Improved Abacus
After Li Shimin, along with a visibly embarrassed Fang Xuanling and the others, took their leave, Li Zhi followed Pei Feishu to the Imperial Treasury Workshop.
There were still many refractory and precise components needed for the steel furnace, all of which required the skilled hands of the craftsmen at the workshop. Li Zhi had no time to engage in political rivalries with the court ministers at present.
As the days passed, the various construction projects neared completion. The swimming pool was the first to be finished. It resembled a modern public bathhouse—simply a grand palace with a large pit excavated at its heart. The main structure was built with brick and mortar, which retained heat well. The walls were adorned with tile mosaics forming murals, while the pool and floor were paved with plain white tiles. The water supply and drainage pipes connected to an adjacent boiler room—though the boiler itself had yet to be installed. Within the palace, a separate room was set aside for changing clothes and resting.
The second project completed was Li Zhi’s inn. After several months of construction and decoration, it finally opened its doors to guests. On opening day, Li Zhi placed baskets of flowers on either side of the entrance. It was the height of the blooming season, so gathering fresh flowers was no trouble at all. To attract customers, Li Zhi had firecrackers made—an instant novelty that drew a large crowd the moment they were lit. The people, having never seen such a thing, were first startled, then quickly broke into lively discussion.
Pei Mingli, who had hired the innkeeper from another establishment at a generous salary, now accompanied Li Zhi on a tour of the premises. This was the first time Li Zhi had found time to visit his own inn; previously, he had relied on Yan Lide to supervise on his behalf due to his busy schedule.
The inn was lavishly appointed throughout. The walls were covered with new ceramic tiles invented by Li Zhi, the floors were smooth marble, and every room was furnished with elegant Linde brand furniture. Even the restrooms were divided for men and women, with ceramic toilets provided.
Pei Mingli proved himself a shrewd businessman. Realizing the inn required a great deal of porcelain, he built his own kiln, significantly reducing construction costs while creating a new source of revenue. The inn soon welcomed its first guests, who were dazzled by the luxury. The innkeeper, Uncle Fu, greeted them warmly, personally introducing the facilities and their uses.
Pleased, Li Zhi said to Pei Mingli, “Manager Pei, from now on, you will handle all my business affairs. There is no need to report appointments to me.” Grateful for such trust, Pei Mingli replied, “I will not fail Your Highness.” Li Zhi waved him off, “A man of your talent shouldn’t be wasted—otherwise, I might find myself with a formidable rival.” Pei Mingli responded awkwardly, “Your Highness jests. I would not dare to compete with you in business.” Li Zhi laughed, “There’s no need for such modesty. When it comes to business, I may not be your equal.”
Before Pei Mingli could reply, Li Zhi continued, “Now that we have a model inn, I believe these new building materials will soon find great favor. You’ll have your hands full.” Pei Mingli assured him, “Rest easy, Your Highness. I will manage the business well.” After a few more words, Li Zhi departed, suddenly recalling that producing firecrackers might offer the court a new source of income.
Excited, he went straight to Li Shimin and shared his idea. Li Shimin frowned, “The court is currently studying gunpowder for military use. If we release it commercially now, our enemies may take notice.” Li Zhi replied, “Forgive my candor, Father. Gunpowder originated among the people, and its formula is not secret. I believe it is already too late to prevent its spread.” Li Shimin considered this, “Until now, it was never widely circulated. Even if someone stumbled upon it, the formula was never fully worked out.” His gaze grew resolute. “Let us put this matter aside for now. We can revisit it when the time is right.”
Li Zhi conceded the point. Before the precise formula for gunpowder was widely known, it was unwise for the court to hasten its spread. With this settled, Li Zhi took his leave from the Hall of Supreme Harmony.
Li Shimin nodded, offhandedly adding, “The renovation of the ironworks is nearly complete. Oversee the work on my behalf.” Li Zhi agreed. Li Shimin continued, “It is nearly June. The departments and provinces will soon begin their accounting. I must keep a close watch on these matters.”
Li Zhi was struck by this reminder. He recalled that every year at this time, all departments and provinces of Great Tang would assemble to tally the previous year’s revenues and expenditures—a laborious process that, by current methods, would not be finished before the end of September at the earliest. He was tempted to volunteer for the task, but then remembered that he had only just begun studying mathematics and could not logically possess such expertise. He quickly held his tongue and took his leave.
After leaving the Hall of Supreme Harmony, Li Zhi and Liu An visited the few acres of land he had leased at great expense. He had hired workers to plant cotton there, and it was said to be growing well. Sitting in his carriage, Li Zhi fell into deep thought, searching for a way to help Li Shimin with the accounts.
After much deliberation, he devised an excellent solution—not a novel one, but an improvement upon the existing counting boards used in Great Tang, transforming them into the abacuses of later generations. The current counting boards were simple wooden planks carved with grooves, divided into upper, middle, and lower sections. The top and bottom grooves held beads of different colors; each bead in the upper section counted as five, each in the lower as one. To use it, one had to move the beads back and forth into the central groove by hand. While the central groove’s counting method was similar to the abacus, the process was cumbersome and scarcely faster than mental arithmetic.
Li Zhi was confident that replacing the counting board with an abacus would greatly accelerate calculations. So, after a quick inspection of the cotton field and a few instructions to the tenant farmers, he hurried back to Chang’an and immediately explained the method for making abacuses to Pei Feishu.