On this voyage, Hong Tao left Bo Zhu at home, and only took Carl and Bo Jiao away, and the ship could not carry too many people's supplies. In case something goes wrong, he and Carl are both foreigners, and if they die, they will die, and Bo Jiao was forced up by Bo Xiaoer, he said that he has two sons, and Bo Jiao is gone, and there is still Bo Yu, don't be afraid. Since they were all so adventurous, Hong Tao also agreed with an encouraging attitude. Explore the sea, where are the immortals, if the Tan family who mixes with the sea doesn't even have the guts, then don't mix.

Before the trip, Hong Tao did two things, one was to boil all the fresh water carried on the boat in a pottery urn, and then fill it into a small jar filled with whale oil, seal the mouth of the jar and seal it with whale skin and burnt shell powder. Where the mouth of the altar is concave, it is successfully sealed, and it can be brought on board, and where the mouth of the altar is flat, it means that there is a leakage, and it is necessary to refill the hot water and reseal it.

The food at sea is easy to solve, you can bring raw rice, salted fish, dried sea vegetables and Tan's family has, you don't have to worry about eating, but you are worried about drinking. Fresh water is always in a container, and if the temperature is high, it will start to deteriorate after two days, and it will taste after a little longer. Although you won't die immediately if you drink it, it's not good for your body, and if you get dysentery at sea, there's really nothing you can do about it, and you might just die of dehydration. Although Hong Tao's method can't be said to be kept for too long, it is better than not dealing with it, and it is estimated that it should be no problem to persist for about a week.

The second thing is to go to the only jewelry store in Zhenzhou City, and ask the goldsmith in the store to create two small silver mirrors for him with the best silver quality, with scratching feet around the frame, and then fixing two pieces of natural crystal that have been ground very thin and round, these are two mirrors, the reflection effect is not bad, and the deformation is not too big. Hong Tao felt that he would not be able to burn the glass in a short period of time, let alone make a mercury mirror, so he would simply use local materials and replace it with natural crystal and polished and smoothed silver mirrors. As long as the flatness is enough, it doesn't matter if it's a little out of shape.

In addition to the small mirror, the goldsmith made him a small cylinder and two small copper boxes out of copper-silver alloy. According to his requirements, the cylinder was divided into two sections that could be unscrewed, and the threads on it were also a gift from Hong Tao to this era. The goldsmith accepted Hong Tao's patent gift with great gratitude, and refused to even accept the salary, if it weren't for Hong Tao's young age, he would have the heart to kneel down and kowtow to Hong Tao. The function of the thread does not need to be said to him by Hong Tao, with the feeling that he has been fiddling with these gold and silver jewelry for many years, he knows that it is a very useful technique, and he has obtained a craft that can support his family, and he is not wronged.

In each of these two cylinders, a piece of polished crystal with different thicknesses was fixed, and it took several changes before it was finally finalized. This is a very simple telescope, which can only be adjusted in small increments, and the magnification is about four to six times, and the number Hongtao cannot measure it too carefully.

In the small copper box is a magnetic needle sharpened by Hong Tao using a magnet and a sewing needle, and let the goldsmith fix it at the bottom of the copper box, which can be rotated freely, which is a simple compass. In addition, there are a pair of compasses and a rectangular ruler made of scraps from goldsmiths under the guidance of Hong Tao. Hong Tao didn't tell the goldsmith what it was for, and the goldsmith also knew the rules very well, not only didn't ask a word, but also took the initiative to help Hong Tao hide it from other people, until he handed them over to Hong Tao.

With these few things, Hong Tao can make his navigation weapon, the sextant. The overall structure of the sextant is a fan, to be precise, one-sixth of a circle, and a movable pointer-like grip arm is added to the center of the circle, which is called a movable arm. There will be a scale on the arc of the fan, and there are teeth on the movable arm, which bite with the teeth of the fan, which are carved by Hong Tao himself from whale baleen and whalebone. A small mirror and a telescope are fixed on both sides of the fan, and a mirror is fixed near the dot and connected to the movable arm, which is basically a complete sextant.

The mirror on the dot is an ordinary mirror, called a target mirror; The other mirror is only covered by half a silver plate behind it, which is equivalent to half a mirror and half transparent, which is the horizon mirror; Add a telescope to form a triangle, and that's a pretty good sextant.

How do you use it? First of all, you need to have a certain foundation in geometry and be proficient in using trigonometric formulas. Then point your eyes at the telescope, through the half-transparent, half-reflective mirror on the opposite side, so that the sea level coincides with the transparent half, and then rotate the movable arm in a small area, and take the target mirror at the far point to find, what to find, find the position of the sun and the star you want to observe.

When you see that the position of the sun or star emitted into the translucent mirror in the target mirror coincides with the sea level, OK, note the exact scale on the fan indicated by the center of the moving arm, which is the angle between the sun and the horizontal plane in your position. With this angle, you can calculate the exact latitude of the earth for your location based on the declination of the sun.

However, there is a small flaw in this method, because there must be shaking when using it on the ship, and the level of the sextant cannot be accurate. So what to do? Easy, you only need to shake the sextant a little to make the image of the sun that you see after two reflections swing back and forth, and when the sun is at its lowest point in the mirror, that's when the sextant is level.

But this does not guarantee that the reading will be accurate, it doesn't matter, you measure it a few more times, read the reading every other minute, and then take it, it should be more accurate. This method can only determine an approximate latitude, you can't expect it to be accurate to the minute and the second, in fact, in the case of ocean voyages, the error between minutes and seconds is not very difficult. The use of a sextant is only to determine whether the course is correct, not the target to be hit, and 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, and correct the course when you find an error, and through continuous observation and correction, you can reach the position you want to go.

In some movies, it is said that the navigator or the captain made the wrong coordinates, and as a result, the ship deviated or even lost. That's all, unless he's made a mistake for days in a row, he'll be able to react in a few hours at most. In the case of sailboats, how far has it taken a few hours? What are charts used for? Every few hours, the captain or navigator will mark the ship's position and relevant measurements on the chart, and even if the wind blows you off, it is still easy to get back to the original course with the data from the last measurement. If you have to say that the navigator and the captain don't even record the charts, that's another problem. What's the problem? You're following the wrong navigator and the captain, and they're both going to kill themselves.

So, with a sextant, a compass, a compass, a rectangular ruler, plus a route chart, a more reliable time recording tool, and the right way to use these things, you will never get lost on the seas. But then again, is it possible to sail the seas at will without getting lost?

No, first you have to make sure that your boat can withstand the rough seas and give you a chance to keep sailing. Secondly, you need to have an accurate chart so that you know where and how far away. Finally, it's good luck, in the days when there are no weather conditions and forecasts, any storm can end your feat. No matter how good the ship is, it can't withstand a typhoon, even if it is a nuclear-powered aircraft carrier, it has to avoid a tropical storm in advance, otherwise the result will be the same as a small sailing ship.

Now Hong Tao has a few of these things, such as the correct way to use it, a compass, an accurate sextant, a reliable sailboat, but it still lacks an accurate chart and good luck. He is not a surveying professional, and he has no research on what projection method, so he can only take a little measurement to measure a data, and then mark it on the chart to ensure that the places he has walked are standard and accurate. After walking like this for decades, turning around every coastline in the world, it is estimated that this accurate chart will be calculated.

Don't underestimate this picture, with it humanity has the foundation to conquer the sea. Hong Tao didn't dare to guarantee that he would be able to complete it, but Hong Tao could guarantee that it would be completed soon, because he wanted to teach this set of things to children like Po Yu, Po Shrimp, and Po Jiao, and he would also write down this set of methods in detail in the book and pass it on. As long as there are enough children like Moojiao, Moyu, and Po Shrimp, even if they are unlucky enough to die at sea, this chart will still be corrected and improved by generations of seafarers.

"Raise the sails, your parents and siblings will have endless things to say, let's not go if we continue to talk like this! Bozhu, you take the lead and get off the boat first. At the end of January, the little sailing ship, named the Explorer by Hong Tao, was loaded with fresh water, rice, salted fish, dried seaweed and coal, and set sail again. He doesn't care about life and death, but others can't do it, everyone tells him to come and go, endlessly. Hong Tao understood their feelings, but he couldn't stand the atmosphere, so he had to hug Bo Zhu and kiss her on the face, and then bombarded all the people who came to see her off very inhumanely.

"Don't look at it! Come in, and I'll tell you about the rules of this voyage. Everyone is on duty for 2 hours, and during these 2 hours, not only do you have to pay attention to the wind, currents, and ship speed, but you also have to use this thing to measure the direction, and I will slowly teach you how to use it. After the measurement is completed, write the resulting numbers on the whale skin, one for each of the three of us, each write their own, I will check at any time, how to write I will also teach you. The daily cleaning work is done by the two of you, before lunch, the food and fresh water must be quantified, Carl is in charge, and the amount of usage must be recorded every day, which is valuable data for future reference. As soon as the boat left the dock, Hong Tao called Carl and Bojiao into the cabin, and gave each of them a bamboo tube, which contained a rolled whale skin, a few dipping pens made of whale baleen, and a piece of black dye that the Li people used to bleaching and dyeing cotton cloth.

PS: Clicks, Collections, Recommended Tickets! Throw it to Hong Peel......