How to accurately draw a topographic map of mountains and rivers, craftsmen nowadays, their own methods.

The Mo family is the master of the collection. It was not until the Wei, Jin, Southern and Northern Dynasties that the Momen notes scattered in many pre-Qin and Han dynasty documents and historical materials were sorted out and recorded by later generations and were able to see the light of day.

During the Wei and Jin dynasties, there was Pei Xiu, and when summarizing the drawing experience of his predecessors, he found a lot of beneficial methods. Therefore, the methods of each family were summarized and sorted out, and the "six bodies of cartography" were proposed. Creatively summarize the six principles of mapping. They are: Score, Quasi-Wang, Daoli, Superior, Fang Evil, and Straight.

And according to this method, he personally completed the surveying and mapping of the "Yugong Geographical Map". This is the earliest "Atlas" in China.

"Fraction" is the scale, "Quasi-Wang" is the direction, "Daoli" is the distance, "Gaoxia" refers to the height difference, "Fangxi" is the slope, and "Straight" is the conversion of height and distance.

Pei's cartography accurately clarified the relationship between map scale, orientation and distance, and had a far-reaching impact on map surveying and mapping in later generations.

At the same time, there was also Liu Hui's "Island Sutra". The "gravity difference method" is used to measure the topography and landform at sea. It also provided a mathematical basis for cartography, and was the earliest work of "Surveying Mathematics" in China.

Later, Tang Seng "a line (Zhang Sui)", using self-made "zodiacal travel instrument", "water transport armillary sphere" and other large-scale astronomical observation instruments and demonstration instruments, along the same line in the north and south of the Yellow River Basin, selected a number of measurement points, respectively measured the height of the North Star at each point, and the ground distance between any two points, and calculated the length of the meridian.

The conclusion is that the difference in the height of the North Pole is one degree, and the difference between north and south is 351 miles and 80 steps, which is the length of the meridian (131.3 kilometers). Compared with the meridian accurately calculated by later generations (111.2 km), although there is an error of 20 km (the error rate is only 0.18), it is still accurate. Therefore, he is said to be the first person in the world to "accurately measure" the length of the meridian.

In a word. The altitude of the North Star is the local geographic latitude. Just know the difference in the altitude of the two North Stars, that is, the difference in latitude between the two places, from which the meridian length can be obtained.

On the other hand, if you know the length of the meridian and measure the difference in the altitude of the two North Stars, you can accurately determine the difference in latitude between the two places.

The significance of this result is self-evident.

For later generations, mapping and mapping also had a far-reaching impact.

First of all, the North Star is not moving relative to the North Pole, and the elevation angle of the North Star is the local geographic latitude, so it has nothing to do with the measurement season (please note).

Secondly, the meridians are equal semicircles, spanning 180 degrees (180°), so the shape of the Earth does not affect its measurement (note again).

Just look up at the North Star on a clear night. By accurately measuring the elevation angle, the difference in latitude between the two places can be accurately calculated.

Whether "Sinan" is a compass in the true sense of the word, later generations have not been decided. However, since Liu Bei's "unicorn came into the world", the compass has indeed appeared. All Jiguo sea ships are equipped with a "needle room" for the placement of "Sinan". Liu Bei has ordered Su Bo and others to develop a "navigation compass". Materials such as compass, white glaze, and other materials are complete, as long as the physics contained in them are integrated, the nautical compass is born, it should not be difficult.

Nowadays, the compass is called "栻pan". It is mostly lacquered wood. It is similar to the "Feng Shui Compass" of later generations, consisting of a round heavenly disk and a square ground plate. Twenty-eight Pleiades are engraved on it. The four corners of the ground are connected with the heavenly plate, and the four corners of the ground are connected with the heavenly plate, embedded with one large and two small, three bamboo beads, which are used for rotation, and the structure is complex and exquisite.

With a little modification, it can be made into a nautical compass.

And before the advent of the "nautical compass". The ancestors used the stars to identify directions.

According to the "Hanshu Art and Literature Chronicle", in the former Han Dynasty, there were 12 volumes of "Star Astrology in the Sea" and 22 volumes of "Miscellaneous Things of the Five Stars in the Sea", totaling 136 volumes. All of them are the astronomical experience and laws summed up by the predecessors at sea. Record the position judgment of constellations, planets, etc. during navigation to determine the route.

However, passing through the sun or constellations, only the course can be determined, and the precise positioning cannot be made. It is impossible to determine the speed.

As for "pulling the stars across the sea" and "throwing ropes to count the festival", these are all later words. There is no need to sail the ocean these days. The Wakoku archipelago and the Samhan Peninsula are separated by the sea. As long as you cross the Tsushima Strait, even if you encounter hurricanes and ocean currents, you will eventually be able to find the Yamatai Kingdom with the narrow length of the Wakoku archipelago.

Just at the port of Tsushima Island, as a relay. The ships can travel to and from the Samhan Peninsula and the Wakoku Islands via Quanzhou Port, Namjin Port, Jeju Port, Busan Port and Tsushima Port. Calculate the time, and the fleet heading for Yamatai will return in a few days.

Thanks to the fact that King Ji was a teenager, the mapping and production of Lou Sang miniature model maps.

The craftsmen of the thistle country can accurately draw maps in the unit of "one side".

"Vertical and horizontal" is called "one side". This is the provincial name of "one side of the zhang". In other words, reducing the "one zhang" to "one inch square" is the most commonly used city drawing "fraction" in the Ji Kingdom.

It is what the craftsman said: "The soil of one side is shrunk between square inches".

The king of thistle has already spoken first. All the maps and nautical charts of the country of Ji are based on "one mile square". So, in the square of "one inch square", a one-mile sea chart was drawn. It is one of the king's orders when all the ships of the Thistle Kingdom go to sea.

How to calculate the speed has become an unsolved mystery haunting the heart of the thistle. In Liu Bei's view, the reason why the speed of the ship is difficult to calculate is that the relative speed of the ship cannot be calculated in the vast sea. Unlike land, seawater is fluid.

Knowing that Liu Bei was at a loss to measure the speed, Zuo Guoling said: Why not use the "Driftwood Method"?

Liu Bei was stunned: Come quickly.

The "Driftwood Method" is the "Maritime Metering Method" first created by the Chinese ancestors. This method, no later than the Han Dynasty, has been applied to nautical activities.

According to the Three Kingdoms, the Eastern Wu people Wan Zhen "Nanzhou Foreign Matter Chronicles" contained. The specific operation of the driftwood meter method is as follows: one person throws the wooden block into the sea at the bow of the boat, and the other person runs to the stern at the same time, to ensure that the "man and the wood" reach the stern at the same time. In this way, knowing the length of the hull and the running time, the speed can be calculated, and then the range can be calculated.

There are two keys to this: first, to set off and arrive at the same time; Second, it is necessary to be able to keep accurate time. If you use something like "a stick of incense", it is obviously too coarse. It is also difficult to calculate the "difference between minutes and seconds" with missing moments.

The high priestess, who was delicate and tongue-in-cheek, was also in the midst of her busy schedule, and said with her face up: Why not use an hourglass?

A word wakes up the dreamer.

The hourglass is not complicated. It is much the same as the current leakage carving. As mentioned earlier, white glaze and fine sand grains are brought at hand. It's not complicated to make! The hourglass is easy to carry and is not limited by geography. For example, the north is cold nowadays, and the dripping water becomes ice. It cannot be used outdoors. And it is not limited by water pressure, and the hourglass is more accurate than the leaky engraving.

After unlocking the glaze firing, many creations came into being.

A glimpse of the whole leopard. Let's see, what is the combination of East and West! Western tricks also have great ingenuity. Of course, the learned high priestesses also contributed to it.

The thistle king has always been rewarded for his merits.

He hooked up his hand and carried it into the poolside hotbed.

"In front of the back courtyard of the jade tree, Yao grass makeup mirror. Last year's flowers are not old, and this year's moon is full. Mo Jiao is biased, and the moon and flowers, the heavenly sect is a young man. ”

。 Nine Heavenly God Emperors