《全真坐钵捷法》

The author states that he observed and consulted the ancient calendar in measuring time: reckoning from the winter solstice of a given year to the winter solstice of the following year, this interval is used to fix the cycle of one year. The ancients divided a day and a night into one hundred ke; as a rule, eight ke and twenty fen made one shichen (double-hour), while the shichen of yin, shen, si, and hai each had nine ke, and day and night were bounded by the zi and wu hours.

The water clocks (vessels that measure time by the flow of water) now used in different places are not alike and are not made according to the ancient method. Some craftsmen alter them at will according to their own ideas, and the instruments lack a uniform standard, so the timekeeping is prone to error, running either fast or slow. The author therefore set down this method of the circulating drip-clock, claiming that it can be used over the long term, that it requires neither much labor nor a great outlay of resources, and that it is simple to make yet precise in measuring time. Even ten thousand li away, one may carry the method along and use it at the desk.

The author holds that the regularities in the motion of the heavenly bodies can all be shown in everyday timekeeping. Some people use a sundial (telling time by the sun’s shadow) or incense coils (lighting coiled incense and reading time from the progress of its burning), but each of these methods has its limits: when the incense is dry it tends to burn quickly, and when it is damp it burns slowly; a sundial can be read on a clear day but cannot be judged when the sky is overcast. Neither, therefore, is suited to stable timekeeping over a long period. The method the author presents looks simple, yet it in fact contains a finely worked design for measuring time.

Method of Making the Basins

The method is to prepare two bronze basins, one large and one small. The original text then says again: “The large one need only be made in this way; it looks simple, yet through it one can comprehend the subtle, and within the marvel there is a further marvel.” The sense here seems repetitive, or something appears to have dropped out; the surviving passage does not further explain the exact dimensions of the two bronze basins or the method of making them.

This method of timekeeping requires two copper basins (yu, vessels for holding water): one large and one small. The large basin is used to hold the water and has no fixed size; it need only be somewhat larger and wider than the small basin. If copper basins are unavailable, porcelain basins may be used instead.

The small basin weighs five liang, stands three cun and four fen high, and measures four cun and seven fen across at both the rim and the base, with sides running straight from top to bottom. Because the dimensions may err slightly in the making, fifty Taiping coins may be taken as the standard of weight. Once the small basin is finished, a very small hole, about the size of a stitch made by a needle, is drilled in its bottom. When the small basin is floated in the large basin filled with water, water enters through the hole from outside to inside and from below upward. A chou (a graduated slip for sounding the water) is used to measure the water level: when the water reaches the mark for the hour of zi, it is the hour of zi; when it reaches the mark for the hour of wu, it is the hour of wu; when it reaches the mark for the first watch, it is the first watch. The other times are determined in the same way.

The Method of the Descending Clepsydra

Each day at dawn, as the sun is about to rise, the small basin is floated on the water in the large basin. By the time the sun sets, the small basin will of itself have filled with water and sunk to the bottom, and this is taken as the sign that the daylight of the day has ended. The small basin is then taken out, emptied, and set afloat again; by dawn the next day it will once more have sunk to the bottom. Both dusk and dawn are marked by the small basin filling and sinking, and these marks are used to fix the periods of day and night.

Each time the device is used, the water must first be filtered until it is clear, so that dust and impurities do not clog the small hole and the flow neither quickens nor slows.

The Method of Making the Chou

The chou may be made from a thin piece of wood or bamboo, shaped like a tally slip or a thin comb slat. The various times are marked on it according to the length required, and it is then used to sound the water level in order to determine the double-hours and the points of the night watches. The method is simple, and it is also comparatively clean.

Thin slips of wood or bamboo are made into tally-rods, shaped like a fine-toothed comb, and the hours are marked on them according to the graduated heights. The double-hours (shichen) and the night-watches (gengdian) are then calibrated by the method of “probing the water” (tanshui), which is especially simple and convenient. Each rod is thirty-four fen in all (ten li make one fen) and is divided equally into twelve segments, each of two fen and five li. Only the four positions Yin, Shen, Si, and Hai require an additional four fen; this is called the amount of “wei-pian-tian” (the supplement for the corner offsets). The accumulation of intercalary months forms the remainder over the course of a year; here this refers to the discrepancy produced in calendrical calculation. For the present only one convenient method is taken up: the position indicated by the floating fish (fuyu) is adopted as the standard. For the twelve months of the year, only twenty Taiping coins (Taiping qian) are used. They are increased or decreased according to the month and placed in a small basin to weigh it down.

The Method of Addition and Subtraction

At the solar term of the eleventh month, twenty Taiping coins are spread evenly over the bottom of the small basin by day, while an empty basin is used by night. At the solar term of the twelfth month, nineteen coins are used by day and one by night. Beginning with the solar term of the twelfth month, one coin is subtracted by day and one added by night every seven days.

At the solar term of the first month, eleven coins are used by day and nine by night; at the solar term of the second month, ten are used by day and ten by night; at the solar term of the third month, nine are used by day and eleven by night. Beginning with the solar term of the third month, one coin is subtracted by day and one added by night every seven days. At the solar term of the fourth month, one coin is used by day and nineteen by night; at the solar term of the fifth month, an empty basin is used by day and twenty coins by night; at the solar term of the sixth month, one coin is used by day and nineteen by night. Beginning with the solar term of the sixth month, one coin is added by day and one subtracted by night every seven days.

At the solar term of the seventh month, nine coins are used by day and eleven by night; at the solar term of the eighth month, ten are used by day and ten by night; at the solar term of the ninth month, eleven are used by day and nine by night. Beginning with the solar term of the ninth month, one coin is added by day and one subtracted by night every seven days. At the solar term of the tenth month, eleven coins are used by day and nine by night.

The Method of Reckoning the Directions of Sunrise and Sunset

In the first and ninth months, the sun rises in the Yi direction and sets in the Geng direction. In the second and eighth months, the sun rises in the Mao direction (the direction corresponding to the Rabbit) and sets in the You direction (the direction corresponding to the Rooster).

On the third day the crescent moon rises in the Yin direction and, at the end of the month, sets in the Yi direction.

In the first and ninth months the sun rises in the Yi direction and sets in the Geng direction; in the second and eighth months the sun rises in the Mao direction and sets in the You direction. In the third and seventh months the sun rises in the Jia direction and sets in the Xin direction; in the fourth and sixth months the sun rises in the Yin direction and sets in the Xu direction. In the fifth month the sun rises in the Gen direction and sets in the Qian direction; in the middle month of winter (usually the eleventh month of the lunar calendar) the sun rises in the Xun direction and sets in the Kun direction. Only in the tenth and twelfth months does the sun rise in the Chen direction and set in the Shen direction, and this must be carefully distinguished in the calculation.

The passage “In the third and seventh it issues from Jia and enters the land of Xin; in the fourth and sixth it arises at Yin and enters the Dog, once a day; add one wen by day and subtract one wen by night. At the nodal term of the tenth month, use eleven wen for the daytime and nine wen for the nighttime” is a mnemonic for reckoning, according to the seasons, the rising and setting of the sun and moon and the hours of day and night. Wen here is a unit of counting; exactly how it is converted should be understood together with the method of calculation in the original book.

“Jiuyang Zhenren” (the Perfected One of Nine Yang) is the title indicated here.