Autumn, the twenty-third year of Zhenguan.
The morning fog in Chang'an City has not yet cleared, and there is already a tinkling sound coming from the embankment of Longshou Canal. Li Chengqian squatted by the canal and picked up a piece of iron filings glowing with blue light at his fingertips - this was ground down during the test rotation of the newly cast water wheel shaft last night. It was 30% harder than the wrought iron in the blacksmith shop in Fang City, but it had a strange toughness.
