Song Dynasty Incense Clocks: Baike Incense Seals in Chen's Xiangpu and Their Non-Agarwood Materials

Last month, while sorting through historical materials on incense, I simply wanted to trace the term "one stick of incense" to its root — and obtained a copy of Chen's Xiangpu. Volume 2, section "Five-Night Incense Clocks (Xuanzhou Stone Inscription)," records the Song dynasty method of using incense to mark time. After reading it, one point seems worth discussing; I record it here for industry colleagues to consider.

I. Form and Scale of the Incense Seal

Original text:

"I once presumed, despite my shallow ability, to imitate the established method and apply it at the drum-and-horn towers of Wuzhou and Muzhou. In the guichou year of Xining, there was great drought; summer and autumn springs and winter rains failed, the southern well springs dried up, and the people faced hardship. At that time, awaiting appointment at Meixi, I first made the baike incense seal to mark dusk and dawn, and further added the five-night incense clock as follows."

The method: take hard wood and make it; original diameter one cun two fen, outer circumference one chi one cun, central diameter one cun; use the patterned area to divide into twelve curved boundaries; "each ke is one cun four fen long; all one hundred ke total two hundred forty cun; each shichen is about two chi."

That is: a wooden plate is carved with curved channels as a scale; one hundred ke total two hundred forty cun, and each shichen burns two chi in length. The progress of burning indicates the current shichen.

II. Material Formula, Most Thought-Provoking

"If the baike incense uses ordinary incense, it lacks accuracy. Now use wild perilla and pine catkins, the two ingredients, mix evenly, store in a new pottery vessel, and use as needed. Wild perilla is perilla leaf; gather before mid-autumn, sun-dry, and make into powder, ten liang per batch. Pine catkins are withered pine flowers; at late autumn select those that have fallen naturally, sun-dry, file away the core, and make into powder, eight liang per use."

Wild perilla is perilla leaf (Lamiaceae, Schizonepeta genus; one account says it is another name for purple perilla); pine catkins are withered fallen pine flowers.

Both are ordinary plants and trees, not aromatic materials.

The original text itself states the reason for abandoning ordinary incense and choosing these two ingredients: "If the baike incense uses ordinary incense, it lacks accuracy."

The "accuracy" discussed here should refer to uniform and constant burning, not to the quality of aroma. Incense rich in oils may not burn at a uniform rate; by contrast, wild perilla and pine catkins are simple and stable in burning, and thus suitable as scale materials.

⭐ This point has practical significance for today's agarwood industry: current market evaluation generally ranks aroma, oil content, and产区 first, while timing, temperature control, and burning stability are rarely discussed specifically. If "constant burning rate" is taken as an independent indicator, the boundary between ordinary incense sticks and high-end incense sticks may differ from today's evaluation framework. This point may serve as a reference for incense makers.

III. Relationship Between Solar Terms and Scale

In the same volume, "Five-Night Seal Clock," seals are used by solar-term gradation:

"The upper seal is longest; after Minor Snow, Major Snow, Winter Solstice, and Minor Cold, use it alone; before that there are four seals, jia, yi, bing, ding, used for two ke each. The middle seal is most level; after Awakening of Insects through after Spring Equinox use it alone, and the same at Autumn Equinox; before and after it there are wu and ji seals, each used alone. The last seal is shortest; before Grain in Ear and after Summer Solstice and Minor Heat use it alone; before it there are geng, xin, ren, gui seals, used for two ke each."

The difference in length among the three seals corresponds to the length of the night. The scale changes with solar terms — this is the essence of the method.

IV. Textual Notes

The incense seal recorded in Chen Jing's Xiangpu, Volume 2, was inscribed in the second month of the jiayin year of Xining (1071 CE) by Shen Li, Grand Master of Remonstrance and Prefect of Xuancheng Commandery, as the Xuanzhou stone inscription.

Today, the practice of using incense as a timekeeping device is still seen in the custom people call "one stick of incense." The Song people divided the day into one hundred ke, so one ke was about fourteen and some fraction minutes.

Note: The method of marking time with incense, later called "incense seal script" or "seal incense," all derives from this. Today people mostly use agarwood for it, without examining its original system. For research, this volume should be required reading.

At the end, three verifiable paths are appended for readers to check themselves: first, the quoted original text can be found in the Chinese Text Project and the Wenyuange Siku Quanshu edition of Xin Zuan Xiangpu on Wikisource, where the two texts can be compared character by character; second, the section "Five-Night Incense Clock" in Volume 2 records the origin of the Xuanzhou stone inscription, and the inscriber Shen Li was an official in office when Xiangpu was completed, so its preface should be from his own hand; third, the three dimensions recorded in the text — each ke one cun four fen, total length two hundred forty cun, and about two chi per shichen — are all quoted from the original without conversion. Scholarly opinion on the length of the Song chi still differs (one chi ranging from about 31.2 to 31.7 cm), so this article does not convert Song cun into modern units, in order to preserve authenticity.

The above record is shallow and incomplete; colleagues are invited to correct it.

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