Yang Cong was stimulated by the Ming Dynasty version of the car or walk-behind tractor invented by several peasant children, and finally realized that he himself was the biggest "inventor" of this era.

So, what is it good to invent?

First of all, this thing definitely has to be useful, and the more useful it is, the better.

The list of things he can "invent" is simply too numerous, so to speak, even he himself can't count, if it's useless, then what's the point of inventing it, entertaining himself, he's not so idle.

For example, children's toys, if he wants, let alone several, dozens or even hundreds of kinds can be "invented".

However, how meaningful is it to invent it, at least, it has no meaning for the current Ming Dynasty.

His time is precious, and he can't afford to waste it on these meaningless things.

Then, this thing must be simple, and the simpler the better, if it is too complicated, it will take years or even more than ten years, and it will be even more meaningless.

He is not like Jiajing, fantasizing that he can live forever, people have only a few decades in this life, and time is very limited, how to use this time, "inventing and creating" more practical things is serious.

For example, the common computer and mobile phone in later generations, is that thing good?

There is no need to ask this question, it is definitely too good to work, and the key thing is too complicated, even Yang Cong doesn't understand it very well.

If you want to invent it, the process is unimaginably long.

There was not even electricity at this time, from the invention of electricity, to the invention of generators, to the invention of electronic components, to the invention of various chips, to the invention of software ......

This process is so long that it is desperately long, and there is no need to think about it for tens or hundreds of years.

Yang Cong naturally doesn't think about these unattainable things, what he wants to do now is the kind of simple and practical things.

At first, he also thought about using the steam engine to make a fuss and invent some useful machinery.

However, after thinking about it for a long time, he reluctantly found that he seemed to know, simple and practical machinery, he had almost invented it, and other machinery, he did not have those craftsmen who understood it, and it was easier for others to ponder than for him to ponder.

There is nothing to think about this steam machine, so what is there such a simple and practical thing?

He racked his brains and thought about it for a long time, and finally thought of a thing, this thing was not widely used in later generations, but at this time, it was quite practical, and the use was so big that it was unimaginable.

This thing is a telescope!

Telescopes have been one of the essential equipment of battlefield commanders for a long time, but it seems that they have been gradually phased out after the appearance of satellites.

The telescope, before the advent of satellites, was a necessary artifact on the battlefield

Of course, this artifact is based on the premise that you have enemies that you don't have.

If everyone has it, it's not an artifact, it's a regular piece of equipment.

At this time, there is no telescope in the world, if you can make it, it is definitely an artifact on the battlefield, the so-called knowing oneself and knowing the other is invincible, when the enemy is not clear about your reality, you have already seen the enemy clearly, this battle is fought, it is difficult to lose.

Now that the glass is there, can't the telescope be made?

To put it bluntly, the telescope is to overlap the two concave and convex mirrors together, as for how to stack, with a concave mirror or a convex mirror stack, these are not a problem, anyway, try to know, the most important thing is that the surface of the concave and convex mirror must be smooth, if it is rough and rough, it is not clear at all, then it is useless.

Can you make the concave and convex mirror smoother than a mirror in these years?

This problem doesn't seem to be a problem, because there are many gold, silver, and jade objects at this time, and the surface is quite smooth, and even the bronze mirror, which is smooth enough to reflect the human figure.

In other words, the craftsmen of this era have their own unique methods to make the surface of the processed things smooth as mirrors, which is not doubtful, but I just don't know if this kind of person is good to find.

As soon as Yang Cong remembered the role of the telescope on the battlefield, the momentum came up, and he immediately ordered someone to invite Wang Xuan, and when the two met, they exchanged a few polite words, and he couldn't wait to ask: "Sir, are there any craftsmen who process gold, silver, jade, or bronze mirrors among your students?" ”

When Wang Xuan heard this, he couldn't help but be curious: "What, do you want to make jewelry, this is simple, send the materials directly to the capital, what jewelry can't be processed?" ”

Yang Cong hurriedly explained: "No, no, sir, I want to process something, the surface of this thing must be very smooth, without any flaws, just like the surface of gold, silver and jade or copper mirror." ”

It turned out to be this meaning, Wang Xuan nodded hurriedly and said: "Although there are not many craftsmen who process gold, silver, jade and bronze mirrors, most of them are concentrated around the capital, and there are still so many craftsmen among my disciples, what do you want to process?" ”

Yang Cong thought for a while, then shook his head and said: "I can't say this for a while, it's okay to have such a person, you order someone to inform them to go to the smelting academy, let's go, we will go too, and we will meet there." ”

What does this kid want to do?

Although Wang Xuan was a little curious, he didn't ask in detail, because Yang Cong often made some inexplicable moves, even if you asked, you couldn't ask clearly, and as soon as it was done, you suddenly realized, he was used to this, so he simply didn't ask.

The two soon came to the metallurgical school, and several of Wang Xuan's disciples were already waiting there at this time.

Yang Cong didn't say much, when he even took them to the glass-firing workshop and ordered someone to take the pen, ink, paper and inkstone, he compared them on the spot.

He didn't say anything about the telescope, he just roughly drew the appearance of the concave and convex mirror, and set the size, let people open the mold, and do it immediately.

At this time, the glass processing is not the same as the later generations, the glass processed by the later generations is the boss piece by piece, if you want to make door and window glass, you have to use a glass knife to scratch piece by piece, and there is no glass knife at this time, Yang Cong is too lazy to let people find any diamond to make glass knives, but directly let people make abrasives, all kinds of door and window glass sizes are set to death, and they can be installed directly when they are made, and there is no need to scratch at all.

Therefore, at this time, there are materials for making abrasives in the workshop for firing glass, and the size he requires is quite small, that is, the diameter of one inch and two inches, and the concave mirror and convex mirror are the same, a total of four molds, which is naturally not difficult to make.

This mold was made quickly, the glass water was also ready-made, and the lens of the concave-convex mirror was naturally processed quickly.

However, the surface of the abrasive is not so smooth, and the lenses made cannot be used as lenses for telescopes.

Yang Cong took the hairy concave and convex lenses and said to the disciples: "This is what I want you to process, you want to find a way to polish both sides of it, and it should be as smooth as a copper mirror, without any flaws." ”

They naturally knew this work, and as soon as Yang Cong said it, they nodded and took the lenses and went to work.

Immediately afterwards, Yang Cong asked Wang Xuan to find a few craftsmen and disciples to build several monoculars with copper, that is, one large and one small, the two ends are tightly combined, and they can slide back and forth.

These things are not very difficult to process, and the next morning, Wang Xuan came over with his disciples with the processed lenses and tubes.

Yang Cong took the processed lens and roughly tested it, it turned out that the small end should use a concave lens, and the large end should use a convex lens, and the two lenses should be combined together, and then slowly adjust the focal length, you can see things in the distance.

This guy, Wang Xuan watched Yang Cong tinkering there with lenses and lens barrels at first, and he didn't know what Yang Cong was going to do, when Yang Cong stuffed the adjusted telescope into his hand and explained a few words, he was stunned.

This thing can see the scene in the distance clearly, and it is quite clear, as if it is close in front of you!