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Here begynneth the descripcioun of thin Astralabie.
Thyn Astrolabie hath a ring to putten onthe thombe of thi right hond in taking the height of thinges. And tak kep, or from henes forthward I wol clepen the heighte of any thing that is taken by the rewle "the altitude," withoute moo wordes.
This ryng renneth in a maner toret fast to the moder of thyn Astrelabie in so rowme a space that it distourbith not the instrument to hangen after his right centre.
The moder of thin Astrelabye is thikkest plate, perced with a large hool, that resceiveth in hir wombe the thynne plates compowned for diverse clymates, and thy reet shapen in manere of a nett or of a web of a loppe.
This moder is dividid on the bakhalf with a lyne that cometh descending fro the ring doun to the netherist bordure. The whiche lyne, fro the forseide ring unto the centre of the large hool amidde, is clepid the south lyne, or ellis the lyne meridional. And the remenaunt of this lyne doun to the bordure is
Overthwart this forseide longe lyne ther crossith him another lyne of the same lengthe from eest to west. Of the whiche lyne, from a litel cros (+) in the bordure unto the centre of the large hool, is clepid the est lyne, or ellis the lyne orientale. And the remenaunt of this lyne, fro the forseide centre unto the bordure, is clepid the west lyne, or ellis the lyne occidentale. Now hast thou here the foure quarters of thin Astrolabie divided after the foure principales plages or quarters of the firmament.
The est syde of thyn Astrolabie is clepid the right syde, and the west syde is clepid the left syde. Forget not thys, litel Lowys. Put the ryng of thyn Astrolabie upon the thombe of thi right hond, and than wol his right side be toward thi lift side, and his left side wol be toward thy right side. Tak this rewle generall, as wel on the bak as on the wombe syde. Upon the ende of this est lyne, as I first seide, is marked a litel cros (+), where as evere moo generaly is considerid the entring of the first degre in which the sonne arisith.
Fro this litel cros (+) up to the ende of the lyne meridionall, under the ryng, shalt thou fynden the bordure divided with 90 degrees; and by that same proporcioun is every quarter of thin Astrolabie divided. Over the whiche degrees there ben noumbres of augrym that dividen thilke same degres fro 5 to 5, as shewith by longe strikes bitwene. Of whiche longe strikes the space bitwene contenith a myle wey, and every degre of the bordure conteneth 4 minutes; this is to seien, mynutes of an houre.
Under the compas of thilke degrees ben writen the names of the 12 Signes: as Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricornus, Aquarius, Piscis. And the nombres of the degrees of thoo signes be writen in augrym above, and with longe divisiouns fro 5 to 5, dyvidid fro the ryme that the signe entrith unto the last ende. But understond wel that these degres of signes ben everich of hem considred of 60 mynutes, and every mynute of 60 secundes, and so furth into smale fraccions infinite, as saith Alkabucius. And therfore knowe wel that a degre of the bordure contenith 4 minutes, and a degre of a signe conteneth 60 minutes, and have this in mynde.
Next this folewith the cercle of the daies, that ben figured in manere of degres, that contenen in nomhre 365, dividid also with longe strikes fro 5 to 5, and the nombre in augrym writen under that cercle.
Next the cercle of the daies folewith the cercle of the names of the monthes, that is to say, Januarius, Februarius, Marcius, Aprilis, Maius, Junius, Julius, Augustus, September, October, November, December. The names of these monthes were clepid somme for her propirtees and somme by statutes of Arabiens, somme by othre lordes of Rome. Eke of these monthes, as liked to Julius Cesar and to Cesar Augustus, somme were compouned of diverse nombres of daies, as Julie and August. Than hath Januarie 31 daies, Februarie 28, March 31, Aprill 30, May 31, Junius 30, Julius 31, Augustus 31, Septembre 30, Octobre 31, Novembre 30, Decembre 31. Natheles, all though that Julius Cesar toke 2 daies out of Feverer and putte hem in his month of Juyll, and Augustus Cesar clepid the month of August after his name and ordeined it of 31 daies, yit truste wel that the sonne dwellith therfore nevere the more ne lasse in oon signe than in another.
Than folewen the names of the holy daies in the Kalender, and next hem the lettres of the A B C on whiche thei fallen.
Next the forseide cercle of the A B C, under the cross lyne, is marked the skale in manere of 2 squyres, or ellis in manere of laddres, that serveth by his 12 pointes and his dyvisiouns of ful many a subtil conclusioun. Of this forseide skale fro the cross lyne unto the verrey angle is clepid Umbra Versa, and the nethir partie is clepid Umbra Recta, or ellis Umbra Extensa.
Than hast thou a brod reule, that hath on either ende a square plate perced with certein holes, somme more and somme lasse, to resceyve the stremes of the sonne by day, and eke by mediacioun of thin eye to knowe the altitude of sterres by night.
Than is there a large pyn in manere of an extre, that goth thorugh the hole that halt the tables of the clymates and the riet in the wombe of the moder; thorugh which pyn ther goth a litel wegge, which that is clepid the hors, that streynith all these parties to-hepe. Thys forseide grete pyn in manere of an extre is ymagyned to be the Pool Artik in thyn Astralabie.
The wombe syde of thyn Astrelabie is also divided with a longe cros in 4 quarters from est to west, fro southe to northe, fro right syde to left side, as is the bakside.
The bordure of which wombe side is divided fro the point of the est lyne unto the point of the south lyne under the ring, in 90 degrees; and by that same proporcioun is every quarter divided, as is the bakside. That amountith 360 degrees. And understond wel that degres of this bordure ben aunswering and consentrike to the degrees of the equinoxiall, that is dividid in the same nombre as every
The plate under the riet is discrived with 3 cercles, of whiche the leest is clepid the cercle of Cancre by cause that the heved of Cancre turnith evermo consentrik upon the same cercle. In this heved of Cancer is the grettist declinacioun northward of the sonne, and therfore is he clepid solsticium of somer; which declinacioun, after Ptholome, is 23 degrees and 50 minutes as wel in Cancer as in Capricorn. This signe of Cancer is clepid the tropik of somer, of tropos, that is to seien "ageynward." For than beginneth the sonne to passen from us-ward.
The myddel cercle in wydnesse, of these 3, is clepid the cercle equinoxiall, upon which turnith evermo the hevedes of Aries and Libra. And understond wel that evermo thys cercle equinoxiall turnith justly from verrey est to verrey west as I have shewed the in the speer solide. This same cercle is clepid also Equator, that is the weyer of the day; for whan the sonne is in the hevedes of Aries and Libra, than ben the dayes and the nightes ylike of lengthe in all the world. And therfore ben these 2 signes called the equinoxiis. And all that moeveth withinne the hevedes of these Aries and Libra, his moevyng is clepid northward; and all that moevith withoute these hevedes, his moevyng is clepid southward, as fro the equinoxiall. Tak kep of these latitudes north and south, and forget it nat. By this cercle equinoxiall ben considred the 24 houres of the clokke; for evermo the arisyng of 15 degrees of the equinoxiall makith an houre equal of the clokke. This equinoxiall is clepid the gurdel of the first moeving, or ellis of the firste moevable. And note that the firste moevyng is clepid moevyng of the firste moevable of the 8 speer, which moeving is from est to west, and eft ageyn into est. Also it is clepid girdel of the firste moeving for it departith the firste moevable, that is to seyn the spere, in two like partyes evene distantz fro the poles of this world.
The widest of these 3 principale cercles is clepid the cercle of Capricorne, by cause that the heved of Capricorne turneth evermo consentrik upon the same cercle. In the heved of this forseide Capricorne is the grettist declinacioun southward of the sonne, and therfore it is clepid the solsticium of wynter. This signe of Capricorne is also clepid the
Upon this forseide plate ben compassed certeyn cercles that highten almycanteras, of whiche somme of hem semen parfit cercles and somme semen inparfit. The centre that stondith amyddes the narwest cercle is clepid the cenyth. And the netherist cercle, or the firste cercle, is clepid the orizonte, that is to seyn, the cercle that divideth the two emysperies, that is, the partie of the hevene above the erthe and the partie bynethe. These almykanteras ben compowned by 2 and 2, all be it so that on diverse Astrelabies somme almykanteras ben divided by oon, and somme by two, and somme by thre, after the quantite of the Astrelabie. This forseide cenyth is ymagined to ben the verrey point over the crowne of thin heved. And also this cenyth is the verray pool of the orizonte in every regioun.
From this cenyth, as it semeth, there comen a maner croked strikes like to the clawes of a loppe, or elles like the werk of a wommans calle, in kervyng overthwart the almykanteras. And these same strikes or divisiouns ben clepid azimutz, and thei dividen the orisounte of thin Astrelabie in 24 divisiouns. And these azymutz serven to knowe the costes of the firmament, and to othre conclusions, as for to knowe the cenyth of the sonne and of every sterre.
Next these azymutz, under the cercle of Cancer, ben there 12 divisiouns embelif, muche like to the shap of the azemutz, that shewen the spaces of the houres of planetes.
The riet of thin Astrelabie with thy zodiak, shapen in manere of a net or of a lopweb after the olde descripcioun, which thou maist turnen up and doun as thiself liketh, contenith certein nombre of steires fixes, with her longitudes and latitudes determinat, yf so be that the maker have not errid. The names of the sterres ben writen in the margyn of the riet there as thei sitte, of whiche sterres the smale point is clepid the centre. And understond also that alle the sterres sitting within the zodiak of thin Astrelabie ben clepid sterres of the north, for thei arise by northe the est lyne. And all the remenaunt fixed oute of the zodiak ben clepid sterres of the south. But I seie not that thei arisen alle by southe the est lyne; witnesse on Aldeberan and Algomeysa. Generaly understond this
Thy zodiak of thin Astrelabie is shapen as a compas which that contenith a large brede as after the quantite of thyn Astrelabie, in ensample that the zodiak in hevene is ymagyned to ben a superfice contenyng a latitude of 12 degrees, whereas alle the remenaunt of cercles in the hevene ben ymagyned verrey lynes withoute eny latitude. Amiddes this celestial zodiak is ymagined a lyne which that is clepid the ecliptik lyne, under which lyne is evermo the wey of the sonne. Thus ben there 6 degres of the zodiak on that oo syde of the lyne and 6 degrees on that othir. This zodiak is dividid in 12 principale divisiouns that departen the 12 signes, and, for the streitnesse of thin Astrolabie, than is every smal divisioun in a signe departed by two degrees and two, I mene degrees contenyng 60 mynutes. And this forseide hevenysshe zodiak is clepid the cercle of the signes, or the cercle of the bestes, for "zodia" in langage of Grek sowneth "bestes" in Latyn tunge. And in the zodiak ben the 12 signes that han names of bestes, or ellis for whan the sonne entrith in eny of tho signes he takith the propirte of suche bestes, or ellis for that the sterres that ben ther fixed ben disposid in signes of bestes or shape like bestes, or elles whan the planetes ben under thilke signes thei causen us by her influence operaciouns and effectes like to the operaciouns of bestes.
And understond also that whan an hot planete cometh into an hot signe, than encrescith his hete; and yf a planete be cold, than amenusith his coldnesse by cause of the hoote sygne. And by thys conclusioun maist thou take ensample in alle the signes, be thei moist or drie, or moeble or fixe, reknyng the qualite of the planete as I first seide. And everich of these 12 signes hath respect to a certeyn
This zodiak, which that is part of the 8 speer, over-kervith the equinoxial, and he over-kervith him ageyn in evene parties; and that oo half declineth southward; and that othir northward, as pleinly declarith the Tretys of the Speer.
Than hast thou a label that is shapen like a reule, save that it is streit and hath no plates on either ende with holes. But with the smale point of the forseide label shalt thou calcule thin equaciouns in the bordure of thin Astralabie, as by thin almury.
Thin almury is clepid the denticle of Capricorne, or ellis the calculer. This same almury sitt fix in the heved of Capricorne, and it serveth of many a necessarie conclusioun in equacions of thinges as shal be shewid.
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