This time, Hong Tao left Bozhu at home and took only Carl and Bojiao away. The boat could not accommodate too many people's supplies. △If something went wrong, he and Carl were both foreigners, and they would die if they died. Bojiao was forced to come up with Boxiaoer. He said that he had two sons, and Bojiao was gone and Boyu, so he was not afraid. Since they were all so adventurous, Hong Tao agreed with encouragement. When exploring the sea, there were no immortals. If the Dan family members who were scattered in the sea didn't even have this courage, then don't mess around.

Before traveling, Hong Tao did two things. One was to boil all the fresh water carried on the boat in a pottery jar, then pour it into a small jar filled with whale oil, seal it with whale skin and burned shell powder. Any concave mouth of the jar is sealed successfully and can be taken on the boat. Anything that is flat at the jar means that it is leaking, so it needs to be refilled with hot water and resealed.

It is easy to solve the problem of food at sea, just bring raw rice, salted fish and dried sea vegetables. Some of the family members do not have to worry about eating, but worry about drinking. Fresh water is always kept in a container. The temperature is higher and it will start to deteriorate after two days. It will taste after a longer period of time. Although it will not die immediately after drinking it, it will not be beneficial to the body. If you have dysentery at sea, there is really no way to think about it. Maybe you will be dehydrated and die. Although Hong Tao’s method cannot be said to be stored for too long, it is better than not dealing with it. I guess it should be fine if you persist for about a week.

The second thing was to go to the only jewelry store in Zhenzhou City, and asked the goldsmith in the store to create two small silver mirrors with the best-quality silver. There were also scratches around the frame, and two natural crystals that had been ground very thin and round were fixed on it. These were the two mirrors. The reflection effect was good and the deformation was not too large. Hong Tao felt that he could not burn out the glass in a short time, let alone the mercury mirror. So he should just use the materials locally and replace them with natural crystals and polished and flattened silver mirrors. As long as the flatness is enough, it doesn't matter even if it is a little distorted.

In addition to the small mirror, the goldsmith also used copper and silver alloy to create a small cylinder and two small copper boxes for him. According to his requirements, the cylinder was divided into two pieces that could be unscrewed, and the threads on it were also a gift from Hong Tao to this era. The goldsmith thanked him for accepting Hong Tao's patent gift, and he refused to even accept the wages. If it weren't for Hong Tao's age, he would have been willing to kneel down and kowtow to Hong Tao. The function of the thread is not to be said to him. With his years of fiddling with these gold and silver jewelry, he would know that it is a very useful technology. He has obtained a skill that can support his family for nothing, and kowtow is not unfair.

A grinding crystal chip with different thicknesses was fixed in these two cylinders. It was modified several times before it was finally finalized. This is a very simple telescope, which can only be adjusted to a small extent, with a multiple of about four times to six times. Hong Tao could not calculate the number that was too careful.

The small copper box is a magnetic needle ground by Hong Tao using magnets and sewing needles, and the goldsmith fixed it to the bottom of the copper box and could rotate freely. This is a simple compass. In addition, there is a compass and a right-angle ruler made by the goldsmith with scraps and under the guidance of Hong Tao. Hong Tao did not tell the goldsmith what it was for. The goldsmith also knew the rules very well. Not only did he not ask a word, he also took the initiative to hide it and prevent others from seeing it. It was not until he handed them to Hong Tao that he had an explanation.

With these things, Hong Tao can make his navigation weapon, a sextant. The overall structure of the sextant is a fan, to be precise, one-sixth of the circle. A pointer-shaped arm that can be movable is added to the center of the circle, called the movable arm. There will be scales on the arc of the fan, and there are teeth on the movable arm, which are biting with the teeth of the fan, and it is made by Hong Tao himself with whale baleen and whale bones. A small mirror and a telescope are fixed on both sides of the fan, and a mirror and a movable arm are fixed near the dots, which is basically a complete sextant.

The mirror on the dot is an ordinary mirror, called the target mirror; behind the other mirror is only half a silver plate, which is equivalent to half of the mirror and half translucent, which is the horizon mirror; plus a telescope, forming a triangle, which is a very good sextant.

How to use this thing? First of all, you need to have a certain geometric foundation and you can proficiently use the trigonometric formula. Then aim your eyes at the telescope, and use the semi-transparent and half-reflective mirror on the opposite side to make the sea level coincide with the transparent half. Then turn the movable arm in a small range and look for it with the target mirror at the far point. What should you look for? Find the sun and the position of the stars you want to observe.

When you see that the sun or star position emitted on the translucent mirror in the target mirror coincides with the sea level, ok, note the accurate scale indicated by the center of the movable arm on the fan surface, this is the angle between the sun and the horizontal plane at your position. With this angle, you can calculate the exact latitude of the earth at your location based on the sun's declination.

However, this method has a small flaw, because it will definitely shake when used on the boat, so you cannot find the level of the sextant. So what should I do? It is easy to do. At this time, you only need to shake the sextant slightly to let the image of the sun seen after two reflections swing back and forth. When the sun is at its lowest point in the mirror, it is the sextant level state.

But this does not guarantee that the reading is accurate. It doesn't matter. You measure it a few more times. Read the reading every minute and then get it. It should be basically more accurate. This method can only determine an approximate latitude. You cannot require that it is accurate to be no matter how minute or second is. In fact, as for ocean-going navigation, the error between minutes and seconds is not a big obstacle. What you need to use a sextant is to determine whether the course is correct, not the target that you want to hit. Some errors can be ignored. Generally, on a ship, whether it is the captain or the navigator, you have to observe at least twice a day. If the error is found, correct the course. Through continuous observation and correction, you can reach the position you want to go.

Some movies have been performed in which the navigator or captain missed the coordinates, and the ship deviated or even fled. That's nonsense. Unless he made a mistake for several days, he could react in a few hours at most. As for sailing, how far does it take for a few hours? What is the use of a chart? Every few hours the captain or captain has to mark the position of the ship and the relevant measurement data on the chart. Even if the strong wind blows you off and with the data from the last measurement, it can still be easily retrieved. If you have to say that the navigator and captain don't even record the chart, that's another problem. What's the problem? If you talk to the wrong navigator and captain, they both want to commit suicide.

So, with sextant, compass, compass, right-angle ruler, plus a route record diagram, and a more reliable time recording tool and the correct way to use these things, you will never be able to go on the sea. But then again, can you sail at any time without going on the sea?

No, first of all, you have to make sure that your boat can withstand the huge waves and give you the opportunity to continue sailing. Secondly, you have to have an accurate chart so that you can know where there is land and how far away it is. Finally, there is good luck. In an era without weather conditions and forecasts, any storm may ruin your feat. No matter how good the boat is, it cannot withstand typhoons. Even a nuclear-powered aircraft carrier must avoid it in advance when encountering tropical storms, otherwise the result will be the same as a small sailboat.

Now Hong Tao has several of them, such as the correct way of use, a compass, a pretty accurate sextant, and a pretty reliable sailboat, but he still lacks an accurate chart and good luck. These two things need to be explored by himself. The chart needs to be measured and drawn. He is not a major in measuring. He has not studied any projection method, so he can only measure a little bit and then mark it on the chart to ensure that the places he has walked through are standard and accurate. In this way, he has been turning every coastline in the world. It is estimated that this accurate chart will be calculated.

Don't underestimate this picture. With it, humans have the foundation for conquering the sea. Hong Tao cannot guarantee that he can complete it, but Hong Tao can guarantee that it will be completed soon, because he wants to teach this set of things to children like Boyu, Bozhai, and Bozhai, and also write this set of methods in detail in the book. As long as there are enough children like Bozhai, Bozhai, and Bozhai, even if you are not lucky enough to die on the sea, this chart will still be corrected and improved by generations of sailors.

"Shengfan, your parents and brothers and sisters will have endless things to say. If you continue to chat like this, let's not leave! Bozhu, take the lead and get off the boat first." At the end of January, the small sailboat named Explorer by Hong Tao was filled with fresh water, rice, salted fish, dried sea vegetables and coal, and was sailed again, ready to set sail. He didn't care about life and death, but others couldn't do it. Everyone told me to go there, endlessly. Hong Tao understood their feelings, but couldn't stand the atmosphere, so he had to hug Bozhu and kiss her in the face, and then inhumanely bombarded all the people who came to see him off.

"Don't look! Come in, let me tell you the rules for this departure. Everyone is on duty for 2 hours. During these 2 hours, not only should we pay attention to the wind, current and ship speed, but we also have to use this thing to measure the direction. I will teach you how to use it slowly. After the measurement is completed, write the resulting numbers on the whale skin. Each of us will write each one. I will check them at any time. I will teach you how to write them. The daily cleaning work is done by you two. After finishing lunch, the food and fresh water must be quantified. Carl is responsible for the use. The amount of use is recorded every day. These are data that are of reference value to the future." As soon as the ship left the dock, Hong Tao called Carl and Bojiao into the cabin and sent each of them a bamboo tube, which was a rolled whale skin, a few dipping pens made of whale baleen, and a piece of black dye used by the Li people to bleach and dye cotton.

ps: Click, collect, recommend tickets! Throw it hard to Hong Paihai...
Chapter completed!