PART I.
HERE BIGINNETH THE DESCRIPCION OF THE ASTROLABIE.
1. Thyn Astrolabie hath a ring to putten on the thoumbe of thy right hand in taking the heighte of thinges. And tak keep, for from hennes-forthward, I wol clepe the heighte of any thing that is taken by thy rewle, the altitude, with-oute mo wordes.
2. This ring renneth in a maner turet, fast to the moder of thyn Astrolabie, in so rowm a space that hit desturbeth nat the instrument to hangen after his righte centre.
3. The Moder of thyn Astrolabie is the thikkeste plate, perced with a large hole, that resseyveth in hir wombe the thinne plates compowned for diverse clymatz, and thy riet shapen in manere of a net or of a webbe of a loppe; and for the more declaracioun, lo here the figure. 5
4. This moder is devyded on the bak-half with a lyne, that cometh dessendinge fro the ring down to the nethereste bordure. The whiche lyne, fro the for-seide ring un-to the centre of the large hole amidde, is cleped the south lyne, or elles the lyne meridional. And the remenant of this lyne downe to the bordure 5 is cleped the north lyne, or elles the lyne of midnight. And for the more declaracioun, lo here the figure.
5. Over-thwart this for-seide longe lyne, ther crosseth him another lyne of the same lengthe from est to west. Of the whiche lyne, from a litel croys + in the bordure un-to the centre of the large hole, is cleped the Est lyne, or elles the lyne Orientale; and the remenant of this lyne fro the forseide + un-to the bordure, 5 is cleped the West lyne, or the lyne Occidentale. Now hastow here the foure quarters of thin Astrolabie, devyded after the foure principals plages or quarters of the firmament. And for the more declaracioun, lo here thy figure.
6. The est side of thyn Astrolabie is cleped the right side, and the west side is cleped the left side. Forget nat this, litel Lowis. Put the ring of thyn Astrolabie upon the thoumbe of thy right hand, and thanne wole his right syde be toward thy left syde, and his left syde wol be toward thy right syde; tak this rewle general, 5 as wel on the bak as on the wombe-side. Upon the ende of this est lyne, as I first seide, is marked a litel +, wher-as evere-mo generaly is considered the entring of the first degree in which the sonne aryseth. And for the more declaracioun, lo here the figure. 10
7. Fro this litel + up to the ende of the lyne meridional, under the ring, shaltow finden the bordure devyded with 90 degrees; and by that same proporcioun is every quarter of thin Astrolabie devyded. Over the whiche degrees ther ben noumbres of augrim, that devyden thilke same degrees fro fyve to fyve, as sheweth by 5 longe strykes by-twene. Of whiche longe strykes the space by-twene contienith a mile-wey. And every degree of the bordure contieneth foure minutes, that is to seyn, minutes of an houre. And for more declaracioun, lo here the figure.
8. Under the compas of thilke degrees ben writen the names of the Twelve Signes, as Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricornus, Aquarius, Pisces; and the nombres of the degrees of tho signes ben writen in augrim above, and with longe devisiouns, fro fyve to fyve; devyded fro 5 tyme that the signe entreth un-to the laste ende. But understond wel, that thise degrees of signes ben everich of hem considered of 60 minutes, and every minute of 60 secondes, and so forth in-to smale fraccions infinit, as seith Alkabucius. And ther-for, know wel, that a degree of the bordure contieneth foure 10 minutes, and a degree of a signe contieneth 60 minutes, and have this in minde. And for the more declaracioun, lo here thy figure.
9. Next this folweth the Cercle of the Dayes, that ben figured in maner of degrees, that contienen in noumbre 365; divyded also with longe strykes fro fyve to fyve, and the nombres in augrim writen under that cercle. And for more declaracioun, lo here thy figure.
10. Next the Cercle of the Dayes, folweth the Cercle of the names of the Monthes; that is to seyen, Ianuare, Februare, Marcius, Aprile, Mayus, Iuin, Iulius, Augustus, Septembre, October, Novembre, Decembre. The names of thise monthes were cleped in Arabiens, somme for hir propretees, and some by 5 statutz of lordes, some by other lordes of Rome. Eek of thise monthes, as lyked to Iulius Cesar and to Cesar Augustus, some were compowned of diverse nombres of dayes, as Iuil and August. Thanne hath Ianuare 31 dayes, Februare 28, March 31, Aprille 30, May 31, Iunius 30, Iulius 31, Augustus 31, 10 September 30, Octobre 31, Novembre 30, December 31. Natheles, al-though that Iulius Cesar took 2 dayes out of Feverer and put hem in his moneth of Iuille, and Augustus Cesar cleped the moneth of August after his name, and ordeyned it of 31 dayes, yit truste wel, that the sonne dwelleth ther-for nevere the more ne 15 lesse in oon signe than in another.
11. Than folwen the names of the Halidayes in the Kalender, and next hem the lettres of the Abc. on which they fallen. And for the more declaracioun, lo here thy figure.
12. Next the forseide Cercle of the Abc., under the cros-lyne, is marked the scale, in maner of two squyres, or elles in manere of laddres, that serveth by hise 12 poyntes and his devisiouns of ful many a subtil conclusioun. Of this forseide scale, fro the croos-lyne un-to the verre angle, is cleped _umbra versa_, and the 5 nether partie is cleped the _umbra recta_, or elles _umbra extensa_. And for the more declaracioun, lo here the figure.
13. Thanne hastow a brood Rewle, that hath on either ende a square plate perced with a certein holes, some more and some lesse, to resseyven the stremes of the sonne by day, and eek by mediacioun of thyn eye, to knowe the altitude of sterres by nighte. And for the more declaracioun, lo here thy figure. 5
14. Thanne is ther a large Pyn, in maner of an extree, that goth thorow the hole that halt the tables of the clymates and the riet in the wombe of the Moder, thorw which Pyn ther goth a litel wegge which that is cleped 'the hors,' that streyneth alle thise parties to-hepe; this forseide grete Pyn, in maner of an 5 extree, is imagined to be the Pol Artik in thyn Astrolabie. And for the more declaracioun, lo here the figure.
15. The wombe-side of thyn Astrolabie is also devyded with a longe croys in foure quarters from est to west, fro south to north, fro right syde to left syde, as is the bak-syde. And for the more declaracioun, lo here thy figure.
16. The bordure of which wombe-side is devyded fro the poynt of the est lyne un-to the poynt of the south lyne under the ring, in 90 degres; and by that same proporcioun is every quarter devyded as is the bak-syde, that amonteth 360 degrees. And understond wel, that degrees of this bordure ben answering and 5 consentrik to the degrees of the Equinoxial, that is devyded in the same nombre as every othere cercle is in the heye hevene. This same bordure is devyded also with 23 lettres capitals and a smal croys + above the south lyne, that sheweth the 24 houres equals of the clokke; and, as I have said, 5 of thise degrees 10 maken a mile-wey, and 3 mile-wey maken an houre. And every degree of this bordure conteneth 4 minutes, and every minut 60 secoundes; now have I told thee twye. And for the more declaracioun, lo here the figure.
17. The plate under thy riet is descryved with 3 principal cercles; of which the leste is cleped the cercle of Cancer, by-cause that the heved of Cancer turneth evermor consentrik up-on the same cercle. In this heved of Cancer is the grettest declinacioun northward of the sonne. And ther-for is he cleped the 5 Solsticioun of Somer; whiche declinacioun, aftur Ptholome, is 23 degrees and 50 minutes, as wel in Cancer as in Capricorne. This signe of Cancre is cleped the Tropik of Somer, of _tropos_, that is to seyn 'agaynward'; for thanne by-ginneth the sonne to passe fro us-ward. And for the more declaracioun, lo here the figure. 10 The middel cercle in wydnesse, of thise 3, is cleped the Cercle Equinoxial; up-on whiche turneth evermo the hedes of Aries and Libra. And understond wel, that evermo this Cercle Equinoxial turneth iustly fro verrey est to verrey west; as I have shewed thee in the spere solide. This same cercle is cleped also the Weyere, 15 _equator_, of the day; for whan the sonne is in the hevedes of Aries and Libra, than ben the dayes and the nightes ilyke of lengthe in al the world. And ther-fore ben thise two signes called the Equinoxies. And alle that moeveth with-in the hevedes of thise Aries and Libra, his moeving is cleped northward; and alle that moeveth with-oute thise hevedes, his moeving is cleped south-ward as fro the equinoxial. Tak keep of thise latitudes north and sowth, and forget it nat. By this Cercle Equinoxial ben considered the 24 houres of the clokke; for everemo the arysing of 15 degrees of the equinoxial maketh an 25 houre equal of the clokke. This equinoxial is cleped the girdel of the firste moeving, or elles of the _angulus primi motus vel primi mobilis_. And _nota_, that firste moeving is cleped 'moeving' of the firste moevable of the 8 spere, whiche moeving is fro est to west, and eft agayn in-to est; also it is clepid 'girdel' of the first 30 moeving, for it departeth the firste moevable, that is to seyn, the spere, in two ilyke parties, evene-distantz fro the poles of this world.
The wydeste of thise three principal cercles is cleped the Cercle of Capricorne, by-cause that the heved of Capricorne 35 turneth evermo consentrik up-on the same cercle. In the heved of this for-seide Capricorne is the grettest declinacioun southward of the sonne, and ther-for is it cleped the Solsticioun of Winter. This signe of Capricorne is also cleped the Tropik of Winter, for thanne byginneth the sonne to come agayn to us-ward. And for 40 the more declaracioun, lo here thy figure.
18. Upon this forseide plate ben compassed certein cercles that highten Almicanteras, of which som of hem semen perfit cercles, and somme semen inperfit. The centre that standith a-middes the narwest cercle is cleped the Senith; and the netherest cercle, or the firste cercle, is clepid the Orisonte, that 5 is to seyn, the cercle that devydeth the two emisperies, that is, the partie of the hevene a-bove the erthe and the partie be-nethe. Thise Almicanteras ben compowned by two and two, al-be-it so that on divers Astrolabies some Almicanteras ben devyded by oon, and some by two, and somme by three, after the quantite of the 10 Astrolabie. This forseide senith is imagened to ben the verrey point over the crowne of thyn heved; and also this senith is the verrey pool of the orisonte in every regioun. And for the more declaracioun, lo here thy figure.
19. From this senith, as it semeth, ther come a maner crokede strykes lyke to the clawes of a loppe, or elles like to the werk of a womanes calle, in kerving overthwart the Almikanteras. And thise same strykes or divisiouns ben cleped Azimuthz. And they devyden the orisonte of thyn Astrolabie in four and twenty 5 devisiouns. And thise Azimutz serven to knowe the costes of the firmament, and to othre conclusiouns, as for to knowe the cenith of the sonne and of every sterre. And for more declaracioun, lo here thy figure.
20. Next thise azimutz, under the Cercle of Cancer, ben ther twelve devisiouns embelif, moche like to the shap of the azimutes, that shewen the spaces of the houres of planetes; and for more declaracioun, lo here thy figure.
21. The Riet of thyn Astrolabie with thy zodiak, shapen in maner of a net or of a loppe-webbe after the olde descripcioun, which thow mayst tornen up and doun as thy-self lyketh, conteneth certein nombre of sterres fixes, with hir longitudes and latitudes determinat; yif so be that the makere have nat erred. The names 5 of the sterres ben writen in the margin of the riet ther as they sitte; of whiche sterres the smale poynt is cleped the Centre. And understond also that alle sterres sittinge with-in the zodiak of thyn Astrolabie ben cleped 'sterres of the north,' for they arysen by northe the est lyne. And alle the remenant fixed, out of the 10 zodiak, ben cleped 'sterres of the south;' but I sey nat that they arysen alle by southe the est lyne; witnesse on Aldeberan and Algomeysa. Generally understond this rewle, that thilke sterres that ben cleped sterres of the north arysen rather than the degree of hir longitude, and alle the sterres of the south arysen after the 15 degree of hir longitude; this is to seyn, sterres fixed in thyn Astrolabie. The mesure of this longitude of sterres is taken in the lyne ecliptik of hevene, under which lyne, whan that the sonne and the mone ben lyne-right or elles in the superfice of this lyne, than is the eclips of the sonne or of the mone; as I shal declare, 20 and eek the cause why. But sothly the Ecliptik Lyne of thy zodiak is the outtereste bordure of thy zodiak, ther the degrees ben marked.
Thy Zodiak of thyn Astrolabie is shapen as a compas which that conteneth a large brede, as after the quantite of thyn Astrolabie; 25 in ensample that the zodiak in hevene is imagened to ben a superfice contening a latitude of twelve degrees, wheras al the remenant of cercles in the hevene ben imagined verrey lynes with-oute eny latitude. Amiddes this celestial zodiak ys imagined a lyne, which that is cleped the Ecliptik Lyne, under which lyne is evermo the 30 wey of the sonne. Thus ben ther six degrees of the zodiak on that on side of the lyne, and six degrees on that other. This zodiak is devided in twelve principal devisiouns, that departen the twelve signes. And, for the streitnes of thin Astrolabie, than is every smal devisioun in a signe departid by two degrees and two; 35 I mene degrees contening sixty minutes. And this forseide hevenissh zodiak is cleped the Cercle of the Signes, or the Cercle of the Bestes; for _zodia_ in langage of Greek sowneth 'bestes' in Latin tonge; and in the zodiak ben the twelve signes that ban names of bestes; or elles, for whan the sonne entreth in any of the 40 signes, he taketh the propretee of swich bestes; or elles, for that the sterres that ben there fixed ben disposed in signes of bestes, or shape like bestes; or elles, whan the planetes ben under thilke signes, they causen us by hir influence operaciouns and effectes lyk to the operaciouns of bestes. And understonde also, that whan 45 an hot planete cometh in-to an hot signe, than encresseth his hete; and yif a planete be cold, thanne amenuseth his coldnesse, by-cause of the hote signe. And by this conclusioun maystow take ensample in alle the signes, be they moist or drye, or moeble or fix; rekening the qualitee of the planete as I first seide. And everich of 50 thise twelve signes hath respecte to a certein parcelle of the body of a man and hath it in governance; as Aries hath thyn heved, and Taurus thy nekke and thy throte, Gemini thyn armholes and thyn armes, and so forth; as shal be shewed more pleyn in the fifte partie of this tretis. This zodiak, which that is part of the eighte 55 spere, over-kerveth the equinoxial; and he over-kerveth him again in evene parties; and that on half declineth southward, and that other northward, as pleynly declareth the tretis of the spere. And for more declaracioun, lo here thy figure.
22. Thanne hastow a label, that is schapen lyk a rewle, save that it is streit and hath no plates on either ende with holes; but, with the smale point of the forseide label, shallow calcule thyne equaciouns in the bordure of thin Astrolabie, as by thyn almury. And for the more declaracioun, lo here thy figure. 5
23. Thyn Almury is cleped the Denticle of Capricorne, or elles the Calculer. This same Almury sit fix in the bed of Capricorne, and it serveth of many a necessarie conclusioun in equaciouns of thinges, as shal be shewed; and for the more declaracioun, lo here thy figure. 5
HERE ENDETH THE DESCRIPCION OF THE ASTROLABIE.