The ancients were clever in their way, and a "time-fixing incense" was invented. The Hong Chaohe almanac explains its use in determining time of birth: "Light the incense immediately upon the birth of the child.
古人自有智慧，發明瞭一種「定時刻香」，洪潮和通書中這麼解釋它的用途：「… … 俟產下之後，隨即起點（香）。