Everyone brushed it all away, and Elder Niu, who was forced to stay, also mooed:

"If you talk about it, it's like my old cow doesn't exist."

They did this, and even Zhao Gongzi felt a little embarrassed.

Not to mention the small bamboo, like a blushing peach blossom.

In fact, in the past few months, although they have had a lot of contact. But the so-called competition between the boss and the second child has beaten the third child. Because Li Mingyue and Jiang Xueying secretly fought with each other and beware of each other, Xiaozhu had no chance to take advantage of it.

As a result, the two of them were more divided than when they were in the capital.

The longer he was silent, the more embarrassed he became, Zhao Gongzi coughed lightly and said with a smile: "I also know a little bit of fur, just tell you about it, and correct the wrong Uncle Niu." ”

Elder Niu turned a deaf ear and only drove his boat. The old cow was eager to find a crack in the ground to get into.

"Okay." Zhang Xiaojing nodded, and listened to Zhao Hao explain to her how the big ship used the rudder to steer, the compass to see the direction, the hourglass time, and the star-pulling board to position.

Xiao Zhuzi was distracted when he listened to it, and said in his heart that he hadn't listened to Zhao Gongzi's class for a long time.

She suddenly thought that after returning to Beijing, she could continue to listen to Zhao Gongzi talk about science at home, which seemed to be very good.

Thinking about it this way, she couldn't help but feel a little excited, and she was not so resistant to returning to Beijing.

~~

"That's it." Zhao Gongzi pointed to the needle path diagram on the table with one hand, and pointed to the pointer of the compass with the other and said, "Let's use the Danyin needle to pass the fifth watch, and then we can enter the black water ocean...... Uh, Xiaojing, didn't I make it clear? ”

"Huh?" Xiao Zhuzi came back to his senses at this time, and waved his hand with a red face and said, "No, no, Zhao Gongzi spoke very well." ”

She hurriedly calmed down and asked, "What do you mean by the five watches?" ”

Elder Niu's hand slipped, and he almost pushed the rudder out.

"......" Zhao Gongzi couldn't help but feel ashamed, and said in his heart that my feelings were all in vain.

"Is it the same as our five watches at night?" Zhang Xiaojing asked embarrassedly.

"The duration is the same. All of them divide the day into ten shifts. Zhao Hao nodded, pointed to the hourglass fixed on the slipway and said, "This hourglass is all leaked, and it is a shift." ”

He paused for a moment, and then said, "However, 'more' is still a speed unit on the ship. One is about sixty miles. Slower than that, it's called 'no more'. Faster than this is called 'over-shifting'. ”

"Then how do we know how fast the ship is, and if there is a change?" Zhang Xiaojing was completely interested at this time, and asked busily.

"Is this?" Zhao Hao looked back at Elder Niu and said, "Show Miss Zhang." ”

"Moo......" Elder Niu tried not to speak, and motioned with his eyes to the apprentice who helped him operate the pole.

The disciple picked up a plank the size of a book and ran to the bow of the boat.

Through the porthole, Zhang Xiaojing saw that he exerted a slight force and threw the plank into the sea.

With a snap, the plank landed at level with the bow.

The little apprentice ran towards the stern of the boat quickly, and Zhang Xiaojing saw that every step he took was the same near and far, and the cadence was also very fixed, just like the kind of winding soldier doll made by Zhao Gongzi, which was quite funny.

"It's hard work." Zhao Hao explained from the side: "Every time you run from the bow to the stern, the time must be the same, otherwise there will be no food." ”

"This will be able to take a speed test?" Zhang Xiaojing asked puzzled.

Zhao Hao pointed to the wooden plank floating on the sea, and smiled without saying a word.

Zhang Xiaojing saw the plank, and before she knew it, she was about to move to the stern.

She is a good student who can score 100 points in the exam, so she immediately used her brain, and in a blink of an eye, she suddenly slapped her palms and said crisply:

"I see. After the plank is in the water, it can be considered stationary for a short time, but the boat does not stop moving forward, so it is quickly thrown to the stern. If you let people start at the same time, if you go to the stern together, then you can think that the speed of the boat is the same as the speed of the person. Therefore, people have to be trained to run from the bow to the stern of the ship, which is to improve the accuracy of the measurement. ”

"Hahaha, that's good." Zhao Hao gave a thumbs up and said to Elder Niu: "How is it, my female apprentice Bing Xue is smart, right?" ”

"Moo......" Elder Niu said in his heart, it turned out to be a female apprentice. The old cow shouldn't be here.

"But Childe, what if it rains on a cloudy day and the deck is difficult to walk?" Zhang Xiaojing finally entered the state completely. "And when you want to take a speed test at night, what should I do if I can't see the clear surface?"

Elder Niu couldn't help but look stunned, he rarely sailed at night, and he didn't think about this problem. Secretly: 'If you don't have an accident, you will get it.' ’

"It's easy to want around the clock." Zhao Gongzi smiled slightly, as if nothing in this world could stump him. "You get a long rope tied to the plank and throw it down from the stern. Then, in a short time, the speed of the ship can be calculated from the length of the released rope. ”

"And it's easier and more accurate!" Zhang Xiaojing's eyes lit up, and she said excitedly: "As long as you calculate in advance and mark the rope, even an illiterate sailor can report the speed at once." ”

Now it's Zhao Gongzi's turn to be embarrassed, girl, don't you want to be so smart. Ben Gongzi just clicked, and he will rush to answer......

She really deserves to be the daughter of an idol. My idol's genes are good!

Elder Niu's bull's eyes also lit up, although he didn't understand 'distance divided by time equals speed', but he intuitively felt that this method was the same as the principle of plank speed measurement. If it was true that it could be around the clock, more accurate, and illiterate and manageable, as the two said, it would be a great improvement.

"Yes, as long as you tie a knot with the rope of equal distance, you can easily measure the speed of the rope." Zhao Hao said and smiled at Elder Niu: "I asked someone to get a few ropes like this before I came, let's try it?" ”

"Uh-huh." Although Elder Niu didn't dare to speak, he was very moved, but the cautiousness of the navigator made him dare not believe anything.

~~

So Elder Niu handed over the rudder to the apprentice, and followed Zhao Hao to the stern of the boat.

Xiwa also brought things, in addition to the speed rope that Zhao Gongzi said, there was also a circular timer.

This set of devices is the European sailors, on the basis of the Ming Dynasty's 'plank velocimeter', improved 'hourglass velocity'. They use equidistant knotted ropes to time them with an hourglass of 14 or 28 seconds. In this way, the speed of the ship can be expressed by observing the number of knots released every 14 or 28 seconds.

To this day, the speed unit of the ship is still called the 'knot'...... However, one section is equal to about 1852 meters, which is only a personal regulation, so Zhao Gongzi stipulates a section as one kilometer from the perspective of unified weights and measures.

In other words, in his territory, there will be no concept of nautical miles.

At the same time, he changed the unit of timing to 18 seconds for rounding. In this way, the distance between the two knots has changed from 23 feet 7.5 inches in the anti-human imperial system to a refreshing 5 meters.

And Zhao Hao improved the hourglass into a clockwork timer. As soon as you screw the lid of the round timer to the head, there will be a clockwork sound and the lid will turn back. After 18 seconds, the clock snapped, the timer ended, and the rotation stopped.

The structure of this thing is simpler than the mechanical doll he gave to Zhang Xiaojing, and it is a piece of cake for Zhao Shizhen, who has broken several Western clocks.

Of course, Zhao Shizhen dismantled the clock to make a gun and a clockwork timer, which was just an insignificant by-product.

ps. The fourth update, ask for a monthly pass!