure is even more than 80 meters.

The reason is very simple, the structure of the tower is narrow, the narrowest tower, the interior only accommodates a person up and down, among the structures, the narrow structure, the highest strength, even if it is laid with masonry, even if there is no adhesive such as cement, it can be built quite high.

Now that the Northern Song Dynasty has cement and steel bars, 70 meters is just a not too high number when building such a tower-like building.

There is no need to build too high, and it is not necessary to build a TV tower, the tower of unique shape, at a height of 150 meters, is already quite eye-catching, with a telescope, it may be thirty or forty kilometers away, you can clearly see, there is no need to build too high, too high, has exceeded the limit of the optical telescope.

A similar arrangement, in the future, in various ports of the Northern Song Dynasty, will also be arranged in this way, which is an indispensable arrangement, which can make the future ocean voyage more tolerant.

Zhao Xin's status as a naval envoy is very high, this is almost a status with various transfer envoys, but his identity is to the Ding Navy, and he has no jurisdiction over those ports, but Zhao Xin does not want to control them, let alone for some ulterior purpose, just to facilitate navigation.

As long as the navy is set to pay for the construction of some auxiliary buildings suitable for the port, and the navy is given money and does not enjoy jurisdiction, is there anyone who is unwilling to do this?

It takes time to build, Ding Navy must slowly let this lighthouse prove its effect, for the time being, it can only be implemented in places with enough influence, and it will take time to improve, the plan has been promulgated, and the money is basically in place, but to complete the construction, there is no way to complete the construction without a few years.

For the time being, we will improve the port and the landmark buildings by the sea, so that even if there is no lighthouse, it will be possible to draw charts and sail through these landmarks that have been recorded.

After the action force of the Dinghai Navy was very strong, after starting to measure the latitude and longitude, soon, some nearby coordinates were fed back, for example, Haizhou, as well as some ports extending around, as well as those ports that were closer to the Dinghai Navy.

Even if these coordinates are not accurate, Zhao Xin will measure the surroundings according to some formulas and data that have been produced, at least to ensure that the ships going out for sea trials will not lose their way and can facilitate a wider range of sea tests.

The latitude and longitude of Lianyungang here need to be re-measured, according to Zhao Xin's understanding in his previous life, it must be more north than the Tropic of Cancer, but how far is it, there is no accurate number, and it feels like it should be in thirty or forty degrees.

If you are not in a hurry, you can take your time, the two latitude lines recorded by Zhao Xin are the zero parallel of the equator, and the 23.5 parallel of the Tropic of Cancer.

Then, through the relative distance and position, the fixed longitude and latitude indicators are determined step by step, and the data obtained at that time is more accurate.

Now, just a rough data, in Zhao Xin's feeling, it is between 30 degrees and 40 degrees, and between 30 and 40, Zhao Xin chose a 35.

It seems that there is some haste and some errors, but he is not currently sailing in the ocean, nor is he looking for a new continent, but only to determine the origin of a coordinate.

The function of the sextant is just to set the angle of the sun's rays according to the two points before, and even two opposite points, even if the point is set to zero degrees of longitude and latitude, and then the relative coordinates are obtained, the distance between them will not be many problems, as long as the longitude and latitude, the distance between each degree comes out, it can be.