Chapter 157: Wits but not strength

Su You picked up the lotus root slices on the plate: "It's hot now, and all the nutrients are used to grow leaves and flowers. Without the powder, the lotus root won't taste good. Besides, didn't you want to take this Meishan lotus root back for planting?"

Don’t you get tired of eating it every day?”

Atunmi flipped his chopsticks over and over again and muttered: "It's up to you to take care of it! How much can I eat if it's hundreds of kilograms?"

Su You persuaded her nicely: "I mean, since it's not delicious, why waste it? Wouldn't it be better to get some seasonal vegetables?"

Atunmi yelled: "Who said it's not delicious! How dare you say it's not delicious when it's so delicious?! Stop talking nonsense and come have a drink with me!"

Well, there was no common language, Su You flatly refused: "I'm a puppy if I drink with you again! I'll just drink tea!"

The two siblings were quarreling while taking off their chopsticks. After a while, the hunting team came back.

Chaogu and Shitong carried a wooden stick with a muntjac with hooves in the middle.

A'tun Chihuo had two pheasants hanging on his waist, and Li Shuan had a string of turtle doves draped over his shoulders.

Daxia Chen didn't have any prey. He had a flower crossbow dangling in his hand. When he saw Su You, he yelled: "Hey, he started eating without us again!"

Su You smiled and said, "Oh, it's been quite a harvest."

Chen Zhen said: "That's right, Brother Chao is very fierce. He shot that muntjac with his big bow. Mingrun, you really need to practice your archery. I shot a pheasant."

Su You said: "Gentlemen compete with wits rather than strength. Traps for catching prey are much more reliable than bows and arrows."

Chen Zhen sarcastically said: "You can't eat grapes and say they are sour."

Then I saw the team from the mountain returning, each with one or two pheasants hanging around their waists.

The captain walked up to Su You, took off the pheasant from his waist, and placed it respectfully on the ground in front of Su You.

The rest of the team members followed suit, with faces full of surprise.

The pheasants' wings and feet were tied with straw ropes, and they were flapping on the ground. They were all alive.

Chen Zhen didn't expect Su You to slap him in the face whenever he disagreed, so he quickly changed the subject and said to the team leader: "Ah, you guys are not serious when you are on duty..."

Atunmi chuckled: "Scholar, don't make trouble. Those are the harvests of my younger brother's hunting array. They are only responsible for collecting them when they go down the mountain."

Su You took a silk coil from a soldier and said: "This is a live trap. Birds have their own way and animals have their own ways. As long as you find the chicken hall, put a door pattern at the exit to simulate the crow of a chicken to attract them to the chicken hall.

As long as one of the pheasants is trapped and struggles, the rest of the pheasants will be frightened and step into the surrounding traps. After running two steps, the rope will be tightened around the legs, and all the pheasants will be caught alive."

Chen Zhen was greatly surprised: "Where did you learn these weird things?"

Su You smiled and said: "Don't forget that I am a country boy, and the people in the village are all good at these things!"

After saying that, he stretched his fingers into the circle and opened and closed it: "But in addition to what was mentioned above, there are a few tricks. First, the rope circle needs to be placed on a few small bamboo sticks and at a certain height from the ground; second, the seasons must be correct so that the chickens gather together.

They flock in groups and love to be active; thirdly...the rope noose needs to be thin and strong enough, and dyed in a color so that the pheasants cannot distinguish it. Such silk thread is a product of my sister-in-law's workshop and cannot be found outside."

After speaking, he handed over to a soldier: "This soldier is a hero. If he hadn't blown the bamboo whistle last night, which was exactly like the crow of a pheasant, I can't remember it, and I wouldn't have such a good harvest today."

The soldier scratched his forehead and smiled honestly.

Chen Zhen rolled his eyes and said, "I know how to cheat and cheat. Hurry up and mix the seasonings and see how you prepare dinner!"

Dinner is actually very simple. Make a soup with muntjac and add ginger and garlic. Cut the meat into thin slices and stir-fry it in the pot. Chop the pheasant into small pieces, mix well and fry until crispy. Add crispy soybeans. Not only is there a dish for dinner, but tomorrow

There were snacks for Atunmi on the way.

The rest is enough for fish.

After dinner, Su You and Li Shuanshuo began to measure the distance from the camp to the ship in the middle of the river.

The measuring tool used for the test is very simple. A needle is attached to the front of a bamboo tube. Several turns of iron wire are wound around the middle of the bamboo tube, then they are twisted together and the wire is inserted into the center of a large protractor.

Then tie the bamboo poles to form a tripod, and nail a wooden plate to the upper end to place the protractor.

Get a measuring tape, measure out 20 meters of rope, straighten it on the river beach, and nail the two ends with wooden nails.

The center of the rope is at a bamboo pole stuck in the camp.

Then put a shelf on top of a wooden peg and place the protractor so that the line on the bottom of the protractor exactly coincides with the line on the ground.

This step is very simple. Glue a piece of silk thread to the bottom edge of the protractor, screw in the small screw, and then rotate and adjust the protractor until the two hanging silk threads just touch the rope on the ground.

After the equipment is set up, adjust and rotate the bamboo tube. When the mast in the center of the ship can be seen through the round hole in the bamboo tube, record the protractor angle pointed by the pointer on the bamboo tube.

Then move to another point and record the angle in the same way.

After returning to the camp, I took out my notebook, ruler, and small protractor, and drew a miniature. After converting the angles, the problem became to know the distance between the three points on the base of the triangle, that is, the bamboo pole in the center of the camp, and the two wooden pegs.

, as well as the angle between the left and right angles, and the problem of finding the distance between the center point of the base of the triangle and the triangle.

This problem can be easily solved using the trigonometric function table, but Li Shuanshuo doesn't know how to do it yet, and the trigonometric function table has not been measured yet.

Su You turned this problem into a problem of similar triangles. He measured the length of the base of the triangle on the drawing and the distance between the center points and the distance between the center points and the base. He added the condition that the length of the base of the large triangle was 20 meters. Based on the proportional relationship, he found the sum of the campsite and the base of the triangle.

distance between ships.

This crude instrument is actually the working principle of a theodolite or collimation, and this measurement method is actually triangulation.

Of course, Su You is not pretending. As early as 600 BC, the Greek philosopher Thales measured the height of the pyramid by measuring the length of his own shadow and that of the pyramid, as well as his own height, and using the principle of similar shapes.

The distance between yourself and the ship at sea, and the height of the overhang.

In China, more than 200 years ago, the cartographer Pei Xiu also mastered this method.

Liu Hui, a mathematician at the time, proposed a calculation formula. Assume that two ships on the sea are in a straight line with the island. Knowing the distance between the two ships and the angle at which the island is observed from the ship, the projected distance from the ship to the island can be calculated.

.

This method cannot be underestimated, it is the basis of cartography.

With angle rulers, thread fine-tuning technology, bubble tubes made from glass tubes, and an observer, a simple theodolite can be built.

If you have to be more serious, all that is missing is a telescope and the earth's curvature correction formula for ultra-long distance measurements.

But even if there are no two of these, only based on triangulation, after conducting large-scale measurements and constructing a triangular network and a triangular lock, this problem can still be corrected and a very accurate map can be obtained.

Su You did not intend to do this himself. His task was only to develop the theodolite, and then hand the theodolite to the clerks of Sitong Company and their business partners for them to complete it.

In addition to data recording, a lot of mathematical knowledge is also involved here, such as square root and cube root, which are basic.

However, in today's Song Dynasty, apart from Su You, a time traveler, there are only one or two people who know this. The method of multiplication and multiplication that Su You knew was, shamefully speaking, invented by the mathematician Jia Xian at this time!

We should not underestimate the mathematical level of people in the Song Dynasty today. After Jia Xian gave the "method of unlocking the lock after establishing it", he also proposed the "method of multiplying squares to find a clean method", and gave the sixth-order Jia Xian triangle to explain the relationship between the powers.

connect.

When discussing the Pythagorean problem, we first discuss the "Thirteen Pictures of Pythagorean Transformation" and then discuss the solution to the problem. This is a completely clear system.

Such a master of mathematics, because he did not study Liu Wei's fractions and differentials, that is, the limit theory, thoroughly enough. It is more likely that he omitted the abbreviations in the book for the sake of conciseness. He was severely criticized by his junior brother Zhu Ji.

Criticism: "Abandon the remaining points, but the reason is not exhausted"!
Chapter completed!