Chapter 22 Waterwheel

  The plow has been made, but at this time, only Yang Heng has great confidence in this plow. His father, mother, and uncles all have no idea about this plow, still speaking the usual way, non-professionals can't understand professional knowledge.

  The old father and mother, as well as the uncles, were not skilled in farming, so they didn't care much about this pear. However, when Yang Heng mentioned the waterwheel, his younger uncle was very interested. This was mainly because his younger uncle loved woodworking, and also because of the wooden tools that Yang Heng had drawn out on paper and crafted with great care.

  These woodworking tools are recorded, the first one is a long bench for woodworking, which is the most important tool for manual woodworking. On the surface of the long bench, a piece of iron plate with saw teeth is nailed at one end, and some wood parts to be processed can be fixed on it. As long as these parts are placed on the workbench, they can be finely processed.

  Then there is a woodworking saw, which is installed with a saw blade on one side of the workbench and a tight rope on the other side, as well as a long saw blade for two people to use.

  Next are some small tools, such as chisels, hand planes, etc. The manual woodworking tools that Yang Heng saw in later generations were still being used when he crossed over, without electric woodworking beds. These simple tools are very practical and efficient. In order to sharpen these tools, Xiao Shu specially went out to find some sandstone to use as a whetstone.

  When the young uncle became familiar with these tools, he crazily liked them and sometimes spent all day in Yang Heng's hall making various wooden objects. However, according to Yang Heng, his imagination was ordinary, and he could only be a good craftsman but not develop this business further. This might be due to the limitations of knowledge or perhaps also require some innate talent, which the young uncle lacked both.

  "Little uncle, come here and I'll draw a pattern for you to see." Yang Heng had been thinking about how to draw that waterwheel all along. He planned to make it five meters in diameter and one meter thick, but this required precise dimensions and some paper. However, up until now, he didn't have any paper on hand. Even when he asked his old father to buy some, he hadn't brought any back, only purchasing a few small sheets of paper that had length but no width. Yang Heng gave up the idea of using paper to draw the picture.

  When Yang Heng saw the snowy ground outside, he suddenly had an idea that this drawing could be drawn on the snowy ground. That's how he ended up pulling his little uncle out.

  "Nephew, what are you showing me?" The young uncle was somewhat perplexed. Where was the nephew taking him? The backyard didn't have anything good to look at, just a vast expanse of empty snowy ground, very flat.

  "Uncle, you hold this rope head and stand here on the spot while I turn around." Since he wanted to draw a diagram, he had to start by drawing a large circle first. Yang Heng adopted a one-to-one ratio for his drawing.

  In this regard, the younger uncle did a good job. Yang Heng was pulling the rope in circles on the outside, while the younger uncle was turning in place and always facing Yang Heng, ensuring the smoothness of the circle. Yang Heng also moved forward at an even pace, calculating how many steps it would take to complete the outer circle. After calculation, Yang Heng divided the large circle into dozens of equal parts, and between each part, he and the younger uncle would pull the rope up and down in a straight line, leaving a trail on the snowy ground.

  "Nephew, what is this that you've drawn." A pattern had already been completely drawn, and Fourth Uncle could clearly sense that this was something important, but it was only a side view and didn't show the full picture, so he felt anxious.

  "Uncle, don't be in a hurry, let me draw out the side view of this thing," Yang Heng drew a line on one of the short sides of the circle, which was equivalent to drawing an orthographic projection. However, Yang Heng didn't draw it completely, but only chose a segment. It can be said that this waterwheel is composed of many small segments like this, so there's no need to draw it too thoroughly.

  "This is something used to fetch water," said the young uncle uncertainly. In this era, he had also seen some waterwheels, but they were all quite troublesome and required human labor to operate in order to fetch water. So when Yang Heng drew a picture of a bamboo tube, the young uncle was basically certain that it was a waterwheel.

  "Ah, yes, little uncle, this is a waterwheel, and it's an automatic waterwheel that uses the flow of water to fetch water. The next place I'm going to draw is the most important part, which is the axle." Yang Heng continued to draw a neat small circle in the center of the pattern, and then started making the pattern again from another place outside.

  "Little uncle, this hub can be made from a single piece of wood, but in the middle you need to leave out a round hole for me to insert an iron axle. Little uncle, little uncle, did you hear what I said?"

  Suddenly, the young uncle lost his voice, and Yang Heng turned to look at him, only to find that he was also deep in thought. It seemed that he wanted to imprint this pattern deeply into his mind and then create it. A craftsman's greatest joy is to personally craft a tool that benefits the country and its people. The pattern of the waterwheel in front of him must be one such thing. This pattern might not be important in the eyes of his father, but to a professional like his uncle, it was a treasure. Especially since he not only participated in its creation but was also the first person to manufacture it - this was an opportunity to leave a mark on history.

  "What are you doing? This is a crime! Such an excellent waterwheel pattern, I haven't even memorized it yet, and you've erased it!" Yang Heng saw his little uncle fall into deep thought. This won't do, it's winter, and we're in the snow. If Little Uncle gets frozen stiff, what then? So Yang Heng quickly erased the pattern in front of him."

  "Little uncle, this is what I drew, and I don't know what size you used." This was also something Yang Heng suddenly remembered, because during this time, little uncle would always use a larger size, if it was too long he would cut some off, but if it was too short there was no way to fix it, so the wood would be wasted. That's why the first house in Yang Heng's family had a big pile of leftover scraps on the side.

  "What size to use, just estimate with your eyes." Xiao Shu was puzzled, did they still need a size for this? Yang Heng was also puzzled, without a ruler or standard, how could they possibly make this waterwheel?

  "Come on, little uncle, let's go inside and I'll design a ruler for you." Yang Heng had been observing his uncles, even his parents when they came to visit, and found that only Little Uncle's body proportions were the most reasonable. So now he would use Little Uncle's arm span and shoulder width as one meter.

  With a meter as the standard, next use a thin line to fold several times, and then the decimeter comes out. After that, it's centimeters. With centimeters, Yang Heng used two wooden rulers, one was 10 cm long and the other was 9 cm long, both were divided into ten equal parts. In this way, using two rulers can easily draw millimeters. The woodworking work is already fine with centimeters, so there is no need to continue subdividing. Even if you find a harder piece of wood to make a ruler, you don't have to consider thermal expansion and contraction.