After coming to Datang, Li Yuanjia understood a truth.

That is, if you want to make something ahead of the times, you have to pay a price, and the price depends on how much that thing is ahead of the times.

The less the lead era, the less price to pay.

For example, the thirteen incense that once made Han Wangfu make a lot of money, in essence, does not require particularly high technology, as long as you know the recipe, and then crush those spices and mix them together. Therefore, Li Yuanjia was able to take advantage of the fact that the stir-fry had just become popular in Chang'an City, and made a lot of money with thirteen spices.

The key to this is a time lag.

Because this thing really doesn't have any technical content, others can always make it out with a little bit of trying, at most it's just a slight difference in taste.

But things such as curved plows, overturned cars, and iron pots are slightly more expensive.

The curved plough and the overturning car are slightly more complex in structure, so they need to consume more labor, and the price is naturally high. As for the iron pot, it is not only necessary to consume more labor to manufacture, but also has technical requirements.

It can be seen everywhere in modern society, and if it is cheap, you can buy an iron pot for more than a dozen yuan, and Li Yuanjia didn't expect it to be so troublesome to build during the Zhenguan period. Because the iron pot must be made round enough and thin enough to be evenly heated and cooked quickly when stir-frying, the casting technology of this era ......

To put it simply, it's hard to put it into words.

Otherwise, the blacksmiths of the palace would not have spent so much thought and time to make an iron pot that satisfied him. In addition, the price of iron is already high in these years, so the price of an iron pot has always started, if you take it to buy rice, how much can you buy?

Only when the process matures slowly, the price will come down.

But in a short period of time, ordinary people don't want to use it...... Of course, depending on the price of iron in these years, they can't afford to use iron pots, and it's good to have a clay pot at home.

If you have that spare money, you might as well spend it on farm tools.

The only thing that can make Li Yuanjia feel cheap may be the good paper made by the Hanwangfu paper workshop. Compared with the top white paper of the same era, because Wang Pu and Niu Da Niu Er have improved their technology, they may be lower if they only consider the manufacturing cost.

However, if you take into account the investment in R&D before, the price will at least double.

And this is just traditional paper, if it is bamboo paper that Li Yuanjia values more, then the price paid will be even higher.

During the Ming and Qing dynasties, bamboo paper was mainly used because of its low price, but there was no "advanced" crushing method in Datang, and it could only rely on manpower to crush bamboo, and the use of coal was not widespread enough, and the boiling temperature could not go up, so the cost of making paper from bamboo would be relatively high......

These things are not too many types that are ahead of their time.

If it's a lot of things that are ahead of their time, such as metal movable type printing, and then transparent glass...... Let's not talk about how these things are used, but the cost is definitely not cheap anyway. Especially movable type printing, clay movable type or wooden movable type Li Yuanjia can't look at it, and it is not as good as engraving to use, and metal movable type is really expensive and makes people tremble!

The four-wheeled carriage, in fact, is the same reason.

Don't look at it, they are all made of wood, but the volume of the four-wheeled carriage is larger, which consumes labor and wood, and naturally has more wood; And more importantly, the structure is relatively more complex, and the requirements for carpenters are higher!

All these factors add up, and the result is that the cost of building a four-wheeled carriage is now several times higher than that of a two-wheeled one!

Li Yuanjia said ten times, which is not too exaggerated.

After going around his carriage a few times just now, the emperor naturally understood what Li Yuanjia meant, and he also knew that it would be a lot more expensive to build such a carriage.

However, he still frowned and asked: "Eleven, it doesn't matter if the carriage is more expensive, as long as it can carry more goods, but what do you mean by saying that there are too many restrictions on use?" ”

The Tang Emperor has craftsmen under him, and there is too much wood in the world to be used up, as long as he can transfer more grain from Luoyang to Chang'an, it is not a matter in the emperor's opinion!

"Road! The key is the road! ”

Taking a deep breath, Li Yuanjia spread his hands helplessly and said: "Look at this carriage, it is tall and big, wide and heavy, the road in Chang'an City is naturally no problem to run, but if you want to run outside the city...... Second brother, I'll tell you the truth, I've been sitting all morning, but I've suffered a lot of sins! ”

Even in Europe, the real popularity of horse-drawn carriages was not until after the fifteenth century.

The place where horse-drawn carriages were actually used before that was in ancient Rome was because they had the largest road system in the world that could support four-wheeled carriages - 80,000 kilometers of 400,000 kilometers of roads were made of stone.

So after a general explanation, Li Yuanjia smiled bitterly: "After pulling it out and trying it once, I finally confirmed that only the road surface made of stone slabs and other things can support the weight of this carriage, and the roads made of mud in our Datang Dynasty...... It's hard! ”

"This ......"

After being stunned for a moment, Li Shimin quickly figured out the truth.

After all, he was born as an emperor, and unlike those ordinary emperors who grew up in the palace since childhood, Li Shimin understood it as soon as he heard it. It's like the team that transports the baggage in a war, and the heavier the car, the more difficult it is to walk, especially on the muddy roads after the rain......

Seeing that the emperor's face was not very good-looking, Li Yuanjia also felt a lot of pain in his heart.

It's been a few years!

Although Chen Mu and the others didn't just do this one thing, Li Yuanjia was always thinking about the four-wheeled carriage, a big killer, and he kept reminding them.

It took several years to finally build one.

For this four-wheeled carriage that can run on the road, Li Yuanjia really racked his brains - expecting Chen Mu's wooden heads to improve the carriage's device is simply a fantasy!

Relying on the memory and physical knowledge in his head, Li Yuanjia designed the steering device of the carriage little by little, improved the shock absorption system, and specially built a brake device. Although the final product is very simple, it is a complete carriage after all!

But when I came out this time, I found that the problem was not in the carriage at all.

The road is not good, the four-wheeled carriage is a waste!

Fortunately, the official road from Chang'an to Shiping is in good condition, and it has not rained recently, so there were a few bumps in the morning after running down, and Li Yuanjia was quite comfortable in the carriage most of the time. But considering that this is the territory of Yongzhou, where the capital of the Tang Dynasty is located, he has little confidence in the road conditions in other places.

At least he had seen the situation in Luzhou, and the possibility of running this four-wheeled carriage was very small.

If you want to use it, you have to build roads......