Reading lenses are not as demanding as the lenses of telescopes, with a large focal length and thin lenses. Pen @ fun @ pavilion wWw. ｂｉｑUｇE。 info Relatively speaking, it is much easier to grind, even if it is done by Qiu Zhizhao's apprentice, it has been grinded out a lot.

Xu Ping took the lenses and carefully divided them into several piles.

There are three types of reading lenses, which correspond to different distances from reading, writing, painting, and meeting guests, with slightly different focal lengths for the spherical surface. After all, the default customer is a dignitary, and the more refined the better.

Picking up the pre-made copper frames, Xu Ping used three kinds of lenses to fit three pairs of glasses, wanting to give it a try, but he knew that he felt dizzy just by taking a glance. As soon as he turned his head, he saw Yan Su, who was holding a telescope and looking at the sky outside, and said loudly: "Yan waits, you have to wait until it gets completely dark at night to see the starry sky." Come in, there's another thing here, you come in and give it a try, it's a different benefit! ”

Yan Su reluctantly put away the binoculars, held them tightly in his hands, and walked back to the living room.

Xu Ping handed over a pair of reading glasses and said, "Wear this mirror and try to see what is different about things." ”

Yan Su took it in his hand and looked at it over and over again, but he didn't know what to do, and looked up at Xu Ping.

Xu Ping stepped forward with a smile, helped Yan Su put on his reading glasses, and motioned for him to look around.

"Ah, Xu Zhizhi, why are you so young? I always thought you had a handful of black beards, why haven't they grown yet? Ahh ”

Could it be that in the eyes of these old ministers, he has always been similar to Fan Zhongyan? Fan Zhongyan has a black beard, he is only thirty years old, how can he have a beard!

Xu Ping shook his head again and again, crying and laughing in his heart, could it be that in the eyes of these bearded ministers, the subordinate officials only have a vague image, and they don't know the specific appearance? It's no wonder that in the legendary novels I saw in my previous life, the big characters were fooled by people casually changing their clothes at every turn.

Yan Su took reading glasses and looked left and right for a while, and was amazed in his mouth, and he was the most reluctant to take them off, and kept saying: "This is a good thing, a good thing!" Wearing it makes you young all of a sudden! ”

"How does it compare to a telescope?"

Hearing Xu Ping's question, Yan Su clenched the telescope in his hand tightly: "Naturally, it is more important to look at the sky, people are old and dizzy, since ancient times, in fact, there is nothing!" ”

Xu Ping smiled, ignored Yan Su anymore, and said to Qiu Zhizhao: "Waiting for the Zhao, please let your subordinates be high-footed, according to the appearance of these three pairs, put up all the others, I will use them tomorrow." ”

Qiu waited for the promise and took the apprentice to install glasses on the table.

Yan Su watched from the side, and couldn't help but ask Xu Ping: "Why, Deputy Envoy Xu doesn't send a pair of old decay?" ”

"Naturally, it will be sent, Yan is busy in the glass business, what is the glasses! Moreover, with this glasses, Yan will be able to see things clearly, and I will trouble you in a few days. ”

"Glasses? It's a good name, a mirror with an eye, a clear eye. Yan Su nodded, "In fact, all these things are done by Deputy Envoy Xu, what can the old man help?" What's going on in a few days? ”

"Although the lotus drain made by Yan is excellent, it is quite inconvenient to use. I thought of a way to make a more lightweight and practical bell leak, and then I had to wait for a helper. ”

Lotus leak is the most proud masterpiece of Yan Su's life, before he was recognized by Si Tianjian, he was an official outside, and almost every place had to build a simple version and put it in the official offices of various places. This year, it officially became the national timekeeping instrument in front of the Wende Palace, which fulfilled his wish for many years, which is what he is most proud of. Xu Ping said that he wanted to build more advanced timing instruments, which not only made him feel a little uncomfortable, but also couldn't suppress the strong curiosity in his heart.

After a while, Yan Su said: "If Xu Beizhi really has any good ideas, the old man will naturally be obligated at that time!" ”

"Then it's settled!" Xu Ping took advantage of the situation to quickly finalize.

Making timekeeping instruments such as clocks and watches is not only a matter of physics and mechanics, but also related to astronomy. Because there is no unified timing system at this time, you can't take your own clock and standard time to see if the time is accurate, and you have to measure the time yourself. Even with the relevant knowledge, without the necessary tools and experience, it is difficult to accurately measure time, let alone calibrate it to the point of tick or even the moment below.

To know the accuracy of the table, you have to know the exact length of the day and the night, and then divide it. Whether it is minutes and seconds, hours and moments, you must first set the time of the twelve hours. This is another function of the Si Tianjian, which is to accurately determine the length of a day and a night, the length of a year, and calculate the 24 solar terms from this.

Xu Ping can make a pendulum clock, but the timing and scale have to rely on the power of Si Tianjian, of course, Yan Su, who has spent half his life on the lotus drain, is a more suitable candidate. The error of the lotus leakage for one day and one night can be controlled to less than one minute, which of course requires a lot of ingenuity in the structure, but it is also essential to accurately determine the time of day.

When the busy farming season passes, Xu Ping's free time will increase, and when he has time, he will have to do something that he remembers from his past life, making money is one thing, and it is also convenient to live by himself.

It is very troublesome to not have a convenient timekeeping tool, for example, China has long been able to accurately measure the solar year, but the calendar has always been based on the solar calendar, mixed with the solar calendar lunisolar calendar. Of course, there are many reasons for this, but one important reason is the convenience of observation time. During the day, you can look at the sun to estimate the time, the sun is always the same, and at night, when you look at the moon, the moon has a change in phases. Based on the lunar calendar, people who have experienced hardships only need to know the date and look at the moon in the sky at night to roughly estimate the time, but the solar calendar does not have this function. When portable timekeeping tools such as pocket watches and watches became popular, the lunisolar calendar lost a large part of its value, and the ancient lunar calendar soon withdrew from life.

Like mirrors, clocks and watches are also everyday items that ordinary people need, with a broad market and bright prospects, which can accumulate a lot of wealth for the three divisions. These things, which require a large number of skilled craftsmen, are difficult to do privately, but it is much easier for the third division, especially when there is a helper from the Hanlin Academy.

The new field work in front is daily necessities, and after the production is stabilized, Xu Ping will gradually march towards luxury goods.

Seeing that it was getting dark, Xu Ping instructed Qiu Zhizhao and the apprentice to do what to do next, so he took all his reading glasses and left the glass with Yan Su.

Yan Su held the binoculars tightly all the way, and the reading glasses given to him didn't care much, and they were casually stuffed in his arms. And he kept urging Xu Ping, eager to have a pair of wings on his back, to find his old friend who was the heavenly supervisor, and to take advantage of the sunny and cloudless weather tonight to take a look at the vast starry sky together.

Over the years, generations of celestial observers have recorded countless star charts and attached many myths and stories to them. Today, with the help of a telescope, he was able to unveil the starry sky that he had been unable to see clearly, and Yan Su was excited when he thought about it. (To be continued.) )