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parties, wole I shewe thee under ful lighte rewles and naked 20 wordes in English; for Latin ne canstow yit but smal, my lyte sone. But natheles, suffyse to thee thise trewe conclusiouns in English, as wel as suffyseth to thise noble clerkes Grekes thise same conclusiouns in Greek, and to Arabiens in Arabik, and to Iewes in Ebrew, and to the Latin folk in Latin; whiche Latin folk han hem 25 furst out of othre diverse langages, and writen in hir owne tonge, that is to sein, in Latin. And god wot, that in alle thise langages, and in many mo, han thise conclusiouns ben suffisantly lerned and taught, and yit by diverse rewles, right as diverse pathes leden diverse folk the righte wey to Rome. Now wol I prey meekly 3o every discret persone that redeth or hereth this litel tretis, to have my rewde endyting for excused, and my superfluite of wordes, for two causes. The firste cause is, for that curious endyting and hard sentence is ful hevy atones for swich a child to lerne. And the seconde cause is this, that sothly me semeth betre to wryten un-to 35 a child twyes a good sentence, than he forgete it ones. And Lowis, yif so be that I shewe thee in my lighte English as trewe conclusiouns touching this matere, and naught only as trewe but as many and as subtil conclusiouns as ben shewed in Latin in any commune tretis of the Astrolabie, con me the more thank; and 40 preye god save the king, that is lord of this langage, and alle that him feyth bereth and obeyeth, everech in his degree, the more and the lasse. But considere wel, that I ne usurpe nat to have founde this werk of my labour or of myn engin. I nam but a lewd compilatour of the labour of olde Astrologiens, and have hit translated 45 in myn English only for thy doctrine; and with this swerd shal I sleen envye. I. The firste partie of this tretis shal reherse the figures and the membres of thyn Astrolabie, bi-cause that thou shalt han the grettre knowing of thyn owne instrument.
parts, I write for thee in English, just as Greeks, Arabians, Jews, and Romans were accustomed to write such things in their own tongue. I pray all to excuse my shortcomings ; and thou, Lewis, shouldst thank me if I teach thee as much in English as most common treatises can do in Latin. I have done no more than compile from old writers on the subject, and I have translated it into English solely for thine instruction; and with this sword shall I slay envy. The first part gives a description of the instrument itself.
II. The second partie shal teche thee werken the verrey 50
of oure doctours, in which thou maist lerne a gret part of the
The second teaches the practical working of it.
The third shall contain tables of latitudes and longitudes of fixed
The fourth shall shew the motions of the heavenly bodies, and
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, 5 lo here the figure. 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 5 meridional. And the remenant of this lyne downe to the bordure is cleped the north lyne, or elles the lyne of midnight. And for the more declaracioun, lo here the figure.
Here begins the first part; i.e. the description of the Astrolabe itself. 1. The Ring. See figs. I and 2. The Latin name is Armilla suspensoria ; the Arabic name is spelt al/tahuacia in MS. Camb. Univ. Ii. 3. 3, but Stöffler says it is Alanthica, Alphantia, or Aðalhantica. For the meaning of ‘rewle, see § 13. 2. The Turet. This answers nearly to what we call an eye or a swivel. The metal plate, or loop, to which it is fastened, or in which it turns, is called in Latin Ansa or Armilla Reflexa, in Arabic Alhabos. 3. The Moder. In Latin, Mater or Rotula. This forms the body of the instrument, the back of which is shewn in fig. 1, the front in fig. 2. The ‘large hole' is the wide depression sunk in the front of it, into which the various discs are dropped. In the figure, the ‘Rete' is shewn fitted into it. 4. See fig. I ; Chaucer describes the ‘bak-half” of the instrument first. The centre of the ‘large hole amydde’ is the centre of the instrument, where a smaller hole is pierced completely through. The Southe lyne (marked Meridies in figs. I and 2) is also called Linea Meridiei, the North lyne is also named Linea Media Noctis.
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, 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. lo 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 longe strykes by-twene. Of whiche longe strykes the space bytwene 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,
5. The Est lyne is marked with the word Oriens; the West lyne, with Occidens. 6. The rule is the same as in heraldry, the right or dexter side being towards the spectator's left. 7. As the 360 degrees answer to 24 hours of time, 15° answer to an hour, and 5° to twenty minutes, or a Mile-way, as it is the average time for walking a mile. So also 1° answers to 4 minutes of time. See the two outermost circles in fig. 1, and the divisions of the “border’ in fig. 2. 8. See the third and fourth circles (reckoning inwards) in fig. I.
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 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 6o secondes, and so forth in-to smale fraccions infinit, as seith Alkabucius. And 1o ther-for, know wel, that a degree of the bordure contieneth foure 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 5 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 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 10 31, Aprille 30, May 31, Iunius 3o, Iulius 31, Augustus 31, 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,
9. See the fifth and sixth circles in fig. 1.
10. See the seventh, eighth, and ninth circles in fig. 1. The names of the months are all Roman. The month formerly called Quinctilis was first called Julius in B. C. 44; that called Sextilis was named Augustus in B. C. 27. It is a nuistake to say that Julius and Augustus made the alterations spoken of in the text; what Julius Caesar really did, was to add 2 days to the months of January, August (Sextilis), and December, and I day to April, June, September, and November. February never had more than 28 days till he introduced bissextile years.