In his previous life, the Ministry of Agriculture promoted the fuel-saving stove nationwide, hoping that all farmers could master this technology themselves. Therefore, the relevant technical specifications were designed to be extremely simple and easy to understand. Brian Cooper only spent a few days in a rural area learning from an agricultural technician before he fully grasped it. Brian Cooper believed that if he explained these specifications to the villagers, they would quickly master them as well.

At first, Brian Cooper did intend to promote this technology, but Charles Cooper's words just now suddenly changed his mind. In that era, people with skills always kept their craft tightly guarded, sometimes even passing it only to sons and not daughters. Having the skill to modify the fuel-saving stove and not teaching it to unrelated people was something everyone could understand.

A person must have some unique ability to survive and establish themselves in the world. The current Brian Cooper only knew how to read a few books and was physically weak; what he could rely on to survive was still a mystery. In this situation, having accidentally discovered that he possessed a skill others valued, it was only natural to find a way to maximize its benefit.

The principle behind the fuel-saving stove is actually quite simple once explained, but without someone to clarify it, others would find it hard to see the ingenuity. Concepts like thermal efficiency, heat radiation, complete combustion, and fluid dynamics were completely unknown in the Ming Dynasty, let alone in its rural areas. Without these theoretical tools, just relying on the naked eye meant outsiders could only watch the excitement without understanding the real essence.

In fact, the women who had just visited Brian Cooper's house to see the fuel-saving stove had also pondered over it, but simply couldn't tell what was different about Brian Cooper's stove compared to their own. That was exactly why they needed to ask Brian Cooper for help with the modifications.

With Charles Cooper helping out, Brian Cooper's workload was indeed much lighter. Tasks like collecting soil and mixing mud were all handed over to Charles Cooper. True to his word, Charles Cooper did whatever Brian Cooper asked and, besides that, made sure not to look at anything he shouldn't, so as not to give the impression that he wanted to steal Brian Cooper's craft.

Brian Cooper took the pot off the stove at Charles Cooper's house, used a chisel to remove some of the original clay from the hearth, and adjusted the position of the smoke vent. This was a key technical step in making the fuel-saving stove: it was essential to ensure that fresh air entering from the stove mouth could circulate fully inside the hearth, guaranteeing enough oxygen for the fuel. Others, if they dismantled this modified stove, could see the changes inside, but would have a hard time understanding their purpose. So, without someone to explain, even if others copied the design, their stoves would be much less efficient.

After finishing the hearth, the next steps were to thicken the stove wall and reduce the size of the stove mouth—tasks that Charles Cooper could handle. The final step was to raise the chimney; Brian Cooper gave a measurement, and Charles Cooper climbed onto the roof to do it.

Once all the work was done, Brian Cooper asked Charles Cooper's daughter to bring some rice straw to burn in the hearth, so the clay would dry quickly, while he sat in the main room of Charles Cooper's house to wait.

As Brian Cooper was nearly finished, Jinwang's wife had already hurried to a neighbor's house to borrow a fire and cook two bowls of rock sugar eggs, which she now brought over—one for Brian Cooper, one for Emily Scott.

"Auntie, we're all neighbors, why bother making soup?" Emily Scott looked at the rock sugar eggs, beaming with joy, but still pretended to scold her. In the countryside, rock sugar eggs were called "soup" and were a way to treat honored guests.

In those days, every household's grain was scarce, and they could usually only keep one or two chickens, so eggs were a rare treat. Even though Brian Cooper was pampered at home, it wasn't easy for him to eat an egg. That morning, he had used two eggs to make a custard for the whole family, which had made Emily Scott feel a bit distressed.

Jinwang's wife said, "Hao boy is a scholar, and he's worked so hard for our family—I feel embarrassed. His uncle can't help much, so of course I have to make a bowl of soup."

Emily Scott actually wanted her son to have this bowl of eggs, so upon hearing this, she went along and said, "Hao boy has worked up a sweat, so it's right to make him a bowl of soup. I didn't do any work, so let the children have this bowl instead."

As Emily Scott declined, Jinwang's wife insisted several times. In the end, Brian Cooper ate two of the three eggs in his bowl and left one. This was customary: leaving one meant you were too full to eat more, showing that the host had been generous. If you ate all three, wouldn't that mean the host wasn't hospitable enough and hadn't made enough food?

After some polite back-and-forth, Emily Scott finally took a bowl, picked out one egg from her own bowl and ate it, leaving two. Jinwang's wife called out, and the children in the house came running, happily dividing up the three eggs left by Brian Cooper and his mother.