Imatges de pàgina

ascensioun up-on the est orisonte, and waite wher thyn almury toucheth the bordure, and set ther a prikke. Turne thanne thy riet upward til that the ende of the same signe sitte up-on the est orisonte, and waite eft-sones wher as thyn almury toucheth the 5 bordure, and set ther a-nother prikke. Rikne thanne the noumbre of degrees in the bordure by-twixe bothe prikkes, and tak ther the assencioun of the signe in the embelif cercle. And understond wel, that alle signes in thy zodiak, fro the heved of Aries unto the ende of Virgo, ben cleped signes of the north fro the equinoxial ; 10 and these signes arysen by-twixe the verrey est and the verrey north in oure orisonte generaly for evere. And alle signes fro the heved of Libra un-to the ende of Pisces ben cleped signes of the south fro the equinoxial ; and thise signes arysen ever-mo by-twixe the verrey est and the verrey south in oure orisonte. Also every 15 signe by-twixe the heved of Capricorne un-to the ende of Geminis aryseth on oure orisonte in lasse than two houres equales; and thise same signes, fro the heved of Capricorne un-to the ende of Geminis, ben cleped ‘tortuos signes’ or ‘croked signes,’ for they arisen embelif on oure orisonte; and thise crokede signes 20 ben obedient to the signes that ben of right assencioun. The signes of right assencioun ben fro the heved of Cancer to the ende of Sagittare; and thise signes arysen more upright, and they ben called eke sovereyn signes; and everich of hem aryseth in more space than in two houres. Of which signes, Gemini obeyeth 25 to Cancer; and Taurus to Leo ; Aries to Virgo; Pisces to Libra; Aquarius to Scorpioun ; and Capricorne to Sagittare. And thus

on as large a scale as is convenient. It is done by observing where the ends of the given sign, estimated along the outer rim of the zodiacal circle in fig. 2, cross the horizon obliquus as the rete is turned about. Thus, the beginning of Aries lies on the horizon obliquus, and as the rete revolves to the right, the end of it, on the outer rim, will at last lie exactly on the same curved line. When this is the case, the rete ought to have moved through an angle of about 14°, as explained in § 26. By far the best way is to tabulate the results once for all, as I have there done. It is readily seen, from fig. 2, that the signs from Aries to Virgo are northern, and from Libra to Pisces are southern signs. The signs from Capricorn to Gemini are the oblique signs, or as Chaucer calls them, ‘tortuous,” and ascend in less than 2 hours; whilst the direct signs, from Cancer to Sagittarius, take more than 2 hours to ascend; as shewn in the table on p. 209. The eastern signs in fig. 2 are said to obey to the corresponding western ones.

ever-mo two signes, that ben y-lyke fer fro the heved of Capricorne, obeyen everich of hem til other. And for more declaracioun, lo 3o here the figure.

29. To knowe iustly the foure quarters of the world, as est, west, north, and sowth.

[Ad cognoscendum evidenter quatuor partes mundi, scilicet, orientem, austrum, aquilonem, et occidentem.]

Take the altitude of thy sonne whan thee list, and note wel the quarter of the world in which the sonne is for the tyme by the azimutz. Turne thanne thyn Astrolabie, and set the degree of the sonne in the almikanteras of his altitude, on thilke side that 5 the sonne stant, as is the manere in taking of houres; and ley thy label on the degree of the sonne, and rikene how many degrees of the bordure ben by-twixe the lyne meridional and the point of thy label; and note wel that noumbre. Turne thanne a-gayn thyn Astrolabie, and set the point of thy gret rewle, ther thou takest Io thyne altitudes, up-on as many degrees in his bordure fro his meridional as was the point of thy label fro the lyne meridional on the wombe-syde. Tak thanne thyn Astrolabie with bothe handes sadly and slely, and lat the sonne shyne thorow bothe holes of thy rewle; and sleyly, in thilke shyninge, lat thyn Astrolabie couch 15 adoun evene up-on a smothe grond, and thanne wol the verrey lyne meridional of thyn Astrolabie lye evene south, and the est lyne wole lye est, and the west lyne west, and north lyne north, so that thou werke softly and avisely in the couching; and thus hastow the 4 quarters of the firmament. And for the more ao declaracioun, lo here the figure.

29. Here both sides of the Astrolabe are used, the ‘rewle' being made to revolve at the back, and the “label’ in front, as usual. First, by the back of the instrument and the ‘rewle, take the sun's altitude. Turn the Astrolabe round, and set the sun's degree at the right altitude among the almicanteras, and then observe, by help of the label, how far the sun is from the meridian. Again turn the instrument round, and set the ‘rewle' as far from the meridian as the label was. Then, holding the instrument as near the ground and as horizontal as possible, let the sun shine through the holes of the ‘rewle,’ and immediately after lay the Astrolabe down, without altering the azimuthal direction of the meridional line. It is clear that this line will then point southwards, and the other points of the compass will also be known.

30. To knowe the altitude of planetes fro the wey of the sonne, whether so they be north or south fro the forseide wey.

[Ad cognoscendum altitudinem planetarum a cursu solis, utrum sint in parte australi vel boreali a cursu supra dicto.]

Lok whan that a planete is in the lyne meridional, yif that hir altitude be of the same heyghte that is the degree of the sonne for that day, and than is the planete in the verrey wey of the sonne, and hath no latitude. And yif the altitude of the planete be heyere than the degree of the sonne, than is the planete north fro 5 the wey of the sonne swich a quantite of latitude as sheweth by thyn almikanteras. And yif the altitude of the planete be lasse than the degree of the sonne, thanne is the planete south fro the wey of the sonne swich a quantite of latitude as sheweth by thyn almikanteras. This is to seyn, fro the wey wher-as the sonne wente thilke day, but nat from the wey of the sonne in every place of the zodiak. And for the more declaracioun, lo here the figure.


31. To knowe the semith of the arysing of the sonne, this is to seyn, the partie of the orisonte in which that the sonne aryseth.

[Ad cognoscendum signum de ortu solis, scilicet, illam partem orientis in qua oritur sol.]

Thou most first considere that the sonne aryseth nat al-wey verrey est, but some tyme by north the est, and som tyme by southe the est. Sothly, the sonne aryseth never-mo verrey est in oure

30. This turns upon the definition of the phrase “the wey of the sonne.’ It does not mean the zodiacal circle, but the sun's apparent path on a given day of the year. The sun's altitude changes but little in one day, and is supposed here to remain the same throughout the time that he is, on that day, visible. Thus, if the sun's altitude be 613%, the way of the sun is a small circle, viz. the tropic of Cancer. If the planet be then on the zodiac, in the 1st degree of Capricorn, it is 47° S. from the way of the sun, and so on.

31. The word ‘senith’ is here used in a peculiar sense; it does not mean, as it should, the genith point, or point directly overhead, but is made to imply the point on the horizon, (either falling upon an

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orisonte, but he be in the heved of Aries or Libra. Now is thyn 5 orisonte departed in 24 parties by thy azimutz, in significacion of 24 partiez of the world; al-be-it so that shipmen rikne thilke partiez in 32. Thanne is ther no more but waite in which azimut that thy sonne entreth at his arysing; and take ther the senith of the arysing of the sonne. The manere of the devisioun of thyn 10 Astrolabie is this; I mene, as in this cas. First is it devided in 4 plages principalx with the lyne that goth from est to west, and than with a-nother lyne that goth fro south to north. Than is it devided in smale partiez of azimutz, as est, and est by southe, whereas is the firste azimut above the est lyne ; and so forth, fro 15 partie to partie, til that thou come agayn un-to the est lyne. Thus maistow understond also the senith of any sterre, in which partie he ryseth, &c. And for the more declaracion, lo here the figure.

32. To knowe in which partie of the firmament is the coniunccioun.

[Ad cognoscendum in qua parte firmamenti sunt
coniuncciones solis et lune.]

Considere the tyme of the coniunccion by thy kalender, as thus; lok how many houres thilke coniunccion is fro the midday of the day precedent, as sheweth by the canoun of thy kalender. Rikne thanne thilke nombre of houres in the bordure of thyn Astrolabie,

azimuthal line, or lying between two azimuths), which denotes the point of sunrise. In the Latin rubric, it is called signum. This point is found by actual observation of the sun at the time of rising. Chaucer's azimuths divide the horizon into 24 parts; but it is interesting to observe his remark, that ‘shipmen’ divide the horizon into 32 parts, exactly as a compass is divided now-a-days. The reason for the division into 32 parts is obviously because this is the easiest way of reckoning the direction of the wind. For this purpose, the horizon is first divided into 4 parts; each of these is halved, and each half-part is halved again. It is easy to observe if the wind lies halfway between S. and E., or half-way between S. and S.E., or again half-way between S. and S.S.E.; but the division into 24 parts would be unsuitable, because third-parts are much more difficult to estimate.

32. The Latin rubric interprets the conjunction to mean that of the sun and moon. The time of this conjunction is to be ascertained from a calendar. If, e.g. the calendar indicates 9 A.M. as the time of conjunction on the 12th day of March, when the sun is in the first point of as thou art wont to do in knowing of the houres of the day or of 5 the night; and ley thy label over the degree of the sonne; and thanne wol the point of thy label sitte up-on the hour of the coniunccion. Loke thanne in which azimut the degree of thy sonne sitteth, and in that partie of the firmament is the coniunccioun. And for the more declaracioun, lo here thy figure. i o

33. To knowe the senith of the altitude of the sonne, &c. [Ad cognoscendum signa de altitudine solis.]

This is no more to seyn but any tyme of the day tak the altitude of the sonne; and by the azimut in which he stondeth, maystou seen in which partie of the firmament he is. And in the same wyse maystou seen, by the night, of any sterre, whether the sterre sitte est or west or north, or any partie by-twene, after the 5 name of the azimut in which is the sterre. And for the more declaracioun, lo here the figure.

34. To knowe sothly the degree of the longitude of the mone, or of any planete that hath no latitude for the tyme fro the ecliptik lyne.

[Ad cognoscendum veraciter gradum de longitudine lune, vel alicuius planete quinon habet longitudinem protempore causante linea ecliptica.]

Tak the altitude of the mone, and rikne thyn altitude up among

Aries, as in § 3, the number of hours after the preceding midday is 21, which answers to the letter X in the border (fig. 2). Turn the rete till the first point of Aries lies under the label, which is made to point to X, and the label shews at the same moment that the degree of the sun is very nearly at the point where the equinoctial circle crosses the azimuthal circle which lies 50° to the E. of the meridian. Hence the conjunction takes place at a point of which the azimuth is 50° to the E. of the S. point, or 5° to the eastward of the S.E. point. The proposition merely amounts to finding the sun's azimuth at a given time. Fig. 11 shews the position of the rete in this case. 33. Here ‘senyth” is again used to mean azimuth, and the proposition is, to find the sun's azimuth by taking his altitude, and setting his degree at the right altitude on the almicanteras. Of course the two co-ordinates, altitude and azimuth, readily indicate the sun's exact position; and the same for any star or planet. 34. The moon's latitude is never more than 54° from the ecliptic,

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