A Treatise on the Astrolabe
Geoffrey Chaucer, appr. 1391
Lyte Lowys my sone, I aperceyve wel by certeyne evydences thyn
abilite to lerne sciences touching nombres and proporciouns; and as wel
considre I thy besy praier in special to lerne the tretys of the
Astrelabie. Than for as mochel as a philosofre saith, "he wrappith
him in his frend, that condescendith to the rightfulle praiers of his
frend," therfore have I latitude of Oxenforde; upon which, by
mediacioun of this litel tretys, I purpose to teche the a certein nombre
of conclusions aperteynyng to the same instrument. I seie a certein of
conclusions, for thre causes. The first cause is this: truste wel that
alle the conclusions that han be founde, or ellys possibly might be founde
in so noble an instrument as is an Astrelabie ben unknowe parfitly to eny
mortal man in this regioun, as I suppose. An-other cause is this, that
sothly in any tretis of the Astrelabie that I have seyn there be somme
conclusions that wol not in alle thinges parformen her bihestes; and somme
of hem ben to harde to thy tendir age of ten yeer to conceyve.
This tretis, divided in 5 parties, wol I shewe the under full light
reules and naked wordes in Englissh, for Latyn ne canst thou yit but
small, my litel sone. But natheles suffise to the these trewe conclusions
in Englissh as wel as sufficith to these noble clerkes Grekes these same
conclusions in Grek; and to Arabiens in Arabik, and to Jewes in Ebrew, and
to the Latyn folk in Latyn; whiche Latyn folk had hem first out of othere
dyverse langages, and writen hem in her owne tunge, that is to seyn, in
Latyn. And God woot that in alle these langages and in many moo han these
conclusions ben suffisantly lerned and taught, and yit by diverse reules;
right as diverse pathes leden diverse folk the righte way to Rome. Now wol
I preie mekely every discret persone that redith or herith this litel
tretys to have my rude endityng for excusid, and my superfluite of wordes,
for two causes. The first cause is for that curious endityng and hard
sentence is ful hevy at onys for such a child to lerne. And the secunde
cause is this, that sothly me semith better to writen unto a child twyes a
god sentence, than he forgete it onys.
And Lowys, yf so be that I shewe the in my light Englissh as trewe
conclusions touching this mater, and not oonly as trewe but as many and as
subtile conclusiouns, as ben shewid in Latyn in eny commune tretys of the
Astrelabie, konne me the more thank. And preie God save the king, that is
lord of this langage, and alle that him feith berith and obeieth, everich
in his degre, the more and the lasse. But considre wel that I ne usurpe
not to have founden this werk of my labour or of myn engyn. I n'am but a
lewd compilator of the labour of olde astrologiens, and have it translatid
in myn Englissh oonly for thy doctrine. And with this swerd shal I sleen
Prima pars. -The firste partie of this tretys shal reherse the
figures and the membres of thyn Astrelabie by cause that thou shalt have
the gretter knowing of thyn owne instrument.
Secunda pars. -The secunde partie shal techen the worken the
verrey practik of the forseide conclusiouns, as ferforth and as narwe as
may be shewed in so small an instrument portatif aboute. For wel woot
every astrologien that smallist fraccions ne wol not be shewid in so small
an instrument as in subtile tables calculed for a cause.
Tertia pars. -The thirde partie shal contene diverse tables of
longitudes and latitudes of sterres fixe for the Astrelabie, and tables of
the declinacions of the sonne, and tables of longitudes of citees and
townes; and tables as well for the governaunce of a clokke, as for to
fynde the altitude meridian; and many anothir notable conclusioun after
the kalenders of the reverent clerkes, Frere J. Somes and Frere N. Lenne.
Quarta pars. -The fourthe partie shal ben a theorike to declare
the moevyng of the celestiall bodies with the causes The whiche fourthe
partie in speciall shal shewen a table of the verrey moeving of the mone
from houre to houre every day and in every signe after thyn almenak. Upon
which table there folewith a canoun suffisant to teche as wel the manere
of the worchynge of the same conclusioun as to knowe in oure orizonte with
which degre of the zodiak that the mone arisith in any latitude, and the
arisyng of any planete after his latitude fro the ecliptik lyne.
Quinta pars. -The fifthe partie shal be an introductorie, after
the statutes of oure doctours, in which thou maist lerne a gret part of
the generall rewles of theorik in astrologie. In which fifthe partie shalt
thou fynden tables of equaciouns of houses after the latitude of Oxenforde;
and tables of dignitees of planetes, and othere notefull thinges, yf God
wol vouche saaf and his Moder the Maide, moo then I behete.
Here begynneth the descripcioun of thin Astralabie.
1. Thyn Astrolabie hath a ring to putten on the thombe of thi right
hond in taking the height of thinges. And tak kep, for from henes
forthward I wol clepen the heighte of any thing that is taken by the rewle
"the altitude," withoute moo wordes.
2. This ryng renneth in a maner toret fast to the moder of thyn
Astrelabie in so rowm a space that it distourbith not the instrument to
hangen after his right centre.
3. 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 webbe of a loppe.
4. 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 clepid the north lyne, or ellis the lyne of
5. 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
6. Tlle 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.
7. 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 seien, mynutes of an houre.
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 nombre of the
degrees of thoo signes be writen in augrym above, and with longe
divisiouns fro 5 to 5, dyvidid fro the tyme 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.
9. Next this folewith the cercle of the daies, that ben figured in
manere of degres, that contenen in nombre 365, dividid also with longe
strikes fro 5 to 5, and the nombre in augrym writen under that cercle.
10. 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 thus, somme for her propirtees and
somme by statutes of lordes 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, September 30, October 31, November 30, December
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
11. 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.
12. 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.
13. 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.
14. 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
15. The wombe syde of thyn Astrelabie is also divided with a longe
croys in 4 quarters from est to west, fro southe to northe, fro right syde
to left side, as is the bakside.
16. 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 understondwel that degres of this bordure ben
aunswering and consentrike to the degrees of the equinoxiall, that is
dividid in the same nombre as every lo othir cercle is in the highe hevene.
This same bordure is divided also with 23 lettres capitals and a small
crosse (+) above the south lyne, that shewith the 24 houres equals of the
clokke. And, as I have seid, 5 of these degres maken a myle wey, and 3
milewei maken an houre. And every degre ot thys bordure contenith 4
minutes, and every minute 60 secundes. Now have I told the twyes.
17. The plate under the riet is discrived with 3 principal 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 lo 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
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 north- ward; 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 first moevable. And note that the first moevyng is clepid
moevyng of the first moevable of the 8 speer, which moeving is from est
into west, and eft ageyn into est. Also it is clepid girdel of the
first.moeving for it departith the first moevable, that is to seyn the
spere. in two llke 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 forseid 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 tropic of wynter, for than begynneth the sonne to come ageyn to us-
18. 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 first cercle, is clepid the
orizonte, that is to seyn, the cercle that divideth the two emysperies,
that is, the partie of the lo 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 ori- zonte in
19. 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.
20. Next these azymutz, under the cercle of Cancer, ben there 12
divisouns embelif, muche like to the shap of the azemutz, that shewen the
spaces of the hollres of planetes.
21. The riet of thin Astrelabie with thy zodiak, shapen in manere of a
net or of a lopwebbe after the olde descripcioun, which thou maist turnen
up and doun as thiself liketh, contenith certein nombre of sterres 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 lo 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 Algomeyse. Generaly
understond this rewle, that thilke sterres that ben clepid sterres of the
north arisen rather than the degre of her longitude, and alle the sterres
of the south arisen after the degre of her longitude - this is to seyn,
sterres fixed in thyn Astrelabie. The mesure of the longitude of sterres
is taken in the lyne ecliptik of hevene, under which lyne, whan that the
sonne and the mone be lyne-right, or ellis in the superficie of this lyne,
than is the eclipse of the sonne or of the mone, as I shal declare, and
eke the cause why. But sothly the ecliptik lyne of thy zodiak is the
utterist bordure of thy zodiak there the degrees be marked.
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 Iynes 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 divisoun 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 into eny of tho signes he takith the propirte of suche
bestes, or ellis that for 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 parcel of the body of a man, and hath
it in governaunce; as Aries hath thin heved, and Taurus thy nekke and thy
throte, Gemini thin armholes and thin armes, and so furth, as shall be
shewid more pleyn in the 5 partie of this tretis.
This zodiak, which that is part of the speer, over-kervith the
equinoxial, and-he over-kervith him ageyn in evene parties; and that oo
half declineth so 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.
Here endith the descripcioun of the Astrelabie and here begynne the
conclusions of the Astrelabie.
1. To fynde the degre in which the sonne is day by day, after his cours
Rekne and knowe which is the day of thy month, and ley thy rewle up
that same day, and than wol the verrey poynt of thy rewle sitten in the
bordure upon the degre of thy sonne.
Ensample as thus: -The yeer of oure Lord 1391, the 12 day of March at
midday, I wolde knowe the degre of the sonne. I soughte in the bakhalf of
myn Astrelabie and fond the cercle of the daies, lo the whiche I knowe by
the names of the monthes writen under the same cercle. Tho leyde I my
reule over this forseide day, and fond the point of my reule in the
bordure upon the firste degre of Aries, a litel within the degre. And thus
knowe I this conclusioun.
Anothir day I wolde knowen the degre of my sonne, and this was at
midday in the 13 day of December. I fond the day of the month in manere as
I seide; tho leide I my rewle upon this forseide 13 day, and fond the
point of my rewle in the bordure upon the firste degre of Capricorne a
lite within the degre. And than had I of this conclusioun the ful
2. To knowe the altitude of the sonne or of othre celestial bodies.
Put the ryng of thyn Astrelabie upon thy right thombe, and turne thi
lift syde ageyn the light of the sonne; and remewe thy rewle up and doun
til that the stremes of the sonne shine thorugh bothe holes of thi rewle.
Loke than how many degrees thy rule is areised fro the litel crois upon
thin est lyne, and tak there the altitude of thi sonne. And in this same
wise maist thow knowe by night the alti- tude of the mone or of brighte
This chapitre is so generall evere in oon that there nedith no more
declaracioun; but forget it not.
3. To knowe every tyme of the day by light of the sonne; and every
tyme of the nyght by the sterres fixe; and eke to knowe by nyght or by day
the degre of eny signe that ascendith on the est orisonte, which that is
clepid comounly the ascendent, or ellis horoscopum.
Tak the altitude of the sonne whan the list, as I have seid, and set
the degre of the sonne, in caas that it be beforn the myddel of the day,
among thyn almykanteras on the est syde of thin Astrelabie; and if it be
after the myddel of the day, set the degre of thy sonne upon the west syde.
Take this manere of settyng for a general rule, ones for evere. And whan
thou hast set the degre of thy sonne upon as lo many almykanteras of
height as was the altitude of the sonne taken by thy rule, ley over thi
label upon the degre of the sonne; and than wol the point of thi labell
sitte in the bordure upon the verrey tyde of the day.
Ensample as thus: -The yeer of oure lord 1391, the 12 day of March, I
wolde knowe the tyde of the day. I tok the altitude of my sonne, and fond
that it was 25 degrees and 30 of minutes of height in the bordure on the
bak side. Tho turned I myn Astrelabye, and by cause that it was beforn
mydday, I turned my riet and sette the degre of the sonne, that is to seyn
the first degre of Aries, on the right side of myn Astrelabye upon 25
degrees and 30 mynutes of height among myn almykanteras. Tho leide I my
label upon the degre of my sonne, and fond the point of my label in the
bordure upon a capital lettre that is clepid an X. Tho rekned I alle the
capitale lettres fro the lyne of mydnight unto this forseide lettre X, and
fond that it was 9 of the clokke of the day. Tho loked I doun upon the est
orizonte, and fond there the 20 degre of Geminis ascendyng, which that I
tok for myn ascendent. And in this wise had I the experience for evermo in
which manere I shulde knowe the tyde of the day and eke myn ascendent.
Tho wolde I wite the same nyght folewyng the houre of the nyght, and
wroughte in this wise: - Among an heep of sterres fixe it liked me for to
take the altitude of the faire white sterre that is clepid Alhabor, and
fond hir sittyng on the west side of the lyne of midday, 12 degrees of
heighte taken by my rewle on the bak side. Tho sette I the centre of this
Alhabor upon 12 degrees among myn almykanteras upon the west side, by
cause that she w as founde on the west side. Tho leyde I my label over the
degre of the sonne, that was discendid under the west orisounte, and
rekned all the lettres capitals fro the lyne of midday unto the point of
my Iabel in the bordure, and fond that it was passed 9 of the c lokke the
space of 10 degrees. Tho lokid I doun upon myn est orisounte, and fond
there 10 degrees of Scorpius ascendyng, whom I tok for myn ascendent. And
thus lerned I to knowe onys for evere in which manere I shuld come to the
houre of the nyght, and to myn ascendent, as verrely as may be taken by so
smal an instrument.
But natheles this rule in generall wol I warne the for evere: - Ne make
the nevere bold to have take a just ascendent by thin Astrelabie, or elles
to have set justly a clokke, whan eny celestial body by which that thou
wenyst governe thilke thinges be nigh the south Iyne. For trust wel, whan
the sonne is nygh the meridional lyne, the degre of thc sonne renneth so
longe consentrik upon the almykanteras that sothly thou shalt erre fro the
just ascendent. The same conclusion sey I by the centre of eny sterre fix
by nyght. And more over, by experience I wot wel that in our orisounte,
from xi of the clokke unto oon of the clokke, in taking of a just
ascendent in a portatif Astrelabie it is to hard to knowe - I mene from xi
of the clokke before the houre of noon til oon of the clokke next folewyng.
4. A special declaracioun of the ascendent.
The ascendent sothly, as wel in alle nativites as in questions and
eleccions of tymes, is a thing which that these astrologiens gretly
observen. Wherfore me semeth convenyent, syth that I speke of the
ascendent, to make of it speciall declaracioun.
The ascendent sothly, to take it at the largest, is thilke degre that
ascendith at eny of these forseide tymes upon the est orisounte. And
therfore, yf that eny planete ascende at thatt same tyme in thilke
forseide degre, than hath he no latitude fro the ecliptik lyne, but he is
than in the degre of the ecliptik which that is the degre of his
longitude. Men sayn that thilke planete is in horoscopo.
But sothly the hous of the ascendent, that is to seyn, the first hous
or the est angle, is a thing more brod and large. For, after the statutes
of astrologiens, what celestial body that is 5 degrees above thilke degre
that ascendith, or withinne that nombre, that is to seyn neer the degree
that ascendith, yit rekne they thilke planete in the ascendent. And what
planete that is under thilke degre that ascendith the space of 25 degres,
yit seyn thei that thilke planete is "like to him that is the hous of
the ascendent." But sothly, if he passe the boundes of these forseide
spaces, above or bynethe, thei seyn that the planete is "fallyng fro
the ascendent." Yit saien these astrologiens that the ascendent and
eke the lord of the ascendent may be shapen for to be fortunat or
infortunat, as thus: - A "fortunat ascendent " clepen they whan
that no wicked planete, as Saturne or Mars or elles the Tayl of the
Dragoun, is in the hous of the ascendent, ne that no wicked planete have
noon aspect of enemyte upon the ascendent. But thei wol caste that thei
have a fortunat planete in hir ascendent, and yit in his felicite; and
than sey thei that it is wel. Further over thei seyn that the infortunyng
of an ascendent is the contrarie of these forseide thinges. The lord of
the ascendent, sey thei that he is fortunat whan he is in god place fro
the ascendent, as in an angle, or in a succident where as he is in hys
dignite and comfortid with frendly aspectes of planetes and wel resceyved;
and eke that he may seen the ascendent; an that he be not retrograd, ne
combust, ne joyned with no shrewe in the same signe; ne that he be not in
his discencioun, ne joyned with no planete in his descencioun, ne have
upon him noon aspect infortunat; and than sey thei that he is well.
Natheles these ben observaunces of judicial matere and rytes of payens,
in whiche my spirit hath no feith, ne knowing of her horoscopum.
For they seyn that every signe is departid in thre evene parties by 10
degrees, and thilke porcioun they clepe a face. And although that a
planete have a latitude fro the ecliptik, yit sey somme folk, so that the
planete arise in that same signe with eny degre of the forseide face in
which his longitude is rekned, that yit is the planete in horoscopo,
be it in nativyte or in eleccion, etc.
5. To knowe the verrey equacioun of the degre of the sonne yf so be
that it falle bitwene two almykanteras.
For as muche as the almykanteras in thin Astrelabie ben compowned by
two and two, where as somme almykanteras in sondry astrelabies be
compowned by 1 and 1, or elles by 3 and 3, it is necessarie to thy lernyng
to teche the first to knowe and worke with thin owne instrument. Wherfore
whan that the degre of thi sonne fallith bytwixe 2 almykanteras, or ellis
yf thin almykanteras ben graven with over-gret a poynt of a compas (for
bothe these thinges may causen errour as wel in knowing of the tide of the
day, as of the verrey ascendent), thou must worken in this wise: -
Set the degre of thy sonne upon the hyer almykanteras of bothe, and
wayte wel where as thin almury touchith the bordure and set there a prikke
of ynke. Sett doun agayn the degre of the sunne upon the nether
almykanteras of bothe, and sett there another pricke. Remeve than thin
almury in the bordure evene amiddes bothe prickes, and this wol lede
justly the degre of thi sonne to sitte atwixe bothe almykanteras in his
right place. Ley than thy label over the degre of thi sonne, and fynd in
the bordure the verrey tyde of the day, or of the night.
Andasverrailyshaltthoufynde upon thin est orisonte thin ascendent.
6. To knowe the spryng of the dawenyng and the ende of the evenyng,
the whiche ben called the two crepuscules.
Set the nadir of thy sonne upon 18 degrees of height among thyn
almykanteras on the west syde; and ley thy label on the degre of thy sonne,
and than shal the point of thy label shewen the spryng of the day. Also
set the nader of thy sonne upon 18 degrees of height among thin
almykanteras on the est side, and ley over thy lahel upon the degre of the
sonne, and with the point of thy label fynd in the bordure lo the ende of
the evenyng, that is verrey nyght.
The nader of the sonne is thilke degre that is opposyt to the degre of
the sonne, in the 7 signe, as thus: - every degre of Aries by ordir is
nadir to every degre of Libra by ordre, and Taurus to Scorpioun, Gemini to
Sagittarie, Cancer to Capricorne, Leo to Aquarie, Virgo to Pisces. And if
eny degre in thy zodiak be derk, his adir shal declare hym.
7. To knowe the arch of the day, that sorne folk callen the day
artificiall, fro sonne arisyng tyl it go to reste.
Set the degre of thi sonne upon thin est DriSonte and ley thy label on
the degre of the sonne, and at the point of thy label in the bordure set a
pricke. Turne than thy riet aboute tyl the degre of thy sonne sitte upon
the west orisonte, and ley thy label upon the same degre of the sonne, and
at the poynt of thy label set there another pricke. Rekne than the
quantite of tyme in the bordure bitwixe bothe prickes, and tak there thyn
arch of the day. The remenaunt of the bordure under the orisonte is the
arch of the nyght. Thus maist thou rekne bothe arches, or every porcioun,
of whether that the liketh. And by this manere of worching maist thou se
how longe that eny sterre fix dwelleth above the erthe, fro tyme that he
riseth til he go to reste. But the day naturall that is to seyn 24 houres,
is the revolu- cioun of the equinoxial with as muche partie of the zodiak
as the sonne of his propre moeving passith in the mene while.
8. To turne the houres inequales in houres equales.
Know the nombre of the degrees in the houres inequales, and depart hem
by 15, and tak there thin houres equales.
9. To knowe the quantite of the day vulgar, that is to seyn fro
spryng of the day unto verrey nyght.
Know the quantite of thy crepuscles, as I have taught in the 2 chapitre
bifore, and adde hem to the arch of thy day artificial, and tak there the
space of all the hool day vulgar unto verrey night. The same manere maist
thou worche to knowe the quantite of the vulgar nyght.
10. To knowe the quantite of houres in, equales by day.
Understond wel that these houres inequales ben clepid houres of
planetes. And understond wel that som tyme ben thei lenger by day than by
night, and som tyme the contrarie. But understond wel that evermo generaly
the houre inequal of the day with the houre inequal of the night contenen
30 degrees of the bordure, which bordure is evermo answeryng to the
degrees of the equinoxial. Wherfore departe the arch of the day artificial
in 12, and tak there the quantite of the houre inequale by day. And if
thou abate the quantite of the houre inequale by day out of 30, than shal
the remenaunt that levith parforme the houre inequale by night.
11. To knowe the quantite of houres equales.
The quantite of houres equales, that is to seyn the houres of the
clokke, ben departid by 15 degrees alredy in the bordure of thin Astrelaby,
as wel by night as by day, generaly for evere. What nedith more
Wherfore whan the list to knowe how many houres of the clokke ben
passed, or eny part of eny of these houres that ben passed, or ellis how
many houres lo or parties of houres ben to come fro such a tyme to such a
tyme by day or by night, know the degre of thy sonne, and ley thy label on
it. Turne thy ryet aboute joyntly with thy label, and with the poynt of it
rekne in the bordure fro the sonne ariste unto that same place there thou
desirist, by day as by nyght. This conclusioun wol I declare in the last
chapitre of the 4 partie of this tretys so openly that ther shal lakke no
word that nedith to the declaracioun.
12. Special declaracioun of the houres of planetes.
Understond wel that evermo, fro the arisyng of the sonne til it go to
reste, the nadir of the sonne shal shewe the houre of the planete; and fro
that tyme forward al the night til the sonne arise, than shal the verrey
degre of the sonne shewe the houre of the planete.
Ensample as thus: -The xiij day of March fyl upon a Saturday,
peraventure, and atte risyng of the sonne I lo fond the secunde degre of
Aries sittyng upon myn est orisonte, all be it that it was but litel. Than
fond I the 2 degre of Libra, nadir of my sonne, discending on my west
orisonte, upon which west orisonte every day generaly, atte sonne arist,
entrith the houre of every planete, after which planete the day berith his
name, and endith in the next strike of the plate under the forseide west
orisonte. And evere as the sonne clymbith upper and upper, so goth his
nadir downer and downer, teching by suche strikes the houres of planetes
by ordir as they sitten in the hevene. The firste houre inequal of every
Saturday is to Saturne, and the seconde to Jupiter, the thirde to Mars,
the fourthe to the sonne, the fifte to Venus, the sixte to Mercurius, the
seventhe to the mone. And then ageyn the 8 houre is to Saturne, the 9 is
to Jupiter, the 10 to Mars, the 11 to the sonne, the 12 to Venus. And now
is my sonne gon to reste as for that Saturday. Than shewith the verrey
degre of the sonne the houre of Mercurie entring under my west orisonte at
eve; and next hilr succedith the mone, and so furth by ordir planete after
planete in houre after houre, all the nyght longe til the sonne arise. Now
risith the sonne that Sonday by the morwe, and the nadir of the sonne upon
the west orisonte shewith me the entring of the houre of the forseide
sonne. And in this manere succedith planete under planete fro Saturne unto
the mone, and fro the mone up ageyn to Saturne, houre after houre generaly.
And thus have I this conclusyoun.
13. To knowe the altitude of the sonne in myddes of the day that is
clepid the altitude meridian.
Set the degre of the sonne upon the lyne meridional, and rekne how many
degrees of almykanteras ben bitwyxe thin est orisonte and the degre of thy
sonne; and tak there thin altitude meridian, this to seyn, the highest of
the sonne as for that day. So maist thou knowe in the same lyne the
heighest cours that eny sterre fix clymbeth by night. This is to seyn that
whan eny sterre fix is passid the lyne merid- ional, than begynneth it to
descende; and so doth the sonne.
14. To knowe the degre of the sonne by thy ryet, for a maner
Sek besily with thy rule the highest of the sonne in mydde of the day.
Turne than thin Astrelabie, and with a pricke of ynke marke the nombre of
that same altitude in the lyne meridional; turne than thy ryet aboute tyl
thou fynde a degre of thy zodiak according with the pricke, this is to
seyn, sitting on the pricke. And in soth thou shalt finde but 2 degrees in
all the zodiak of that condicioun; and yit lo thilke 2 degrees ben in
diverse signes. Than maist thou lightly, by the sesoun of the yere, knowe
the signe in which that is the sonne.
15. To knowe which day is lik to which day as of lengthe.
Loke whiche degrees ben ylike fer fro the hevedes of Cancer and
Capricorne, and loke when the sonne is in eny of thilke degrees; than ben
the dayes ylike of lengthe. This is to seyn that as longe is that day in
that month, as was such a day in such a month- there varieth but litel.
Also, yf thou take 2 dayes naturales in the yere ylike fer fro either
point of the equinoxiall in the opposyt parties, than as longe is the day
artificiall of that oon day as is the night of that othir, and the
16. This chapitre is a maner declaracioun to conclusiouns that
Understond wel that thy zodiak is departed in two halve circles, as fro
the heved of Capricorne unto the heved of Cancer, and ageynward fro the
heved of Cancer unto the heved of Capricorne. The heved of Capricorne is
the lowest point where as the sonne goth in wynter, and the heved of
Cancer is the heighist point in which the sonne goth in somer. And
therfore understond wel that eny two degrees lo that ben ylike fer fro eny
of these two hevedes, truste wel that thilke two degrees hen of ilike
declinacioun, be it southward or northward, and the daies of hem ben ilike
of lengthe and the nyghtes also, and the shadewes ilyke, and the altitudes
ylike atte midday for evere.
17. To knowe the verrey degre of eny maner sterre, straunge or
unstraunge, after his longitude; though he be indetermynat in thin
Astralabye, sothly to the trouthe thus he shal be knowe.
Tak the altitude of this sterre whan he is on the est syde of the lyne
meridionall, as neigh as thou mayst gesse; and tak an ascendent anon right
by som manere sterre fix which that thou knowist; and forget not the
altitude of the firste sterre ne thyn ascendent. And whan that this is
don, aspye diligently whan this same firste sterre passith eny thyng the
south westward; and cacche him anon right in the same nombre of altitude
on the west syde of this lyne meridional, as he was kaught on the est syde;
and tak a newe ascendent anon-ryght by som manere sterre fix which that
thou knowist, and forget not this secunde ascendent. And whan that this is
don, rekne than how many degrees ben bitwixe the first ascendent and the
secunde ascendent; and rekne wel the myddel degre bitwene bothe
ascendentes, and set thilke myddel degre upon thyn est orizonte; and wayte
than what degre that sitte upon the Iyne meridional, and tak there the
verrey degre of the ecliptik in which the sterre stondith for the tyme.
For in the ecliptik is the longitude of a celestiall body rekned, evene
fro the heved of Aries unto the ende of Pisces; and his latitude is rekned
after the quantite of his declynacioun north or south toward the polys of
As thus: -Yif it be of the sonne or of eny fix sterre, rekne hys
latitude or his declinacioun fro the equinoxiall cercle; and if it be of a
planete, rekne than the quantite of his latitude fro the ecliptik lyne,
all be it so that fro the equinoxiall may the declinacioun or the latitude
of eny body celestiall be rekned after the site north or south and after
the quantite of his declinacioun. And right so may the latitude or the
declinacioun of eny body celestiall, save oonly of the sonne, after hys
site north or south and after the quantite of his declinacioun. be rekned
fro the ecliptik lyne; fro which lyne alle planetes som tyme declinen
north or south save oonly the forseide sonne.
18. To knowe the degrees of longitudes of fixe sterres after that
they be determynat in thin Astrelabye, yf so be that thei be trewly sette.
Set the centre of the sterre upon the lyne meridionall, and tak kep of
thy zodiak, and loke what degre of eny signe that sitte upon the same lyne
meridionall at that same tyme, and tak there the degre in which the sterre
stondith; and with that same degre cometh that same sterre unto that same
lyne fro the orisonte.
19. To knowe with which degre of the zodiak eny sterre fix in thin
Astrelabie arisith upon the est orisonte, all though his dwellyng be in
Set the centre of the sterre upon the est orisonte, and loke what degre
of eny signe that sitt upon the same orisonte at that same tyme. And
understond wel that with that same degre arisith that same sterre.
And thys merveylous arisyng with a straunge degre in another signe is
by cause that the latitude of the sterre fix is either north or south fro
the equi- noxiall. But sothly the latitudes of planetes be comounly
rekened fro the ecliptyk, by cause that noon of hem declyneth but fewe
degrees out fro the brede of the zodiak. And tak god kep of this chapitre
of arisyng of celestialle bodies; for truste wel that neyther mone ne
sterre, as in our embelif orisonte, arisith with that same degre of his
longitude save in oo cas, and that is whan they have no latitude fro the
ecliptyk lyne. But natheles som tyme is everich of these planetes under
the same lyne.
20. To knowe the declinacioun of eny degre in the zodiak fro the
Set the degre of eny signe upon the lyne meridionall, and rekne hys
altitude in the almykanteras fro the est orisonte up to the same degre set
in the forseide lyne, and set there a prikke; turne up than thy riet, and
set the heved of Aries or Libra in the same meridionall lyne, and set
there a nother prikke. And whan that this is don, considre the altitudes
of hem bothe; for sothly the difference of thilke alti- tudes is the
declinacioun of thilke degre fro the equinoxiall. And yf it so be that
thilke degre be northward fro the equinoxiall, than is his declinacyoun
north; yif it be southward, than is it south.
21. To knowe for what latitude in eny regioun the almykanteras of
eny table ben com powned .
Rekene how many degrees of almykanteras in the meridionall lyne ben fro
the cercle equinoxiall unto the cenyth, or elles from the pool artyk unto
the north orisonte; and for so gret a latitude, or for so smal a latitude,
is the table compowned.
22. To know in speciall the latitude of oure countre, I mene after
the latitude of Oxenford, and the height of oure pool.
Understond wel that as fer is the heved of Aries or Libra in the
equinoxiall fro oure orisonte as is the cenyth fro the pool artik; and as
high is the pool artik fro the orisonte as the equinoxiall is fer fro the
cenyth. I prove it thus by the latitude of Oxenford: understond wel that
the height of oure pool artik fro oure north orisonte is 51 degrees and 50
mynutes; than is the cenyth fro oure pool artik 38 degrees and 10 mynutes;
than is the equinoxial from oure cenyth 51 degrees and 50 mynutes; than is
oure south orisonte from oure equinoxiall 38 degres and 10 mynutes.
Understond wel this rekenyng. Also forget not that the cenyth is 90
degrees of height from oure orisonte, and oure equinoxiall is 90 degres
from oure pool artik. Also this shorte rule is soth, that the latitude of
eny place in a regioun is the distaunce fro the cenyth unto the
23. To prove evidently the latitude of eny place in a regioun by the
preve of the height of the pool artik in that same place.
In som wynters nyght whan the firmament is cler and thikke sterred,
wayte a tyme til that eny sterre fix sitte lyne-right perpendiculer over
the pool artik, and clepe that sterre A; and wayte another sterre that
sitte lyne right under A, and under the pool, and clepe that sterre F. And
understond wel that F is not considrid but oonly to declare that A sitte
evene over the pool. Tak than anoon-right the altitude of A from the
orisonte, and forget it not; let A and F goo fare wel tyl ageynst the
dawenyng a gret while, and com than ageyn, and abid til that A is evene
under the pool, and under F, for sothly than wol F sitte over the pool,
and A wol sitte under the pool. Tak than eftsonys the altitude of A from
the orisonte, and note as wel his secunde altitude as hys first altitude.
And whan that this is doon, rekene how many degrees that the first
altitude of A excedith his secunde altitude, and tak half thilke porcioun
that is excedid and adde it to his secunde altitude, and tak there the
elevacioun of thy pool, and eke the latitude of thyregioun; for these two
ben of oo nombre, this is to seyn, as many degres as thy pool is elevat,
so muche is the latitude of the regioun.
Ensample as thus: - peraventure the altitude of A in the evenyng is 56
degrees of height; than wol his secunde altitude or the dawenyng be 48
degres that is 8 degrees lasse than 56, that was his first altitude att
even. Tak than the half of 8 and adde it to 48 that was his secunde
altitude, and than hast thou 52. Now hast thou the height of thy pool and
the latitude of the regioun. But understond wel that to prove this con-
clusioun and many another faire conclusioun, tholu must have a plomet
hangyng on a lyne, heygher than thin heved, on a perche; and thilke lyne
must hange evene perpendiculer bytwixe the pool and thin eye; and than
shalt thou seen yf A sitte evene over the pool, and over F atte evene; and
also yf F sitte evene over the pool and over A or day.
24. Another conclusioun to prove the height of the pool artik fro
Tak eny sterre fix that never discendith under the orisonte in thilke
regioun, and considre his heighist altitude and his lowist altitude fro
the orisonte, and make a nombre of bothe these altitudes; tak than and
abate half that nombre, and tak there the elevacioun of the pool artik in
that same regioun.
25. Another conclusioun to prove the latitude of the regioun.
Understond wel that the latitude of eny place in a regioun is verrely
the space bytwexe the cenyth of hem that dwellen there and the equinoxiall
cercle north or south, takyng the mesure in the meridional Iyne, as
shewith in the almykanteras of thin Astrelabye. And thilke space is as
much as the pool artike is high in that same place fro the orisonte. And
than is the depressioun of the pool antartik, that is to seyn, than is the
pool antartik, bynethe the orisonte the same quantite of space neither
more ne lasse.
Than if thou desire to knowe this latitude of the regioun, tak the
altitude of the sonne in the myddel of the day, whan the sonne is in the
hevedes of Aries or of Libra; for than moeveth the sonne in the lyne
equinoxiall; and abate the nombre of that same sonnes altitude out of 90
degrees, and than is the remenaunt of the nombre that leveth the latitude
of that regioun. As thus: - I suppose that the sonne is thilke day at noon
38 degrees of height; abate than 38 oute of 90; so leveth there 52; than
is 52 degrees the latitude. I say not this but for ensample; for wel I wot
the latitude of Oxenford is certeyn minutes lasse, as thow might preve.
Now yf so be that the semeth to longe a tarieng to abide til that the
sonne be in the hevedes of Aries or of Libra, than wayte whan the sonne is
in eny othir degre of the zodiak, and considre the degre of his
declinacioun fro the equinoxiall lyne; and if it so be that the sonnes
declinacioun be northward fro the equinoxiall, abate than fro the sonnes
altitude at non the nombre of his declinacioun, and than hast thou the
height of the hevedes of Aries and Libra. As thus: -My sonne is
peraventure in the first degre of Leoun, 58 degrees and 10 minutes of
height at non, and his declinacioun is almost 20 degrees northward fro the
equinoxiall; abate than thilke 20 degrees of declinacioun out of the
altitude at non; than leveth there 38 degrees and odde minutes. Lo there
the heved of Aries or Libra and thin equinoxiall in that regioun. Also if
so be that the sonnes declinacioun be southward fro the equinoxiall, adde
than thilke declinacioun to the altitude of the sonne at noon, and tak
there the hevedes of Aries and Libra and thin equinoxial; abate than the
height of the equinoxial out of 90 degrees; than leveth there the distance
of the pool of that regioun fro the equinoxiall. Or elles, if the list,
tak the highest altitude fro the equinoxial of eny sterre fix that thou
knowist, and tak the netherest elongacioun (lengthing) fro the same
equinoxial lyne, and work in the manere forseid.
26. Declaracioun of the ascensioun of signes.
The excellence of the spere solide, amonges othir noble conclusiouns,
shewith manyfest the diverse ascenciouns of signes in diverse places, as
wel in the right cercle as in the embelif cercle. These auctours writen
that thilke signe is cleped of right ascensioun with which more part of
the cercle equinoxiall and lasse part of the zodiak ascendith- and thilke
signe ascendith embelif with which lasse part of the equinoxiall and more
part of the zodiak ascendith. Ferther-over they seyn that in thilke
cuntrey where as the senith of hem that dwellen there is in the equinoxial
lyne, and her orisonte passyng by the two poles of this world, thilke folk
han this right cercle and the right orisonte; and evermore the arch of the
day and the arch of the night is there ilike longe- and the sonne twies
every yer passing thorugh the cenith of hir heed, and two someres and two
wynters in a yer han these forseide peple. And the almycanteras in her
Astrelabyes ben streight as a lyne, so as it shewith in the figure.
The utilite to knowe the ascensions of signes in the right cercle is
this: - Truste wel that by mediacioun of thilke ascensions these
astrologiens, by her tables and her instrumentes, knowen verreily the
ascensioun of every degre and minute in all the zodiak in the embelif
cercle, as shal be shewed. And nota that this forseide right
orisonte, that is clepid Orison Rectum, dividith the equinoxial
into right angles; and the embelif orisonte where as the pool is enhaunced
upon the orisonte, overkervith the equinoxiall in embilif angles, as
shewith in the figure.
27. This is the conclusioun to knowe the ascensions of signes in the
right cercle, that is circulus directus.
Set the heved of what signe the lyst to knowe his ascendyng in the
right cercle upon the lyne meridionall, and wayte where thyn almury
touchith the bordure, and set there a prikke; turne than thy riet westward
til that the ende of the forseide signe sitte upon the meridional lyne and
eftsonys wayte where thin almury touchith the bordure, and set there
another pricke. Rekene than the nombre of degres in the bordure bitwixe
bothe prikkes, and tak the ascensioun of the signe in the right cercle.
And thus maist thou werke with every porcioun of thy zodiak.
28. To knowe the ascensions of signes in the embelif cercle in every
regioun, I mene, in circulo obliquo.
Set the heved of the signe which as the list to knowe his ascensioun
upon the est orisonte, and wayte where thin almury touchith the bordure,
and there set a prikke. Turne than thy riet upward til that the ende of
the same signe sitte upon the est orisonte, and wayte eftsonys where as
thin almury touchith the bordure, and set there a nother prikke. Rekene
than the nombre of degrees in the bordure bitwyxe bothe prikkes and tak
there the ascensioun of the signe in the embelif cercle. And understond
wel that alle the signes in thy zodiak, fro the heved of Aries unto the
ende of Virgo, ben clepid signes of the north fro the equinoxiall. And
these signes arisen bitwyxe the verrey est and the verrey north in oure
orisonte generaly for evere. And alle the ignes fro the heved of Libra
unto the ende of Pisces ben clepid signes of the south fro the equinoxial;
and these signes arisen evermore bitwexe the verrey est and the verrey
south in oure orisonte. Also every signe bitwixe the heved of Capricorne
unto the ende of Geminis arisith on oure orisonte in lasse than 2 houres
equales. And these same signes fro the heved of Capricorne unto the ende
of Geminis ben cleped tortuose signes, or croked signes, for thei arise
embelyf on oure orisonte. And these croked signes ben obedient to the
signes that ben of right ascensioun. The signes of right ascencioun ben
fro the heved of Cancer unto the ende of Sagittarie; and these signes
arisen more upright, and thei ben called eke sovereyn signes and everich
of hem arisith in more space than in 2 houres. Of whiche signes Gemini
obeieth to Cancer, and 'raurus to Leo, Aries to Virgo, Pisces to Libra,
Aquarius to Scorpioun, and Capricorne to Sagittarie. And thus evermore 2
signes that ben ilike fer fro the heved of Capricorne obeyen everich of
hem til othir.
29. To knowe justly the 4 quarters of the world, as Est, West,
North, and South.
Tak the altitude of thy sonne whan the list, and note wel the quarter
of the world in which the sonne is for the tyme by the azymutz. Turne than
thin Astrelabie, &nd set the degre of the sonne in the almykanteras of
his altitude on thilke syde that the sonne stant, as is the manere in
takyng of houres, and ley thy label on the degre of the sonne; and rekene
how many degrees of the bordure ben bitwixe the Iyne meridional and the
point of thy label, and note wel that nombre. Turne than ageyn thin
Astrelabie, and set the point of thy gret rule there thou takist thin
altitudes upon as many degrees in his bordure fro his meridional as was
the point of thy label fro the lyne meridional on the wombe side. Take
than thin Astrelabie with bothe hondes sadly and slighly, and lat the
sonne shyne thorugh bothe holes of thy rule, and slighly in thilke shynyng
lat thin Astrelabie kouche adoun evene upon a smothe ground, and than wol
the verrey lyne meridional of thin Astrelabie lye evene south, and the est
Iyne wol Iye est, and the west Iyne west, and the north lyne north, so
that thou worke softly and avysely in the kouching. And thus hast thou the
4 quarters of the firmament.
30. To knowe the altitude of planetes fro the wey of the sonne,
whethir so they be north or south fro the forseide wey.
Loke whan that a planete is in the lyne meridional, yf that hir
altitude be of the same height that is the degre of the sonne for that
day, and than is the planete in the verrey wey of the sonne and hath no
latitude. And if the altitude of the planete be heigher than the degre of
the sonne, than is the planete north fro the wey of the sonne such a
quantite of latitude as shewith by thin almykanteras. And if the altitude
of the planete be lasse than the degre of the sonne, than is the planete
south fro the wey of the sonne such a quantite of latitude as shewith by
thin almykanteras. This is to seyn, fro th(wey where as the sonne went
thilke day but not fro the wey of the sonne in every place of the zodiak.
31. To knowe the cenyth of the arising of the sonne, this is to seyn,
the partie of the orisonte in which that the sonne arisith.
Thou must first considere that the sonne arisith not alwey verrey est,
but somtyme by northe the est and somtyme by south the est. Sothly the
sonne arisith nevere moo verrey est in oure orisonte, but he be in the
heved of Aries or Libra. Now is thin orisonte departed in 24 parties by
thin azimutes in significacioun of 24 parties of the world; al be it so
that shipmen rekene thilke parties in 32. Than is there no more but wayte
iIl which azimut that thy sonne entrith at his arisyng, and take there the
cenith of the arisyng of the sonne.
The manere of the divisioun of thin Astrelabie is this, I mene as in
this cas: - First it is divided in 4 plages principalis with the lyne that
goth from est to west; and than with another lyne that goth fro south to
north; than is it divided in smale parties of azymutz, as est, and est by
south, where as is the first azymut above the est lyne; and so furth fro
partie to partie til that thou come ageyn unto the est lyne. Thus maist
thou understonde also the cenyth of eny sterre, in which partie he riseth.
32. To knowe in which partie of the firmament is the conjunccyoun.
Considere the tyme of the conjunccyoun by the kalender, as thus: - Loke
hou many houres thilke conjunccioun is fro the midday of the day
precedent, as shewith by the canon of thy kalender. Rekene than thilke
nombre of houres in the bordure of thin Astrelabie, as thou art wont to do
in knowyng of the houres of the day or of the nyght, and ley thy label
over the degre of the sonne, and than wol the point of thy label sitte
upon the houre of the conjunccioun. Loke than in which azymut the degre of
thy sonne sittith, and in that partie of the firmament is the conjunccioun.
33. To knowe the cenyth of the altitude of the sonne.
This is no more to seyn but eny tyme of the day tak the altitude of the
sonne, and by the azymut in which he stondith maist thou seen in which
partie of the firmament he is. And in the same wise maist thou seen by
night, of eny sterre, whether the sterre sitte est or west, or north or
south, or eny partie bitwene, after the name of the azimut in which the
34. To knowe sothly the degre of the longitude of the mone, or of
eny planete that hath no latitude for the tyme fro the ecliptik lyne.
Tak the altitude of the mone, and rekne thy altitude up among thyn
almykanteras on which syde that the mone stondith, and set there a prikke.
Tak than anon-right upon the mones syde the altitude of eny sterre fix
which that thou knowist, and set his centre upon his altitude among thyn
almykanteras there the sterre is founde. Wayte than which degre of the
zodiak touchith the prykke of the altitude of the mone, and tak there the
degre in which the mone stondith. This conclusioun is verrey soth, yf the
sterres in thin Astrelabie stonden after the trouthe. Comoun tretes of the
Astrelabie ne maken non excepcioun whether the mone have latitude or noon,
ne on wheyther syde of the mone the altitude of the sterre fixe be taken.
And nota that yf the mone shewe a himself by light of day, than
maist thou worche this same conclusioun by the sonne, as wel as by the
35. This is the worchynge of the conclusioun to knowe yf that eny
planete be direct or retrograd.
Tak the altitude of any sterre that is clepid a planete, and note it
wel; and tak eke anon the altitude of any sterre fix that thou knowist,
and note it wel also. Com than ageyn the thridde or the fourthe nyght next
folewing, for than shalt thou perceyve wel the moeving of a planete,
whether so he moeve forward or bakward. Awayte wel than whan that thy
sterre fixe is in the same altitude that she was whan thou toke hir firste
altitude. And tak than eft-sones the altitude of the forseide planete and
note it wel; for truste wel yf so be that the planete be on the right syde
of the meridional lyne, so that his secunde altitude be lasse than hys
first altitude was, than is the planete direct; and yf he be on the west
syde in that condicioun, than is he retrograd. And yf so be that this
planete be upon the est side whan his altitude is ytaken, so that his
secunde altitude be more than his first altitude, than is he retrograd.
And if he be on the west syde, than is he direct. But the contrarie of
these parties is of the cours of the mone; for certis the mone moeveth the
contrarie from othre planetes as in hir epicicle, but in noon othir manere.
36. The conclusioun of equaciouns of houses after the Astrelabie.
Set the begynnyng of the degre that ascendith upon the ende of the 8
houre inequal; than wol the begynnyng of the 2 hous sitte upon the lyne of
mydnight. Remeve than the degre that ascendith, and set him on the ende of
the 10 houre inequal, and than wol the begynnyng of the 3 hous sitte up on
the mydnight lyne. Bring up ageyn the same degre that ascended first, and
set him upon the est orisonte, and than wol the begynnyng of the 4 hous
sitte upon the lyne of mydnight. Tak than the nader of the degre that
first ascendid, and set him in the ende of the 2 houre inequal; and than
wol the begynnyng of the 5 hous sitte upon the Iyne of mydnight. Set than
the nader of the ascendent in the ende of the 4 houre inequal, and than
wol the begynnyng of the 6 hous sitte on the mydnight lyne. The begynnyng
of the 7 hous is nader of the ascendent, and the begynnyng of the 8 hous
is nader of the 2 hous, and the begynnyng of the 9 hous is nader of the 3,
and the begynnyng of the 10 hous is nader of the 4, and the begynnyng of
the 11 hous is nader of the 5, and the begynnyng of the 12 hous is nader
of the 6.
37. Another maner of equaciouns of houses by the Astrelabie.
Tak thin ascendent, and than hast thou thy 4 angles; for wel thou wost
that the opposit of thin ascendent, that is to seyn, the begynnyng of the
7 hous, sitt upon the west orisonte, and the begynnyng of the hous sitt
upon the lyne meridional, and his opposyt upon the lyne of mydnight. Than
ley thy label over the degre that ascendith, and rekne fro the point of
thy label alle the degrees in the bordure tyl thou come to the meridional
lyne; and departe alle thilke degrees in 3 evene parties, and take there
the evene equacions of 3 houses; for ley thy label over everich of these 3
parties, and than maist thou se by thy label, lith in the zodiak, the
begynnyng of everich of these same houses fro the ascendent; that is to
seyn the begynnyng of the 12 hous next above thin ascendent, the begynnyng
of the 11 hous, and than the 10 upon the meridional lyne, as I first seide.
The same wise worch thou fro the ascendent doun to the lyne of mydnyght,
and thus hast thou othre 3 houses; that is to seyn, the begynnyng of the
2, and the 3, and the 4 hous. Than is the nader of these 3 houses the
begynnyng of the 3 houses that folewen.
38. To fynde the lyne meridional to dwelle fix in eny certeyn place.
Tak a round plate of metal; for werpyng, the brodder the better; and
make there upon a just compas a lite within the bordure. And ley this
rounde plate upon an evene ground, or on an evene ston, or on an evene
stok fix in the ground; and ley it evene by a level. And in the centre of
the compas styke an evene pyn, or a wyr, upright, the smaller the better;
set thy pyn by a plom-rule evene upright, and let this pyn be no lenger
than a quarter of the dyametre of thy compas, fro the centre amiddes. And
wayte bisely aboute 10 or 11 of the clokke, whan the sonne shineth, whan
the shadewe of the pyn entrith enythyng within the cercle of thy compas an
heer-mele- and marke there a pricke with inke. Abid than stille waityng on
the sonne til after 1 of the clokke, til that the shadwe of the wyr, or of
the pyn, passe enything out of the cercle of the compas, be it nevere so
lyte, and set there another pricke of ynke. Tak than a compas, and mesure
evene the myddel bitwixe bothe prickes, and set there a prikke. Tak me
than a rule and draw a strike evene a-lyne, fro the pyn unto the middel
prikke- and tak there thi lyne mer