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卷五十五 志第七: 曆四

Volume 55 Treatises 8: Calendar 4

Chapter 55 of 元史 · History of Yuan
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1
From the Shoushi Calendar Canon, lower volume. Section 5: Computing Culminating Stars. At the Great Capital, the north celestial pole stands a little more than forty degrees above the horizon. At the winter solstice, the polar distance is 115° 21′ 73″.
2
At the summer solstice, the polar distance is 67° 41′ 13″. The length of the winter-solstice day and the corresponding summer-solstice night is 3,815 parts and 92 seconds. The length of the summer-solstice day and the corresponding winter-solstice night is 6,184 parts and 8 seconds. Twilight lasts 250 parts.
3
Polar distances as the ecliptic crosses inside and outside the equator, together with half day-and-night divisions Table omitted.〉 To find, for each day, the ecliptic's polar distance as it lies inside or outside the equator
4
滿 滿
Take the accumulated ecliptic longitude at midnight before dawn on the date in question. Divide by half the tropical year circumference and discard the quotient. If the remainder is below the quadrant limit, it is the initial limit; if it is above that limit, subtract half the tropical year circumference again; the remainder is the entry into the final limit; divide by the accumulated-degree period and take the remainder. Multiply the remainder by that segment's inside-outside difference, reduce by a factor of one hundred, and subtract the result from the tabulated inside-outside degree to obtain the degrees inside or outside the equator; subtract inside the equator and add outside it to the quadrant limit, and the result is the polar distance sought, in degrees, parts, and seconds.
5
To find, for each day, the half day-and-night division and the parts for sunrise, sunset, dawn, and dusk
6
滿 便
Take the entry into the initial or final limit for the date sought. Divide by the accumulated-degree period and discard the quotient. Multiply the remainder by the day-night difference, reduce by one hundred, and add or subtract the result to that segment's half day-and-night value to obtain the half day-and-night division for the day in question;) Subtract when the earlier value is larger and the later smaller; add when the earlier is smaller and the later larger. Treat the midnight division directly as the sunrise division. Subtract it from the day circumference; the remainder is the sunset division; subtract the twilight division from the sunrise division; the remainder is the dawn division; add the twilight division to the sunset division to obtain the dusk division.
7
To find the day-and-night divisions in ke and the double-hour ke of sunrise and sunset
8
Take the midnight division, double it, and reduce by one hundred to obtain the night ke; subtract that from one hundred ke; the remainder is the day ke; Apply the sunrise and sunset divisions according to the expansion-and-contraction procedure to obtain the sought double-hour ke. To find the watch and bell-stroke rates: take the dawn division, double it, and reduce by five to obtain the watch rate; reduce the watch rate by five again to obtain the bell-stroke rate.
9
To find the double-hour ke for each watch and bell-stroke
10
Take the watch or bell-stroke number sought, multiply it by the watch-and-bell rate, add the day's dusk division, and apply the expansion-and-contraction procedure to obtain the corresponding double-hour ke. To find the median-distance degree and the watch-interval degree
11
Take half the day circumference and subtract that day's dawn division; the remainder is the median-distance division; multiply by 366° 25′ 75″, divide by the day circumference, and the quotient is the median-distance in degrees; subtract that from 183° 12′ 87½″, double the result, and divide by five to obtain the watch-interval in degrees and parts.
12
To find the culminating stars at dusk, dawn, and each of the five night watches
13
宿 滿宿宿
Take the median-distance degree, add the sun's equatorial longitude at noon that day, and assign the lodge; that lodge is where the dusk culminating star stands—take it as the first-watch culminating star; add the watch-interval degree cumulatively for each watch; whenever the sum fills a full circuit of equatorial lodges, discard one circuit. This gives the lodge, degree, and parts for each watch and for dawn. For each of the nine domains, the day-and-night ke, parts, and all culminating-star rates are likewise derived from the local altitude of the north celestial pole. (The rates above agree of themselves with the results obtained from the gnomon-shadow and water-clock procedures.)
14
To find the clepsydra divisions for each of the nine domains
15
At each locality determine by instrument observation, or by setting up a water clock, the night ke at the winter or summer solstice for that place. Subtract it from fifty ke; the remainder is the solstice-difference ke. Take the ecliptic's degrees inside or outside the equator for the day sought, multiply by the solstice-difference ke, advance one decimal place, and divide by 239. Subtract the result inside the equator and add it outside, then apply that to fifty ke to obtain the night ke for the date in question; subtract the night ke from one hundred ke; the remainder is the day ke. (The double-hour ke of sunrise and sunset and the watch-and-bell rates are obtained by the procedures above.)
16
Section 6: Computing Conjunctions. Nodal period in parts: 272,122 parts and 24 seconds. Nodal period: 27 days, 2,122 parts, and 24 seconds. Half nodal period: 13 days, 6,061 parts, and 12 seconds.
17
Nodal inequality: 2 days, 3,183 parts, and 69 seconds. Synodic nodal interval from new moon to full moon: 14 days, 7,652 parts, and 96½ seconds. Nodal epoch constant: 260,187 parts and 86 seconds. Nodal period in degrees: 363° 79′ 34″.
18
Half nodal period in degrees: 181° 89′ 67″. Primary node longitude: 357° 64′. Median node longitude: 188° 05′. Solar eclipse limit on the solar side: 6°. Correction divisor: 60.
19
Lunar-side eclipse limit: 8°. Correction divisor: 80. Lunar eclipse limit: 13° 05′. Correction divisor: 87. To compute entry into the nodes at the Heavenly Standard month's canonical new moon
20
滿 滿 滿
Take the median accumulation, add the nodal epoch constant, and subtract the intercalary remainder. Divide by the nodal period in parts and discard the quotient; convert the remainder by the day circumference into days, with the leftover as parts and seconds. The result is the provisional day, parts, and seconds of nodal entry at the Heavenly Standard canonical new moon.) For retrospective calculation, add the intercalary remainder sought to the median accumulation and subtract the nodal epoch. Divide by the nodal period and discard the quotient; subtract the remainder from one full nodal period and proceed as above.
21
To find nodal entry for successive new and full moons
22
滿
Take the provisional nodal-entry day, parts, and seconds at the Heavenly Standard new moon and add the nodal synodic interval cumulatively for each subsequent syzygy. Whenever the sum fills a nodal period in days, discard one period. The remainder gives the provisional nodal entry for each following new or full moon. To find nodal entry at the fixed new and full moons and at midnight for each day
23
滿
For each syzygy, take the provisional nodal-entry day, parts, and seconds and subtract the canonical syzygy's small remainder to obtain nodal entry at the fixed syzygy's midnight. If the fixed date has been adjusted up or down, apply the same adjustment. Otherwise derive the fixed value from the canonical one: add two days after a long month and one day after a short month, and always add 7,877 parts and 76 seconds to the remainder to obtain nodal entry at the next new moon's midnight; add one day cumulatively for each following day; whenever the sum fills a nodal period in days, discard one period. This yields the provisional nodal entry at midnight for each day.
24
To find nodal entry at the true hour of each fixed new or full moon
25
Take the canonical syzygy's provisional nodal entry in days, parts, and seconds and add or subtract the fixed syzygy's time-correction difference to obtain nodal entry at the true hour of the fixed syzygy. To find the mean and true nodal longitudes
26
Multiply the canonical syzygy's provisional nodal entry in days, parts, and seconds by the moon's mean daily motion to obtain the mean nodal longitude; add the equation-of-center correction when in excess and subtract when in deficiency to obtain the true nodal longitude. To find the fixed time-parts for greatest eclipse of the sun or moon
27
退
For a solar eclipse: if the fixed new-moon division is below half the day circumference, subtract it from half the circumference to obtain the pre-noon interval; if it is above that, subtract half the circumference from it to obtain the post-noon interval; subtract the interval from half the circumference and multiply the two quantities, shift two decimal places, and divide by 96 to obtain the time correction; subtract the correction before noon and add it after noon to the fixed new-moon division to obtain the fixed division for greatest eclipse; add the time correction to the pre- or post-noon interval respectively to obtain the fixed distance-from-noon division.
28
退
For a lunar eclipse: if the fixed full-moon division is below one quarter of the day circumference, it is before mao, in early morning; if above that but still within the first half of the day, subtract from half the circumference to obtain the interval after mao; if below three quarters of the day circumference, subtract half the circumference to obtain the interval before you, in the evening; if above three quarters, subtract from the full day circumference to obtain the interval after you. Square the mao- or you-interval, shift two decimal places, and divide by 478 to obtain the time correction; subtract the correction before zi, at midnight, and add it after zi to the fixed full-moon division to obtain the fixed division for greatest eclipse; apply the expansion-and-contraction procedure to each to obtain the double-hour ke of greatest eclipse.
29
To find, at greatest eclipse, entry into the solar anomaly sequence and the true solar longitude
30
Take the canonical syzygy's entry into the anomaly sequence in days and parts, add the day and fixed parts to greatest eclipse, and subtract the canonical syzygy's day and parts to obtain the anomaly-sequence entry at greatest eclipse; by the solar-motion procedure find the equation-of-center correction, add it when in excess and subtract when in deficiency, to obtain the true solar longitude at greatest eclipse.
31
To find the north-south correction
32
滿退
For a solar eclipse, take the true solar longitude at greatest eclipse; if it is below the quadrant limit, it is the initial limit; if above the quadrant limit, subtract from half the tropical year circumference to obtain the final limit; square the initial or final limit, divide by 1,870 to obtain degrees, and convert any remainder into parts and seconds; subtract the result from 4° 46′ to obtain the provisional north-south correction; multiply the provisional correction by the fixed distance-from-noon division and divide by the half-day division; subtract the quotient from the provisional correction to obtain the fixed correction. If the provisional correction is smaller than the amount to be subtracted, reverse the subtraction to obtain the fixed correction, reversing the sign: add where subtraction was indicated and subtract where addition was indicated. When the sun is in excess at the initial limit and in deficiency at the final limit: before the node subtract on the lunar side and add on the solar side; after the node add on the lunar side and subtract on the solar side; When the sun is in deficiency at the initial limit and in excess at the final limit: before the node add on the lunar side and subtract on the solar side; after the node subtract on the lunar side and add on the solar side.
33
西
To find the east-west correction
34
滿退西
Take the true solar longitude at greatest solar eclipse, subtract it from half the tropical year circumference and multiply the two quantities, divide by 1,870 to obtain degrees, and convert any remainder into parts and seconds. The result is the provisional east-west correction; multiply by the fixed distance-from-noon division and divide by one quarter of the day circumference to obtain the fixed correction. If the provisional correction has already been exceeded, double the provisional correction and subtract it; the remainder is the fixed correction, to be added or subtracted accordingly. When in excess before the median point: before the node subtract on the lunar side and add on the solar side; after the node add on the lunar side and subtract on the solar side; after the median point: before the node add on the lunar side and subtract on the solar side; after the node subtract on the lunar side and add on the solar side. When in deficiency before the median point: before the node add on the lunar side and subtract on the solar side; after the node subtract on the lunar side and add on the solar side; after the median point: before the node subtract on the lunar side and add on the solar side; after the node add on the lunar side and subtract on the solar side.
35
To find the limit degrees for a solar eclipse at the primary and median nodes
36
西
Take the primary-node and median-node longitudes, add or subtract the north-south and east-west corrections, and obtain the limit degrees, parts, and seconds for the primary and median nodes. To find, for a solar eclipse, entry into the solar or lunar side and the degrees before or after the node
37
Take the true nodal longitude; if it is below the median-node limit, subtract it from that limit to obtain the solar-side degrees before the node; if above the limit, subtract the median-node limit to obtain the lunar-side degrees after the node; if below the primary-node limit, subtract from that limit to obtain the lunar-side degrees before the node; if above the primary-node limit, subtract that limit to obtain the solar-side degrees after the node.
38
To find, for a lunar eclipse, entry into the solar or lunar side and the degrees before or after the node
39
Take the true nodal longitude; if it is below the median-node degree, it is on the solar side; if above the median-node degree, subtract the nodal median to obtain the lunar side. For entry into the solar or lunar side, if below the rear standard of 15°30′, it is after the node; if above the front standard of 166°39′68″, subtract from the nodal median to obtain the degrees and parts before the node.
40
To find the magnitude of a solar eclipse in parts and seconds
41
Take the degrees before or after the node and subtract the eclipse limit for the solar or lunar side, If the remainder is insufficient to subtract, there is no eclipse.〉 divide each remainder by the correction divisor to obtain the parts and seconds of the solar eclipse. To find the magnitude of a lunar eclipse in parts and seconds
42
西
Take the degrees before or after the node,) without applying the north-south or east-west corrections. Subtract the eclipse limit, If the remainder is insufficient to subtract, there is no eclipse.〉 divide the remainder by the correction divisor to obtain the parts and seconds of the lunar eclipse. To find the fixed duration of a solar eclipse and the three contact times in double-hour ke
43
Take the parts and seconds of the solar eclipse, subtract them from twenty parts and multiply the two quantities, extract the square root, multiply by 5,740, and divide by the limit-entry motion in degrees to obtain the fixed-duration division; subtract from the fixed division at greatest eclipse to obtain first contact; add to the fixed division at greatest eclipse to obtain last contact; apply the expansion-and-contraction procedure to obtain the three contact times of the solar eclipse in double-hour ke.
44
To find the fixed duration of a lunar eclipse and the three or five contact times in double-hour ke
45
Take the parts and seconds of the lunar eclipse, subtract them from thirty parts and multiply the two quantities, and extract the square root; multiply the result by 5,740 and divide by the limit-entry motion in degrees to obtain the fixed-duration division; subtract from the fixed division at greatest eclipse to obtain first contact; add to the fixed division at greatest eclipse to obtain last contact; apply the expansion-and-contraction procedure to obtain the three contact times of the lunar eclipse in double-hour ke.
46
For a total lunar eclipse, subtract the within-totality division from ten parts and multiply the two quantities, extract the square root, multiply by 5,740, and divide by the limit-entry motion in degrees to obtain the within-totality division; subtract that from the fixed-duration division to obtain the outside-totality division; subtract the fixed-duration division from the fixed division at greatest eclipse to obtain first contact; add the outside-totality division to obtain the onset of totality; add the within-totality division again to obtain greatest eclipse; add the within-totality division once more to obtain emergence from totality; add the outside-totality division again to obtain last contact; apply the expansion-and-contraction procedure to obtain the five contact times of the lunar eclipse in double-hour ke.
47
To find which night watch and bell-stroke a lunar eclipse falls in
48
滿
Take the dawn division of the day on which greatest eclipse occurs, double it, and reduce by five to obtain the watch divisor; reduce the watch divisor by five again to obtain the bell-stroke divisor. Then take the initial and final divisions: if above the dusk division, subtract the dusk division; if below the dawn division, add the dawn division. Divide by the watch divisor to obtain the watch number; convert any remainder by the bell-stroke divisor to obtain the bell-stroke number; Assign the watch and bell-stroke numbers starting from the first watch and first bell-stroke outside the count to determine which watch and bell-stroke each contact falls in.
49
To find the direction in which a solar eclipse begins
50
西 西 西
If the eclipse is on the solar side, it first appears in the southwest, reaches maximum due south, and ends in the southeast; if on the lunar side, it first appears in the northwest, reaches maximum due north, and ends in the northeast; if the eclipse magnitude is eight-tenths or greater, it begins due west and ends due east. This is stated with reference to the noon meridian.〉
51
To find the direction in which a lunar eclipse begins
52
西 西 西
If the eclipse is on the solar side, it first appears in the northeast, reaches maximum due north, and ends in the northwest; if on the lunar side, it first appears in the southeast, reaches maximum due south, and ends in the southwest; if the eclipse magnitude is eight-tenths or greater, it begins due east and ends due west. This too is stated with reference to the noon meridian.〉
53
To find the magnitude visible when the sun or moon rises or sets during an eclipse
54
滿 退 退
If that day's sunrise or sunset division falls after first contact and before greatest eclipse, the eclipse is visible at rising or setting. For each case subtract the sunrise or sunset division from the greatest-eclipse division; the remainder is the rising-or-setting eclipse difference; multiply by the eclipse magnitude and divide by the fixed-duration division, For a total lunar eclipse, subtract the within-totality division from the rising-or-setting difference, advance the remainder one decimal place, and divide by the outside-totality division. Subtract the quotient from the totality division to obtain the magnitude seen when the moon rises or sets in eclipse; if the subtraction cannot be completed, the eclipse is total at rising or setting.〉 subtract that from the eclipse magnitude to obtain the magnitude visible at sunrise or sunset. If greatest eclipse occurs in daytime, at dawn the eclipse is still advancing and at dusk it has already retreated; if greatest eclipse occurs at night, at dawn it has already retreated and at dusk it is still advancing.〉
55
宿
To find the lodge and degree at greatest solar or lunar eclipse
56
便 宿
Take the true solar longitude at greatest eclipse; if in excess, use it directly as the fixed accumulation; if in deficiency, add half the tropical year circumference to obtain the fixed accumulation. For a full moon, add half the celestial circumference in degrees as well. Add the fixed accumulation to the ecliptic solar longitude at the hour of the Heavenly Standard winter solstice and assign the lodge to obtain the lodge, degree, and parts at greatest eclipse for the sun or moon.
57
Section 7: Computing the Five Planets. Circumference: 365° 25′ 75″. Half circumference:
58
182° 62′ 87½″. Circumference stride: 15° 21′ 90″ 62½ microparts. Jupiter
59
Orbital period in parts: 3,988,800 parts. Sidereal period: 398 days and 88 parts. Epicycle rate: 43,312,964 parts and 86½ seconds. Degree rate: 118,582 parts.
60
Conjunction epoch constant: 1,179,726 parts. Sequence epoch constant: 18,999,481 parts. Established excess-deficiency difference: add 236. Mean difference: subtract 25,912.
61
Fixed difference: 10,897,000. Arc of visibility at heliacal setting/rising: 13°. Table omitted.〉 Mars
62
Orbital period in parts: 7,799,290 parts. Sidereal period: 779 days, 92 parts, 90 seconds. Epicycle rate: 6,869,580 parts and 43 seconds. Degree rate: 18,807½ parts.
63
Conjunction epoch constant: 567,545 parts. Sequence epoch constant: 5,472,938 parts. Established difference for the excess-initial, deficiency-final arc: subtract 1,135. Mean difference: subtract 831,189.
64
Fixed difference: 88,478,400. Established difference for the deficiency-initial, excess-final arc: add 851. Mean difference: negative subtraction of 30,235. Fixed difference: 29,976,300.
65
Arc of visibility at heliacal setting/rising: 19°. Table omitted.〉 Saturn orbital period in parts: 3,780,916 parts.
66
Sidereal period: 378 days, 9 parts, 16 seconds. Epicycle rate: 174,788,845 parts and 66 seconds. Degree rate: 294,255 parts. Conjunction epoch constant: 175,643 parts.
67
Sequence epoch constant: 52,240,561 parts. Established excess difference: add 283. Mean difference: subtract 41,022. Fixed difference: 15,146,100.
68
Established deficiency difference: add 331. Mean difference: subtract 15,126. Fixed difference: 11,117,500. Arc of visibility at heliacal setting/rising: 18°.
69
Table omitted.〉 Venus orbital period in parts: 5,839,026 parts. Sidereal period: 583 days, 90 parts, 26 seconds.
70
Epicycle rate: 3,652,575 parts. Degree rate: 10,000 parts. Conjunction epoch constant: 5,716,330 parts. Sequence epoch constant: 119,639 parts.
71
Established excess-deficiency difference: add 141. Mean difference: subtract 3. Fixed difference: 3,515,500. Arc of visibility at heliacal setting/rising: 10½°.
72
Table omitted.〉 Mercury orbital period in parts: 1,158,760 parts. Sidereal period: 115 days, 87 parts, 60 seconds.
73
Epicycle rate: 3,652,575 parts. Degree rate: 10,000 parts. Conjunction epoch constant: 700,437 parts. Sequence epoch constant: 2,055,161 parts.
74
Established excess-deficiency difference: add 141. Mean difference: subtract 2,165. Fixed difference: 3,877,000. Arc of visibility at morning hiding and evening appearance: 16½°.
75
Arc of visibility at evening hiding and morning appearance: 19°. Table omitted.〉 To compute, after the Heavenly Standard winter solstice, the median accumulation and median star for each planet's mean conjunction and for every phase.
76
退 滿便
Take the median accumulation, add the conjunction epoch, divide by that planet's orbital period in parts, and the remainder is the prior conjunction interval; then subtract the orbital period once more; the remainder is the later conjunction interval; Reduce by the day circumference to obtain the median accumulation and median star for that planet's mean conjunction after the Heavenly Standard winter solstice. When named as days, this is the median accumulation; when named as degrees, it is the median star.〉 Accumulate the phase-day intervals onto the median accumulation to obtain each phase's median accumulation; Accumulate mean degrees onto the median star, subtracting where retrograde motion occurs, to obtain each phase's median star. For backward calculation, subtract the conjunction epoch from the median accumulation, divide by the orbital period, and the remainder is the later-conjunction fraction sought.〉
77
To compute entry into the epicycle for each planet's mean conjunction and for every phase.
78
滿 滿退 滿
For each planet, take the median accumulation, add the sequence epoch and the later-conjunction fraction sought, and divide by the epicycle rate; The remainder, divided by the degree rate, gives degrees and parts for that planet's mean-conjunction entry into the epicycle; Add the phase limits successively to obtain each phase's entry into the epicycle. For backward calculation, subtract the sequence epoch from the median accumulation, divide by the epicycle rate, subtract the remainder from the epicycle rate, add the result to that year's later conjunction, and proceed as above.〉
79
To find the excess-deficiency correction.
80
Take the entry into the epicycle in degrees and parts; if it is at or below half the epicycle, the motion is in excess; If above, subtract half the epicycle; the remainder is the deficiency arc. On the excess-deficiency epicycle, if the excess arc is at or below 91° 31′ 43″ excessive, this is the initial limit; If above, subtract from half the epicycle; the remainder is the final limit.
81
For Mars, on the excess arc, if at or below 60° 87′ 62½″, this is the initial limit; If above, subtract from half the epicycle; the remainder is the final limit. On the deficiency arc, if at or below 121° 75′ 25″, this is the initial limit; If above, subtract from half the epicycle; the remainder is the final limit.
82
滿滿退
Take each planet's established difference, multiply by the initial or final limit, and use the result to add or subtract the mean difference; repeat with the fixed difference; multiply again by the initial or final limit, divide by 100 million to obtain degrees and parts, and the result is the excess-deficiency correction sought.
83
Alternate method: take the position on the excess-deficiency epicycle, divide by the sequence stride to get the stride count and remainder; Multiply the remainder by the tabulated rate for that stride, divide by the sequence stride, and add or subtract from the accumulated correction at the lower stride to obtain the same excess-deficiency correction. To find the true accumulation for mean conjunction and for each phase.
84
滿滿
For each planet and phase, take the median accumulation and apply the excess-deficiency correction—adding if in excess, subtracting if in deficiency—to obtain the true accumulation in days and parts; Add the Heavenly Standard winter solstice date and time, reduce modulo the era divisor, and assign the day and hour from the sexagenary cycle. To find the month and day on which mean conjunction and each phase occur.
85
滿
Take the true accumulation for each phase, add the intercalary offset from the Heavenly Standard new year, divide by the new-moon stride to get the month count and the elapsed days within the month. Count months forward from the Heavenly Standard eleventh month to obtain the days and parts within the month since the new moon for that phase; Combine with the assigned day and hour to obtain the calendar month and day of occurrence.
86
To find the true planetary longitude at the hour of mean conjunction and for each phase.
87
宿
For each phase, take the median star and apply the excess-deficiency correction—adding when in excess and subtracting when in deficiency— (Double the correction for Venus; triple it for Mercury.) to obtain the true star for every phase; Add the Heavenly Standard winter solstice ecliptic longitude at the hour of occurrence and assign the lodge position; the result is that planet's ecliptic lodge-degree and parts at the hour of that phase.
88
To find the true planetary longitude at midnight before dawn on the first day of each phase.
89
退
For each phase, multiply the initial motion rate by the fractional hour of occurrence, divide by one hundred, then subtract for prograde motion or add for retrograde motion from that day's true longitude at the hour of occurrence; the result is the true longitude at midnight before dawn on the first day of the phase; Add and assign the lodge position as before to obtain the value sought. To find the day rate and degree rate for each phase.
90
宿宿
For each phase, take the elapsed days and hours to the next phase as the day rate, and the difference between midnight lodge positions of the two phases as the degree rate. To find the uniform daily motion for each phase, divide the degree rate by the day rate to obtain the mean daily motion in degrees and parts.
91
To find the variation correction and daily increment for each phase.
92
退
Subtract the uniform motion rates at the boundaries of the phase; the result is the phase's general difference; Double the result and shift the decimal place; this is the variation correction; Add or subtract it from the phase's uniform motion rate to obtain the daily motion on the first and last days.) If the earlier rate exceeds the later, add the correction at the start and subtract at the end; If the earlier rate is less than the later, subtract at the start and add at the end. Double the variation correction to obtain the total difference; Divide by the day rate minus one to obtain the daily increment.
93
退
To find the variation correction for stationary-hidden, slow, and retrograde phases: for a prior stationary-hidden phase, take the next phase's first-day motion rate, add half the daily increment, and the result is the last day's motion rate.
94
For a later stationary-hidden phase, take the prior phase's last-day motion rate, add half the daily increment, and the result is the first day's motion rate; Subtract this from the stationary-hidden phase's uniform motion rate; the remainder is the variation correction. For a prior slow-motion phase, take the prior phase's last-day motion rate, subtract twice the daily increment, and the result is the first day's motion rate.
95
退退
For a later slow-motion phase, take the next phase's first-day motion rate, subtract twice the daily increment, and the result is the last day's motion rate; Subtract this from the slow-motion phase's uniform motion rate; the remainder is the variation correction.) This applies to slow-motion segments adjacent to a station. For Jupiter, Mars, and Saturn in retrograde, multiply the uniform motion rate by six and shift the decimal place; the result is the variation correction.
96
退退 退
For Venus in retrograde stationary-hidden phases before and after, multiply the uniform motion rate by three, halve, and shift the decimal place to obtain the variation correction. For a prior retrograde phase, take the next phase's first-day motion rate, subtract the daily increment, and the result is the last day's motion rate.
97
退
For a later retrograde phase, take the prior phase's last-day motion rate, subtract the daily increment, and the result is the first day's motion rate; Then subtract this from the phase's uniform motion rate; the remainder is the variation correction.
98
退
For Mercury in retrograde, take half the uniform motion rate as the variation correction; In every case, add or subtract the variation correction from the uniform motion rate to obtain the daily motion on the first and last days. If the earlier rate exceeds the later, add the correction at the start and subtract at the end; If the earlier rate is less than the later, subtract at the start and add at the end. Again double the variation correction to obtain the total difference; Divide by the day rate minus one to obtain the daily increment.
99
宿
To find each day's planetary lodge position at midnight before dawn.
100
退滿宿宿
For each phase, start from the first-day motion rate and adjust cumulatively by the daily increment—subtracting when the later rate is smaller, adding when it is larger—to obtain each day's motion in degrees and parts; Then add for prograde motion and subtract for retrograde, removing one lodge span whenever the sum is full; the result is the planetary lodge position at midnight before dawn for each day. To find entry into the excess-deficiency epicycle for each planet's mean conjunction, appearance, and stationary-hidden phases.
101
滿 滿
Take the true accumulation in days and parts for that planet and phase, (If the value fills a full tropical year in days and parts, discard one year; the remainder falls after the next year's Heavenly Standard winter solstice.) If it is at or below half a tropical year, the planet is on the excess arc; When it fills half a tropical year, discard that amount; the planet is on the deficiency arc; If the position is at or below the initial limit, it falls within the initial limit; If above, subtract half a tropical year; the remainder gives the position within the final limit; This yields the days and parts of entry into the excess-deficiency epicycle for each planet's mean conjunction, appearance, and stationary-hidden phases.
102
To find the relative motion for each planet's mean conjunction, appearance, and stationary-hidden phases.
103
退退
For each planet and phase, subtract the Sun's first-day motion rate from the planet's first-day motion rate; the remainder is the relative motion. If Venus or Mercury is retrograde at retrograde conjunction, add the planet's first-day motion rate to the Sun's first-day motion rate to obtain the relative motion; For Mercury in its evening stationary-hidden, morning-appearance configuration, take the Sun's first-day motion rate directly as the relative motion.
104
To find the provisional true accumulation for fixed conjunction, appearance, and stationary-hidden phases of the five planets.
105
便
For Jupiter, Mars, and Saturn, the true accumulation day for mean conjunction with morning appearance and evening stationary hidden serves directly as the provisional true accumulation for conjunction, stationary hidden, and appearance.
106
滿退 退
For Venus and Mercury, take the excess-deficiency correction in degrees and parts for that phase, (Double the value for Mercury.) Divide by the relative motion for that phase to convert to days, with the remainder as parts and seconds. For mean conjunction with evening appearance and morning stationary hidden, subtract when in excess and add when in deficiency; For retrograde conjunction with evening stationary hidden and morning appearance, add when in excess and subtract when in deficiency; Apply the correction to the true accumulation to obtain the provisional true accumulation for fixed conjunction, stationary hidden, and appearance in days and parts.
107
To find the true accumulation and true longitude for fixed conjunction of the five planets.
108
滿退
For Jupiter, Mars, and Saturn, divide the first-day solar excess-deficiency accumulation by the mean-conjunction relative motion to obtain the days of separation-from-conjunction correction; Convert the remainder to parts and seconds, then subtract from the solar excess-deficiency accumulation to obtain the degrees of separation-from-conjunction correction. Take the provisional true accumulation for fixed conjunction and apply the days of separation-from-conjunction correction—subtracting when in excess and adding when in deficiency—to obtain the true accumulation in days and parts; Apply the degrees of separation-from-conjunction correction—subtracting when in excess and adding when in deficiency—to obtain the true longitude at fixed conjunction in degrees and parts.
109
退退 滿退退 退退退 退 滿 滿宿宿 宿 宿 退宿宿宿退宿退
For Venus and Mercury at direct or retrograde conjunction, divide that day's solar excess-deficiency accumulation by the appropriate relative motion to obtain the days of separation-from-conjunction correction; Convert the remainder to parts and seconds, then add for direct motion or subtract for retrograde motion from the solar excess-deficiency accumulation to obtain the degrees of separation-from-conjunction correction. For direct conjunction, add when in excess and subtract when in deficiency from the provisional true accumulation to obtain the true accumulation in days and parts; For retrograde conjunction, apply the days correction by subtracting when in excess and adding when in deficiency, and the degrees correction by adding when in excess and subtracting when in deficiency, to the provisional retrograde true accumulation to obtain the true accumulation in days and parts; Assign the lodge position to obtain the true longitude at retrograde fixed conjunction in degrees and parts. Add the Heavenly Standard winter solstice date and time to the true accumulation for fixed conjunction, reduce modulo the ten-day cycle, and assign the day and double-hour from the sexagenary cycle to obtain the calendar date and time of fixed conjunction. Add the Heavenly Standard winter solstice ecliptic longitude at the hour of occurrence to the true longitude at fixed conjunction, reducing modulo one lodge span, to obtain the ecliptic lodge-degree and parts where the fixed conjunction occurs. (To determine fixed conjunction and stationary-hidden days directly: for Jupiter, Mars, and Saturn, subtract the planet's midnight ecliptic lodge position from the midnight ecliptic solar longitude; if the remainder is at or below the Sun's daily motion, that day is the stationary-hidden conjunction; For Venus and Mercury, subtract the midnight ecliptic solar longitude from the planet's midnight ecliptic lodge position; if the remainder is at or below the planet's daily motion, that day is the stationary-hidden conjunction. (For Venus and Mercury in stationary-hidden retrograde conjunction, check whether at midnight the Sun's ecliptic lodge position has not yet reached the planet's lodge position; then on the next day, when the Sun passes the planet's lodge position and the planet in retrograde passes the Sun's lodge position, that day is the fixed retrograde conjunction and stationary-hidden date.)
110
To find the true accumulation for fixed appearance and stationary hidden of Jupiter, Mars, and Saturn.
111
滿滿滿退 滿退
Take the provisional true accumulation for fixed appearance and stationary hidden; add ninety-one days 31 parts 6 seconds for morning appearance and subtract for evening stationary hidden; if at or below half a tropical year, square the value, otherwise subtract the tropical year and square the remainder; divide by seventy-five for parts and by one hundred for degrees, with the remainder as seconds; Multiply by the planet's appearance-and-stationary-hidden arc and divide by fifteen; Divide the result by the relative motion for that phase to convert to days, with the remainder as parts and seconds; Add for appearance and subtract for stationary hidden from the provisional accumulation to obtain the true accumulation for fixed appearance and stationary hidden in days and parts; Add and assign the day and hour as before to obtain the calendar date and time of fixed appearance and stationary hidden.
112
To find the true accumulation for fixed appearance and stationary hidden of Venus and Mercury.
113
滿退 滿滿退
For each phase, divide the first-day solar excess-deficiency accumulation by the daily relative motion for stationary hidden and appearance to obtain days, with the remainder as parts and seconds; For evening appearance and morning stationary hidden, add when in excess and subtract when in deficiency; For morning appearance and evening stationary hidden, subtract when in excess and add when in deficiency; Apply the correction to the provisional true accumulation for fixed appearance and stationary hidden to obtain the regular accumulation. If at or below half a tropical year, the date falls after the winter solstice; If above, subtract half a tropical year; the remainder falls after the summer solstice. If the value is at or below ninety-one days 31 parts 6 seconds, square it; if above, subtract half a tropical year and square the remainder. For morning appearances after the winter solstice and evening appearances after the summer solstice, divide by eighteen to obtain parts; For evening appearances after the winter solstice and morning appearances after the summer solstice, divide by seventy-five to obtain parts; Multiply again by the planet's appearance-and-stationary-hidden arc and divide by fifteen; Divide the result by the relative motion to convert to days, with the remainder as parts and seconds, then add or subtract from the regular accumulation to obtain the true accumulation. For morning appearance and evening stationary hidden, add the correction after the winter solstice and subtract after the summer solstice; For evening appearance and morning stationary hidden, apply the correction by subtracting after the winter solstice and adding after the summer solstice; this gives the true accumulation in days and parts for fixed appearance and stationary hidden; Add and assign the day and hour as before to obtain the calendar date and time of fixed appearance and stationary hidden.
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