第三部·第二十八至二十九则　上升点向诸光线与五分诸相

CANON XXVIII.

第二十八则。

To direct the Oblique Cardinal Sign to the Sextile, Quartile, and Trine.

斜的角向六分、四分与三分的推运。

If you require the rays to the horoscope, which are projected from supra-terraneous places, divide the semi-diurnal arc of the aspecting star into three parts, or into two diurnal horary times, and you will have the spaces of the houses that are about the earth. If you add two of these to the stars oblique ascension, taken in the horoscope, and from the sum substract the horoscope oblique ascension, what remains is the horoscope's arc of direction to the sextile's of the stars, produced from the eleventh house; but if you add the four houses, and from the sum substract the horoscope's oblique ascension, you will have the arc of direction to the trine which is caused by the ninth house.

若你要求向上升点的光线，即从地上诸位置投射来的，就把成相位之星的半昼弧分成三份，或者说，分成每份两个昼时量，便得地平以上诸宫的空间。若把其中两份加到在上升点所取的星的斜升上，再从和数中减去上升点的斜升，所剩就是上升点向由第十一宫发出的星之六分的推运弧；若加四宫，再从和数中减去上升点的斜升，便得向由第九宫发出的三分的推运弧。

Another way.—Substract one house from the stars right ascension, and from the remainder take the right ascension of the medium cœli, and there will remain the direction's arc to the sextile's; add one house to the stars right ascension; from the sum substract that of the medium cœli, and you will have the direction's arc to the trine, that is, to the horoscope.

另一法。——从星的赤经中减去一宫，再从余数中减去中天的赤经，所剩就是向六分的推运弧；把一宫加到星的赤经上，再从和数中减去中天的赤经，便得向三分的推运弧，即向上升点的三分。

But if you are desirous to find the rays that are emitted from subterraneous places, divide the stars semi-nocturnal arc into three equal parts, its nocturnal horary times, and you will have the space of the houses that are below the earth; of these, for the sextile, which proceeds from the third house, by substracting two; and from the trine, which is produced from the fifth, by substracting four from the stars oblique ascension taken in the horoscope; and if from the remainders you substract the horoscope's oblique ascension, you will have the arcs of direction to the sextile and trine.

但若你想求从地下诸位置发出的光线，就把星的半夜弧分成三等分，即它的夜时量，便得地平以下诸宫的空间；其中，为由第三宫发出的六分，减去两份；为由第五宫产生的三分，从在上升点所取的星的斜升中减去四份；若从余数中减去上升点的斜升，便得向六分与三分的推运弧。

You may also use the imum cœli by the right ascension, as has been said of the medium cœli. Quadrate rays are produced by the medium cœli and the imum cœli; therefore, instead of these, direct the stars to the medium and imum cœli, as has been said in Canon XXVI. Let there be an example for both Canons, under the Pole's elevation 45, the ascendant 13.30 of ♑, in the medium cœli. Let us suppose 12° 0' of ♏, whose right ascension 219.33, the horoscope's oblique ascension 309.33.

你也可以像对中天所说的那样，借赤经使用天底。四分的光线由中天与天底产生；所以不用求四分，只要像第二十六则所说，把星推到中天与天底即可。两则共用一个例子：极高四十五度，上升在摩羯十三度三十分，中天，我们设在天蝎十二度零分，其赤经二百一十九度三十三分，上升点的斜升三百零九度三十三分。

If the Sun is in 1° 0' of ♑, within the twelfth house, the Sun's right ascension 271° 5', the oblique ascension to the Pole 45, is 296.51 ; the diurnal horary times 10° 42', which, being doubled, constitute the diurnal houses, or the third part of the Sun's semi-diurnal 21° 24'. But if I want to direct the horoscope to the sextile of the Sun, I add to the oblique ascension, to the Sun's horary times, twice doubled, which make 339.39. From these I substract the horoscope's oblique ascension, and there remains the arc of direction 30° 6'.

若太阳在摩羯一度零分，位于第十二宫内，太阳的赤经二百七十一度五分，在极高四十五度下的斜升是二百九十六度五十一分；昼时量十度四十二分，加倍就构成昼宫，即太阳半昼弧的三分之一，二十一度二十四分。但若我要把上升点推向太阳的六分，就把太阳的时量两次加倍，加到斜升上，得三百三十九度三十九分。从中减去上升点的斜升，余下推运弧三十度六分。

And observe, that the arc of direction consists of 8° 44' of the preceding, and likewise of the Sun's duplicate horary times; that is, one house, or 21.24. Wherefore, from the bare adding of this one house to the computed direction of the sextile to the medium cœli, there arises the horoscope's arc of direction to the Sun's sextile.

而且要注意，这个推运弧由前面的八度四十四分，加上太阳的双倍时量，即一宫，二十一度二十四分构成。所以，只要把这一宫加到所算出的中天向六分的推运上，就得出上升点向太阳六分的推运弧。

I want to direct to the horoscope to the quintile of the Sun: I substract the right ascension of the medium cœli from that of the Sun, and there remains the arc of direction, 51.32; or to the sextile's arc of direction 30.6, above calculated. I add the sun's duplicate diurnal horary times 21.24, and the arc of direction 51.30. In like manner, if to this I add the duplicate, horary times, I make the arc of direction to the trine of the horoscope, 72.54.

我要把上升点推向太阳的五分：从太阳的赤经中减去中天的赤经，余下推运弧五十一度三十二分；或者在上面算出的六分推运弧三十度六分上，加上太阳的双倍昼时量二十一度二十四分，得推运弧五十一度三十分。同样，若再加上双倍时量，就得上升点的三分的推运弧，七十二度五十四分。

Again I add to this the geminated horary times; the direction's arc to the medium cœli, to the Sun's sextile, will be 94.18, and so in all of them. Under the Earth, we must make use of the nocturnal horary times, the same nocturnal arc, but the direction both of the cardinal signs and houses to the rays of the sextile, quartile, and trine, are calculated (in a manner much easier than any of the afore-mentioned) by the oblique ascension of those houses from which the stars project the rays, as is before recited, and as may be seen in the former Canon. This Canon needs no other example, nevertheless you will meet with several in the sequil.

再加上成双的时量，中天向太阳六分的推运弧将是九十四度十八分，其余一切都如此。在地下，必须用夜时量、同样的夜弧；不过四角与诸宫向六分、四分、三分光线的推运，都可借星投射光线所自的那些宫的斜升来算（比前述任何方法都容易得多），如前所述，也可见于上一则。本则不需要别的例子，不过在后面你会遇到好几个。

CANON XXIX.

第二十九则。

To direct the Cardinal Signs to the Rays of the Quintile or Sesqui-quadrate and Biquintile.

四角向五分或倍半四分与倍五分光线的推运。

Beside the usual rays of the ⚹, □, △, and ☍, I only suppose the quintile, sesqui-quadrate, and biquintile, to be powerful, as experience evinces from the symmetrical concerts of sound, from which the very excellent Kepler, in a most exquisite manner of resemblance, collects the rays of the stars in the heavens, Whatever may be the opinion of others with regard to the semi-sextile, semi-quadrate, and several others, to which it seems quite absurd to assign any efficacy, (with this one exception) I confess, that in the same quadrate's distances, sounds begin to arrive at a degree of harmony, but altogether imperfect to this, therefore some portion of efficacy may be attributed; and on this principle I think that neither the Sun nor Moon become the prorogation of life, except they be semi-quadrate distance from the horoscope, or half of their semi-diurnal arc.

除了通常的六分、四分、三分与对冲诸光线，我只认为五分、倍半四分与倍五分有力，这是经验从声音的对称和谐中证明的；杰出的开普勒正是由此，以极精妙的类比，汇集天上星辰的光线。无论别人对半六分、半四分以及其他若干相位意见如何，给它们指派任何效力在我看来都十分荒谬（只有一个例外），我承认，在同一四分的距离上，声音开始达到某种程度的和谐，但比起这个全然不完美，因此可以给它一些效力；根据这个原理，我认为太阳与月亮都不成为生命的释放者，除非它们离上升点有半四分的距离，即它们半昼弧的一半。

Above it, we may easily calculate the sesqui-quadrate ray to the cardinal signs, for it consists of the quarter of the world, and half of another quarter; or of the semi-diurnal or nocturnal arc; and also of half of the same, or another, so that the stars have this ray to the medium cœli, and the east, in the mean distance between the west and imum cœli; to the medium cœli and west, in the mean distance from the imum cœli to the east; to the west and imum cœli, in the middle between the east and the medium cœli, to the imum and east; in the middle, between the medium and the west.

在上述基础上，我们很容易算出向四角的倍半四分光线，因为它由世界的一个象限加另一象限的一半构成；即由半昼弧或半夜弧，再加上同一个或另一个的一半构成；所以星辰与中天和东方成这光线时，位于西方与天底的正中间；与中天和西方成这光线时，位于天底到东方的正中间；与西方和天底成这光线时，位于东方与中天的正中间；与天底和东方成这光线时，位于中天与西方的正中间。

For the calculation, divide the semi-diurnal arc into two equal parts; or as occasion requires, the semi-nocturnal of the stars, and this half part is the secondary distance from both the cardinal signs, as beforementioned.—In the example of the former Canon, the Sun forms the sesqui-quadrate to the west, and to the imum cœli, when it is the mean distance between the east and medium cœli, the Sun's semi-diurnal arc is 64.12, the half of this 32.6; wherefore I substract this secondary distance from the primary, which is betwixt it and the medium cœli, being 51.32, and there remains the arc of direction 19.26.

计算时，把星的半昼弧，或视情况把半夜弧，分成两等分，这一半就是离两个角的次距，如前所述。——在上一则的例子中，太阳位于东方与中天的正中间时，与西方和天底成倍半四分；太阳的半昼弧是六十四度十二分，一半是三十二度六分；所以我从它与中天之间的初距五十一度三十二分中减去这个次距，余下推运弧十九度二十六分。

But as this secondary distance, as well from the preceding as the succedent cardinal house, is the same, the Sun's primary distance from the east is 12.40. I substract this from the secondary, and the remainder is the same arc of direction, 19.26.

但因为这个次距，无论从前面的还是后面的角宫量，都相同，而太阳离东方的初距是十二度四十分，我从次距中减去它，余数是同一个推运弧，十九度二十六分。

Likewise, half the same semi-diurnal arc consists of the triplicate horary times; wherefore, if we add the Sun's horary times to its distance from the twelfth house, which was the arc of direction of the medium cœli to the Sun's ⚹, that is. 8.44, the Sun's horary times are 10.42; the sum is the arc of direction 19.26.

同样，同一半昼弧的一半由三个时量构成；所以，若把太阳的时量加到它离第十二宫的距离上，这距离就是中天向太阳六分的推运弧，即八度四十四分，太阳的时量是十度四十二分，和数就是推运弧十九度二十六分。

You see, therefore, there are several ways of directing the angles to the aspects of the stars; but to calculate the rays quintile and biquintile with ease and exactness, we must understand the Pentagonal figure in the opposite plate, wherein the point A may represent any cardinal sign of the world, or any other significator to be directed to the quintile and biquintile: the points F, G, H, are the other three cardinal signs;

由此你看到，把四角推向诸星的相位有好几种方法；但要轻松而精确地计算五分与倍五分光线，就必须理解对页图版上的五边形图：其中甲点可代表世界的任何一个角，或任何别的要推向五分与倍五分的征象星；己、庚、辛三点是另外三个角；

B is the end of the quintile, C of the biquintile, D the point of another quintile, E of another biquintile, and F of the opposition; the fourth AG, CF, FH, HA, are the quadrates or quarters of the world, or arcs, which, by the stars in those quarters, are semi-diurnal or semi-nocturnal, which may be various in quantity, according to the variety of the declination of the stars, and altitude of the pole.

乙是五分的终点，丙是倍五分的终点，丁是另一个五分之点，戊是另一个倍五分之点，己是对冲之点；第四，甲庚、丙己、己辛、辛甲，是世界的四分或四个象限，即诸弧，按照位于这些象限中的星，是半昼弧或半夜弧，其数量可以各不相同，随星的赤纬与天极高度的不同而变。

If the point A may be said to be the medium cœli, divide the semi-diurnal arc of the aspecting star into five equal parts, four of which constitute the ray quintile, both in points D and B: also let the semi-nocturnal arc be divided into five equal parts; three parts after adding the whole semi-diurnal arc, constitute the biquintile rays in the point E C; so that two parts out of five of the semi-nocturnal arc are wanting to the opposition.

若甲点代表中天，就把成相位之星的半昼弧分成五等分，其中四份构成五分光线，在丁、乙两点都是如此；再把半夜弧也分成五等分，加上整个半昼弧之后再加三份，就构成戊、丙两点的倍五分光线；所以离对冲还差半夜弧五份中的两份。

But if the point A represents the horoscope four out of five parts of the semi-diurnal arc, makes the quintile above the earth so many of the semi-nocturnal arcs under the earth; adding the other four to both of them, make the biquintile.

但若甲点代表上升点，半昼弧五份中的四份在地平以上构成五分，半夜弧同样多份在地平以下构成五分；在两者上各再加四份，就构成倍五分。

It is to be known likewise that the quintile ray, compared to the ⚹, is greater than the ⚹ by its fifth part; for it consists of twelve parts more than the ⚹, which is the 5th part of the ⚹, or 60 parts; compared to the quadrate, it is less by five parts of the same quadrate, that is, 18°, which are the fifth part of that □, or 90; and the biquintile is greater than the △, by its fifth part, viz. 24, which are the fifth part of the trigon or 120°, but is less than the ☍ by five parts, that is, 36 of the ☍, viz. 180, or three parts out of five of the ⚹, that is, made a〔?〕 the ☍; from these it is inferred that there are two ways very easy to calculate the directions of these rays.

还要知道，五分光线与六分相比，比六分大六分的五分之一；因为它比六分多十二度，这是六分即六十度的五分之一；与四分相比，它小四分的五分之一，即十八度，这是四分即九十度的五分之一；倍五分比三分大三分的五分之一，即二十四度，这是三角即一百二十度的五分之一，但比对冲小对冲的五分之一，即三十六度，对冲为一百八十度，或说是六分的五分之三，即与对冲所差之数；由此推知，计算这些光线的推运有两种非常容易的方法。

The first is, by adding the quintile's distance to the ascension of the aspecting star, if it preceds the cardinal sign that is directed; or by substracting, if it follows; and from the sum or remainder, substracting the cardinal ascension for the remainder, is the arc of direction required.

第一种是：若成相位之星在被推运的角之前，就把五分的距离加到它的上升上；若在其后，就减去；再从和数或余数中减去该角的上升，余数就是所求的推运弧。

Let there be an example of the Quintile.

举一个五分的例子。

We have said in the above given example, the Sun's oblique ascension is 296.51, that is, to the latitude of the country; the semi-diurnal arc 64.12, the fifth part of which is 12.50; which taken from the whole semi-diurnal arc, leaves four of the five parts of that semi-diurnal arc, viz. 51.22. I add these to the Sun's oblique ascension taken in the horoscope, as it precedes it; and I make the aggregate 348.13, from which I substract the horoscope's oblique ascension, and there remains the arc of direction 38.40, viz. the quintile of Sol to the horoscope.

在上面所举的例子中，我们说过，太阳的斜升是二百九十六度五十一分，即按本地纬度所取；半昼弧六十四度十二分，其五分之一是十二度五十分；从整个半昼弧中减去它，剩下半昼弧五份中的四份，即五十一度二十二分。因为太阳在上升点之前，我就把它加到在上升点所取的太阳的斜升上，得总和三百四十八度十三分，从中减去上升点的斜升，余下推运弧三十八度四十分，即太阳的五分到上升点。

Or I substract 51.22 from the Sun's right ascension, which is 271° 5', by reason it succeeds the medium cœli, and the remainder is 219 43; from these substracting the right ascension of the medium cœli, which is 219.33, leaves the medium cœli arc of direction to the Sun's quintile 0° 10'; or I substract the quintile's secondary direction of the said distance, which is 51.22, from the Sun's primary distance from the medium cœli, which is 51.32, and there remains the same arc of direction.

或者，因为太阳在中天之后，我从太阳的赤经二百七十一度五分中减去五十一度二十二分，余数是二百一十九度四十三分；从中减去中天的赤经二百一十九度三十三分，余下中天向太阳五分的推运弧零度十分；或者，从太阳离中天的初距五十一度三十二分中，减去上述距离的五分次距五十一度二十二分，余下同一个推运弧。

Of the biquintile, care must be taken, that if we want to substract the distance of this ray, which consists of eight parts out of ten of the whole diurnal or nocturnal arc, when to the rays we direct either to the medium or imum cœli; instead of these five parts, we must take the whole semi-diurnal or nocturnal arc of the aspecting star of the other hemisphere; the other three of the same hemisphere in which the star remains; but of the biquintile, let us reject this method. The easier way, which also serves for all these rays, whenever the significators, as we call them, are found out of the cardinal signs, is this:

关于倍五分，要注意：这种光线由整个昼弧或夜弧十份中的八份构成，若我们把光线推向中天或天底，想减去这光线的距离，就不能取那五份，而必须取成相位之星在另一半球的整个半昼弧或半夜弧，再取它所在同一半球的另外三份；但对于倍五分，我们不用这个方法。更容易的方法，对所有这些光线都适用，只要征象星——我们这样称呼——位于四角以外，就是这样：

When you have found the direction, either to sextile, quartile, or opposition from the pole, adding or substracting the proportional parts, by which the quintile, sesqui-quadrate, and biquintile, are greater or less than the other ray, we shall obtain the arc of direction; for if you have the arc of direction to the ⚹, and want the same to the quintile, add to the quintile, if it be subsequent, or substract if it precedes the fifth part of the sextile from its arc of direction, and the remainder or aggregate is the arc of direction required.

当你已从极高求得向六分、四分或对冲的推运之后，加上或减去五分、倍半四分与倍五分比另一种光线大或小的那个比例部分，就得推运弧；因为若你已有向六分的推运弧，想求向五分的，就在五分在后时加上、在前时减去六分的五分之一，从六分的推运弧中加减，余数或和数就是所求的推运弧。

But remember, the ⚹ consists of the diurnal horary times, four times computed, if the aspecting star be above the earth; of the nocturnal, if below. Or if you have the direction to the quintile, for the quintile add, if it succeed; or substract, if the quintile precede the fifth part of the quadrate, from that quartile's arc of direction.

但要记住，若成相位之星在地平以上，六分由四个昼时量构成；若在地平以下，由夜时量构成。或者，若你已有向五分的推运，为求五分，若五分在后就加上，若五分在前就减去四分的五分之一，从那四分的推运弧中加减。

If you have the direction to the trine, and want that of the sesqui-quadrate, add, if this follows, or substract, if it precedes the horary times of the aspecting star, whereby the sesqui-quadrate is greater than the trine. When I say horary times, understand diurnal, if the aspecting star be above the earth, &c.

若你已有向三分的推运，想求倍半四分的，就在倍半四分在后时加上、在前时减去成相位之星的时量，倍半四分正比三分大这么多。我说时量，若成相位之星在地平以上，指昼时量，等等。

If you require the direction's arc to the biquintile, and have already the arc of direction to the trine, multiply four times the diurnal horary times of the aspecting star, if it be above the earth; the nocturnal, if under the earth; and from the product, take two of the five parts, which add, if the biquintile succeeds the trine; but if it precedes, substract from the trine's arc of direction, and the remainder or sum is the arc of direction to the biquintile; but if you have the direction's arc to the opposition, take two of the five parts of the star's semi-diurnal arc, if it is above the earth; or seminocturnal, if below; and if the biquintile succeeds the opposition, add to the same direction's arc; but if it precedes, substract these two parts, and the remainder, or sum, is the arc of direction to the biquintile.

若你要求向倍五分的推运弧，而已有向三分的推运弧，就把成相位之星的昼时量乘以四（若它在地平以上；在地平以下则用夜时量），从乘积中取五份中的两份；若倍五分在三分之后，就加上；若在前，就从三分的推运弧中减去，余数或和数就是向倍五分的推运弧；但若你已有向对冲的推运弧，就取星的半昼弧（若它在地平以上；在地平以下则取半夜弧）五份中的两份；若倍五分在对冲之后，就加到同一推运弧上；若在前，就减去这两份，余数或和数就是向倍五分的推运弧。

As in the example of the former Canon, the arc of direction of the medium cœli to the Sun's sextile is 8.44, the Sun's horary times, as being above the Earth diurnal, are 10.44; four times computed make the sextile's quantity 42.48, whose fifth part is 8.34; I therefore take 8.34 from the sextile's arc of direction, instead of the quintile to the medium cœli, because it precedes the sextile, and there remains the arc of direction to the Sun's quintile 0° 10'.

如上一则的例子，中天向太阳六分的推运弧是八度四十四分，太阳的时量因在地平以上而是昼时量，为十度四十四分；乘以四得六分的量四十二度四十八分，其五分之一是八度三十四分；因为五分在六分之前，我就从六分的推运弧中减去八度三十四分，以代替中天向五分的，余下向太阳五分的推运弧零度十分。

The direction of the imum cœli to the Sun's sesqui-quadrate, as it follows the trine, is had by adding the Sun's diurnal horary times 10.42, to the arc of direction of the medium cœli to its ⚹, which is the △ to the imum cœli, and the arc of direction becomes 19.26, as above.

天底向太阳倍半四分的推运，因倍半四分在三分之后，可把太阳的昼时量十度四十二分，加到中天向太阳六分的推运弧上而得，中天的六分就是天底的三分，推运弧成为十九度二十六分，同上。

Of the imum cœli, to the Sun's biquintile, by adding, as it succeeds the △, two of the fifth part of the Sun's diurnal ⚹, because it is above the Earth, which, as we have said, is 42.48, whose fifth part 8.34, doubled, makes 17.8; wherefore the arc of direction becomes 25.52.

天底向太阳的倍五分：因为它在三分之后，就加上太阳昼六分的五分之二，因太阳在地平以上；如前所说，昼六分是四十二度四十八分，其五分之一八度三十四分，加倍得十七度八分；所以推运弧成为二十五度五十二分。

Another way.—The directions of the medium cœli to the Sun, or if the imum cœli to the Sun's ☍, is 51.32, from this I substract, as the biquintile precedes three parts out of five of the ⚹ of the Sun's diurnal arc, that is, 25.40, and there remains the arc of direction 25.52, as above.

另一法。——中天向太阳，或天底向太阳对冲的推运弧，是五十一度三十二分；因为倍五分在前，我从中减去太阳昼弧六分的五分之三，即二十五度四十分，余下推运弧二十五度五十二分，同上。

The direction of the horoscope to the Sun's quintile is thus obtained:

上升点向太阳五分的推运是这样求得的：

We have already, in the former Canon, calculated the Sun's sextile to the horoscope, which was 30.6; to this I add, as the quintile succeeds the sextile, the fifth part of the Sun's sextile ray, which is 8.34, and I make the houses arc of direction to the quintile of the Sun 33.40.

我们在上一则中已算出太阳的六分到上升点，是三十度六分；因为五分在六分之后，我就加上太阳六分光线的五分之一，即八度三十四分，得诸宫向太阳五分的推运弧三十三度四十分。

Another Method.—The Sun's semi-diurnal arc, which is the quadrate to the houses, is 64.12. that is, of the distance, not of direction, its fifth part is 12.50, which are the Sun's secondary distance from the medium cœli, the primary is 51.32; from which, substracting that secondary one, leaves the arc of direction, 38.42, greater than the former by two, by reason of the fractions that are to be met with in the different calculations.

另一方法。——太阳的半昼弧，即对诸宫的四分，是六十四度十二分，这是距离，不是推运弧；其五分之一十二度五十分，就是太阳离中天的次距，初距是五十一度三十二分；从中减去那个次距，余下推运弧三十八度四十二分，比前一个大二分，这是由于不同计算中遇到的零数之故。

We have said that the horoscope direction to the Sun's trine, was 72.56; to this I add the Sun's horary times, 10.42, and I make the horoscope arc of directions, to the Sun's sesqui-quadrate, 83.38; or I add the Sun's semi-diurnal arc, 64.12, of the arc of direction of the imum cœli, to the Sun's sesqui-quadrate, which was, as we have said, 19.26, and the same produces the arc of direction, 83.38.

我们说过，上升点向太阳三分的推运弧是七十二度五十六分；我在其上加太阳的时量十度四十二分，得上升点向太阳倍半四分的推运弧八十三度三十八分；或者，把太阳的半昼弧六十四度十二分，加到天底向太阳倍半四分的推运弧上，如我们所说是十九度二十六分，得出同一推运弧八十三度三十八分。

And it is the same in all of them; so that by addition and substraction only, the direction of those rays may be calculated with the greatest exactness. But if any one would provide himself with a Ptolemaic Astrobate, with the horary circles, crepuscules, the Zodiac's latitude, and all other things requisite, it would be of very great service towards foreseeing the aspects, before the calculation, both of this and the following Canons.

一切都是如此；所以只用加减，就能以最大的精确算出这些光线的推运。但若有人备一具托勒密式的星盘仪，带有时圈、晨昏蒙影、黄道的纬度及其他一切所需之物，在计算之前预见这些相位，对本则与以下各则都大有帮助。