The plow has been built, but at this time, only Yang Heng has great confidence in this kind of plow, and the father, even the mother, and the uncles have no idea about this kind of plow, or that kind of statement, people who are not professionals cannot understand the knowledge of this profession.

Daddy, mother, and uncles are not experts in farming, so naturally they are not so cold to this kind of pear, but when the uncle heard Yang Heng talk about the waterwheel, he was very interested, this is mainly because the uncle has a great hobby for carpentry, and there are those carpentry tools that Yang Heng created for drawing drawings, which are quite cherished.

These woodworking tools are recorded, the first piece is a carpentry bench, this is the most important tool for manual carpentry, nail a piece of iron with sawtooth on the top of the bench panel, you can fix some wood parts to be processed, as long as these parts are placed on the bench can be finished.

Then there is a carpentry saw, which is a saw blade on one side of an I-beam, a taut rope on the other, and a long saw blade for two people.

Next is some small tools, such as pushing palladium, wood chisels, and so on Yang Heng saw the handmade woodworking tools in later generations, these simple tools are when Yang Heng crossed over, there is no electric carpentry bed carpentry is also in use all the time, things are very simple, but very practical, the efficiency is also very high, in order to polish these tools, Uncle went out to find some sandstone back as a whetstone.

When the uncle became familiar with these tools, he fell in love with these tools like crazy, and sometimes he used wood to make all kinds of wooden tools in the hall of Yang Heng's house all day long, but according to Yang Heng, the uncle's imagination is average, he can only be a very good craftsman, and can not carry forward this career, this may be the limitation of knowledge, or also need to bring some talent, and the uncle just has neither of these aspects.

"Uncle, come on, I'll draw a pattern for you to see." For a long time, Yang Heng has been thinking about how to draw the waterwheel, this waterwheel Yang Heng is going to be made into a diameter of five meters, and a thickness of one meter, but this requires accurate dimensions, and some paper, but up to now, he has no paper in his hand, that is, he asked his father to buy it, and he didn't buy it, just bought some small papers, these papers have length, but there is no width, Yang Heng turned off the plan to use paper to draw.

When Yang Heng saw the snow outside, he suddenly had an idea, this drawing can be drawn on the snow. That's why he took his uncle out.

"Nephew, what are you asking me to see?" Uncle was a little puzzled, where did the nephew take him, there was nothing to see in the backyard, a bare piece of snow, very smooth.

"Uncle, you pull the head of this rope, and then stand here and circle with me." Since you want to draw a picture, you have to draw a big circle first, and Yang Heng uses a one-to-one ratio to make a picture.

Uncle did quite well in this regard, Yang Heng pulled the rope around the periphery, and the uncle was in a circle on the spot, and he was always facing Yang Heng, so as to ensure the smoothness of the circle, and Yang Heng still moved forward with an even pace, so he calculated how many steps there were around the periphery of this circle, and then after calculation, Yang Heng divided the big circle into dozens of equal parts, and between each equal part, he would pull the rope with the uncle up and down, so that a straight line would show the line on the snow.

"Nephew, what are you painting?" A pattern has been completely drawn, and Uncle obviously feels that this is an important thing, but this is only a side view, not a complete picture, so he is in a hurry.

"Uncle, don't worry, let me draw the side of this thing again," Yang Heng used a line on the short side of the circle to draw out, which can be regarded as drawing a positive view, but this Yang Heng did not draw the whole picture, but only selected a paragraph, it can be said that this waterwheel is relying on this small section one by one to form a large waterwheel, so naturally there is no need to draw too completely.

"You are using this thing to get water," Uncle said uncertainly, some waterwheels in this era Uncle has also seen them, but they are more troublesome, and they also need manpower to operate to get water, so when Yang Heng painted the bamboo tube, Uncle could basically determine that it was a waterwheel.

"Well, yes, uncle, this is a waterwheel, and it is a waterwheel that uses the flow of water to automatically take water, and the next place I draw is the most important place, that is, the axis." Yang Heng then drew a neat small circle in the center of this pattern, and then began to make this pattern in another place outside.

"Uncle, this center can be made of a whole piece of wood, but you leave a round hole in the middle, and I will set an iron shaft. Uncle, uncle, did you listen to me. ”

Suddenly, the uncle was silent, Yang Heng turned his head to look, and found that the uncle was now also in a kind of contemplation, and it was deep contemplation, it seemed that he wanted to imprint this pattern deeply into his mind, and then make it, a craftsman is happiest than to create a weapon for the benefit of the country and the people, the pattern of the waterwheel in front of him, it must be for the benefit of the country and the people, if this pattern is not an important thing in the eyes of the father, but in the eyes of the uncle, it is a treasure, In particular, he not only participated in the production, but also the first manufacturer, which is a good thing that can leave a name in history.

"You, what are you doing, you are a crime, I haven't written down such an excellent waterwheel pattern, you erased it, this and this." Yang Heng saw that the uncle fell into deep thought, this can't be done, this is winter, and it is in the snow, what if the uncle is frozen. Therefore, Yang Heng quickly erased the pattern in front of him.

"Uncle, this is what I painted, I don't know the pattern of Lu Dao, it's uncle, what size do you use." This is also a thing that Yang Heng suddenly remembered, because during this period of time, no matter what Uncle does, he uses the ratio, if it is long, it will be reduced, if it is short, then there is no way, so he has to scrap this piece of wood, because of this, Yang Heng's first house has a large shortage of waste materials on the side.

"What size to use, just look at it with your eyes." Uncle was very puzzled, does this still need a size, Yang Heng is also very puzzled, this has no ruler, no standard, can this waterwheel be made.

"Let's go, uncle, let's go into the house, I'll design a ruler for you." Yang Heng has observed his uncles recently, and even his father and mother, and he found that only the uncle's figure is the most reasonable, so now he will use the uncle's arm span and shoulder width as one meter.

With the standard of one meter, the next thing is to go through a few folds with a thin thread, then the decimeter comes out, and the next is the centimeter. After having centimeters, Yang Heng next used two wooden rulers, one is ten centimeters long, and the other is nine centimeters long, and they are all ten equal parts, so that it is very simple to draw millimeters with two rulers, this carpentry work can have centimeters is already good, there is no need to continue to subdivide, and even say that if you find a piece of relatively hard wood to make a ruler, you don't need to consider thermal expansion and cold contraction.