A Treatise on the Astrolabe
Geoffrey Chaucer lived appr. 1340-1400. "A Treatise on
the Astrolabe" was once believed to have been written for
a son of Chaucer's. "Lyte Lowys" (Little Lewis) is,
however, presumably the son of a friend, Lewis Clifford. The boy
probably died in 1391, which might explain why this work is unfinished.
The text is the oldest known "technical manual" in the
English language, and it was compiled from different foreign sources.
The beginning is, however, Chaucer's very own.
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 envie.
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 midnyght.
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 firmament.
6. 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.
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 another.
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 Astralabie.
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- ward.
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 every regioun.
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
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 aboute.
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
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 experience.
2. To knowe the altitude of the sonne or of othre celestial
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 sterres.
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
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
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
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,
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
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 declaracioun?
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 contrarie.
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 this world.
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 another signe.
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
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 equinoxiall cercle.
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 equinoxiall.
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 the orisonte.
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
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
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 sterre stondith.
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
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 fixe sterre.
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
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 heved. And it is cleped the lyne meridional,
for in what place that eny man ys at any tyme of the yer, whan
that the sonne, by mevynge of the firmament, cometh to his verrey
meridian place, than is it verrey mydday, that we clepen oure
non, as to thilke man. And therefore is it clepid the Iyne of
mydday. And nota that evermore of eny 2 cytes or 2 townes, of
which that oo town approchith more toward the est than doth that
othir town, truste wel that thilke townes han diverse meridians.
Nota also that the arch of the equinoxial that is contened or
bownded bitwixe the 2 meridians is clepid the longitude of the
toun. And yf so be that two townes have ilike meridian or oon
meridian, than is the distaunce of hem both ilike fer fro the
est, and the contrarie; and in this manere thei change not her
meridian. But sothly thei chaungen her almykanteras, for the enhaunsyng
of the pool and the distance of the sonne.
The longitude of a climat is a lyne ymagined fro est to west ilike
distant fro the equinoxiall. And the latitude of a climat may
be cleped the space of the erthe fro the begynnyng of the first
clymat unto the verrey ende of the same clymat evene direct ageyns
the pool artyke. Thus sayn somme auctours; and somme of hem sayn
that yf men clepe the latitude of a cuntrey the arch meridian
that is contened or intercept bitwix the cenyth and the equinoxial,
than say they that the distance fro the equinoxial unto the ende
of a climat evene ageynst the pool artik is the latitude of a
40. To knowe with which degre of the zodiak that eny planete
ascendith on the orisonte, whether so that his latitude be north
Know by thin almenak the degre of the ecliptik of eny signe in
which that the planete is rekned for to be, and that is clepid
the degre of his longitude. And know also the degre of his latitude
fro the ecliptik north or south. And by these ensamples folewynge
in speciall maist thou worche forsothe in every signe of the zodiak:
The degree of the longitude per-aventure of Venus or of another
planete was 6 of Capricorne, and the latitude of hir was northward
2 degrees fro the ecliptik lyne. Than tok I a subtil compas and
clepid that oo point of my compas . and that other point F. Than
tok I the point of A and sette it in the ecliptik ]yne in my zodiak
in the degre of the longitu(lc of Venus, that is to seyn, in the
6 degre of Capricorne; and than sette I the point of F upward
in the same signe by cause that latitude was north upon the latitude
of Venus, that is to seyn, in the 6 degre fro the heved of Capricorne;
and thus have I 2 degrees bitwixe my two prickes. Than leide I
down softly my compas, and sette the degre of the longitude upon
the orisonte; tho tok I and waxed my label in manere of a peire
tables to receyve distinctly the prickes of my compas. Tho tok
I thys forseide label, and leyde it fix over the degre of my longitude;
tho tok I up my compas and sette the point of A in the wax on
my label, as evene as I koude gesse, over the ecliptik lyne in
the ende of the longitude, and sette the point of F endelong in
my label upon the space of the latitude, inward and over the zodiak,
that is to seyn northward fro the ecliptik. Than leide I doun
my compas, and loked wel in the wey upon the prickes of A and
of F; tho turned I my ryet til that the pricke of F satt upon
the orisonte; than saw I wel that the body of Venus in hir latitude
of 2 degrees septemtrionals ascendid, in the ende of the 6 degre,
in the heved of Capricorne.
And nota that in this manere maist thou worche with any
latitude septem- trional in alle signes. But sothly the latitude
meridional of a planete in Capricorne ne may not be take by cause
of the litel space bitwixe the ecliptyk and the bordure of the
Astrelabie; but sothely in all othre signes it may.
2 pars hujus conclusio.
Also the degre peraventure of Jupiter, or of another planete,
was in the first degre of Piscis in longitude, and his latitude
was 2 degrees meridional; tho tok I the point of A and sette it
in the first degre of Piscis on the ecliptik; and than sette I
the point of F dounward in the same signe by cause that the latitude
was south 2 degres, that is to seyn, fro the heved of Piscis;
and thus have 2 degres bitwexe bothe 66 prikkes. Than sette I
the degre of the longitude upon the orisonte; tho tok I my label,
and leide it fix upon the degre of the longitude; tho sette I
the point of A on my label evene over the ecliptik lyne in the
ende of the degre of the longitude, and sette the point of F endlong
in my label the space of 2 degres of the latitude outward fro
the zodiak (this is to seyn southward fro the ecliptik toward
the bor- dure), and turned my riet til that the pricke of F saat
upon the orisonte. Than say I wel that the body of Jupiter in
his latitude of 2 degres meridional ascendid with 8 degres of
Piscis in horoscopo. And in this manere maist thou worche with
any latitude meridional, as I first seide, save in Capricorne.
And yf thou wilt pleye this craft with the arisyng of the mone,
loke thou rekne wel hir cours houre off by houre, for she ne dwellith
not in a degre of hir longitude but litel while, as thow wel knowist.
But natheles yf thou rekne hir verrey moevyng by thy tables houre
after houre, [thou shalt do wel ynow].
41. Umbra Recta.
Yif it so be that thou wilt werke by umbra recta, and thou
may come to the bas of the tour, in this maner thou shalt werke.
Tak the altitude of the tour by bothe holes, so that thy rewle
ligge even in a poynt. Ensample as thus: I see him thorw at the
poynt of 4; than mete I the space between me and the tour, and
I finde it 20 feet; than beholde I how 4 is to 12, right so is
the space betwixe thee and the tour to the altitude of the tour.
For 4 is the thridde part of 12, so is the space between thee
and the tour the thridde part of the altitude of the tour; than
thryes 20 feet is the heyghte of the tour, with adding of thyn
owne persone to thyn eye. And this rewle is so general in umbra
recta, fro the poynt of oon to 12. And yif thy rewle falle
upon 5, than is 5 12-partyes of the heyght the space between thee
and the tour; with adding of thyn owne heyghte.
42. Umbra Versa.
Another maner of werkinge, by umbra versa. Yif so be that
thou may nat come to the bas of the tour, I see him thorw the
nombre of 1; I sette ther a prikke at my fot; than go I neer to
the tour, and I see him thorw at the poynt of 2, and there I sette
another prikke; and I beholde how 1 hath him to 12, and ther finde
I that it hath him twelfe sythes; than beholde I how 2 hath him
to 12, and thou shalt finde it sexe sythes;than thoushaltfinde
that as 12 above 6 is the numbre of 6, right so is the space between
thy two prikkes the space of 6 tymes thyn altitude. And note,
that at the ferste altitude of 1, thou settest a prikke; and afterward,
whan thou seest him at 2, ther thou settest another prikke; than
thou findest between two prikkys 60 feet; than thou shalt finde
that 10 is the 6-party of 60. And then is 10 feet the altitude
of the tour. For other poyntis, yif it fille in umbra versa, as thus: I sette caas it fill upon 2, and at the secunde upon
3; than schalt thou finde that 2 is 6 partyes of 12; and 3 is
4 partyes of 12; than passeth 6 4, by nombre of 2; so is the space
between two prikkes twyes the heyghte of the tour. And yif the
differens were thryes, than shulde it be three tymes; and thus
mayst thou werke fro 2 to 12; and yif it be 4, 4 tymes; or 5,
5 tymes; et sic de ceteris.
43. Umbra Recta.
Another maner of wyrking, by umbra recta. Yif it so be
that thou mayst nat come to the baas of the tour, in this maner
thou schalt werke. Set thy rewle upon 1 till thou see the altitude,
and set at thy foot a prikke. Than set thy rewle upon 2, and behold
what is the differense between 1 and 2, and thou shalt finde that
it is 1. Than mete the space between two prikkes, and that is
the 12 partie of the altitude of the tour. And yif ther were 2,
it were the 6 partye; and yif ther were 3, the 4 partye; et
sic deinceps. And note, yif it were 5, it were the 5 party
of 12; and 7, 7 party of 12; and note, at the altitude of thy
onclusioun, adde the stature of thyn heyghte to thyn eye.
* * * * * * *
44. Another maner conclusion, to knowe the mene mote and the
argumentis of any planete. To know the mene mote and the argumentis
of every planete fro yere to yere, from day to day, from houre
to houre, and from smale fraccionis infinite.
In this maner shalt thou worche; consider thy rote first, the
whiche is made the beginning of the tables fro the yer of oure
Lord 1397, and enter hit into thy slate for the laste meridie
of December- and than consider the yer of oure Lord, what is the
date, and behold whether thy date be more or lasse than the yer
1397. And yf hit so be that hit be more, loke how many yeres hit
passeth, and with so many enter into thy tables in the first Iyne
theras is writen anni collecti et expansi. And loke where
the same planet is writen in the hed of thy table, and than loke
what thou findest in direct of the same yer of oure Lord which
is passid, be hit 8, or 9, or 10, or what nombre that evere it
be, til the tyme that thou come to 20, or 40, or 60. And that
thou findest in direct wryt in thy slate under thy rote, and adde
hit togeder, and that is thy mene mote, for the laste meridian
of the December, for the same yer which that thou hast purposed.
And if hit so be that hit passe 20, consider wel that fro 1 to
20 ben anni expansi, and fro 20 to 3000 ben anni collecti; and if thy nomber passe 20, than tak that thou findest in direct
of 20, and if hit be more, as 6 or 18, than tak that thou findest
in direct thereof, that is to sayen, signes, degrees, minutes,
and secoundes, and adde togedere unto thy rote; and thus to make
rotes. And note that if hit so be that the yer of oure Lord be
lasse than the rote, which is the yer of oure Lord 1397, than
shalt thou wryte in the same wyse furst thy rote in thy slate,
and after enter into thy table in the same yer that be lasse,
as I taught before; and than consider how many signes, degrees,
minutes, and secoundes thyn entringe conteyneth. And so be that
thebe 2 entrees, than adde hem togeder, anafter withdraw hem from
the rote, the yer of oure Lord 1397; and the residue that leveth
is thy mene mote for the laste meridie of December, the whiche
thou hast purposed; and if hit so be that thou wolt weten thy
mene mote for any day, or for any fraccioun of day, in this maner
thou shalt worche. Make thy rote fro the laste day of December
in the maner as I have taught, and afterward behold how many monethes,
dayes, and houres ben passid from the meridie of December, and
with that enter with the laste moneth that is ful passed, and
take that thou findest in direct of him, and wryt hit in thy slate;
and enter with as mony dayes as be more, and wryt that thou findest
in direct of the same planete that thou worchest for; and in the
same wyse in the table of houres, for houres that ben passed,
and adde alle these to thy rote; and the residue is the mene mote
for the same day and the same houre.
45. Another manere to knowe the mene mote.
Whan thou wolt make the mene mote of eny planete to be by Arsechieles
tables tak thy rote, the whiche is for the yer of oure Lord 1397;
and if so be that thy yer be passid the date, wryt that date,
and than wryt the nomber of the yeres. Than withdraw the yeres
out of the yeres that ben passed that rote. Ensampul as thus:
the yer of oure Lord 1400, I wolde witen, precise, my rote; than
wroot I furst 1400. And under that nomber I wrot a 1397; than
withdrow I the laste nomber out of that, and than fond I the residue
was 3 yer; I wiste that 3 yer was passed fro the rote, the whiche
was writen in my tables. Than afterward soghte I in my tables
the annis collectis et expansis, and among myn expanse
yeres fond I 3 yeer. Than tok I alle the signes, degrees, and
minutes, that I fond direct under the same planete that I wroghte
for, and wroot so many signes, degrees, and minutes in my slate,
and afterward added I to signes, degrees, minutes, and secoundes,
the whiche I fond in my rote the yer of oure Lord 1397; and kepte
the residue; and than had I the mene mote for the laste day of
December. And if thou woldest wete the mene mote of any planete
in March April, or May, other in any other tyme or moneth of the
yer, loke how many monethes and dayes ben passed from the laste
day of December, the yer of oure Lord 1400; and so with monethes
and dayes enter into thy table ther thou findest thy mene mote
ywriten in monethes and dayes, and tak alle the signes, degrees,
minutes, and secoundes that thou findest ywrite in direct of thy
monethes, and adde to signes, degrees, minutes, and secoundes
that thou findest with thy rote the yer of oure Lord 1400, and
the residue that leveth is the mene mote for that same day. And
note, if hit so be that thou woldest wete the mene mote in any
yer that is lasse than thy rote, withdraw the nomber of so many
yeres as hit is lasse than the yer of oure Lord a 1397, and kep
the residue; and so many yeres, monethes, and dayes enter into
thy tabels of thy mene mote. And tak alle the signes, degrees,
and minutes, and secoundes, that thou findest in direct of alle
the yeres, monethes, and dayes, and wryt hem in thy slate; and
above thilke nomber wryt the signes, degrees, minutes and secoundes,
the whiche thou findest with thy rote the yer of oure Lord a 1397;
and withdraw alle the nethere signes and degrees fro the signes
and de- grees, minutes, and secoundes of other signes with thy
rote; and thy residue that leveth is thy mene mote for that day.
46. For to knowe at what houre of the day or of the night,
shal be flod or ebbe.
First wite thou certeinly, how that haven stondeth, that thou
list to werke for; that is to say in which place of the firmament
the mone being, maketh full see. Than awayte thou redily in what
degree of the zodiak that the mone at that tyme is inne. Bring
furth than the label, and set the point therof in that same cost
that the mone maketh flod, and set thou there the degree of the
mone according with the egge of the label. Than afterward awayte
where is than the degree of the sonne, at that tyme. Remeve thou
than tlle label fro the mone, and bring and set it justly upon
the degree of the sonne. And the point of the label shal than
declare to thee, at what houre of the day or of the night shal
be flod. And there also maist thou wite by the same point of the
label, whether it be, at that same tyme, flod or ebbe, or half
flod, or quarter flod, or ebbe, or half or quarter ebbe; or ellis
at what houre it was last, or shal be next by night or by day,
thou than shalt esely knowe, &c. Furthermore, if it so be
that thou happe to worke for this matere aboute the tyme of the
conjunccioun, bring furth the degree of the mone with the label
to that coste as it is before seyd. But than thou shalt under-
stonde that thou may not bringe furth the label fro the degree
of the mone as thou dide before; for-why the sonne is than in
the same degree with the mone. And so thou may at that tyme by
the point of the label unremeved knowe the houre of the flod or
of the ebbe, as it is before seyd, &c. And evermore as thou
findest the mone passe fro the sonne, so remeve thou the label
than fro the degree of the mone, and bring it to the degree of
the sonne. And work thou than as thou dide before, &c. Or
elles know thou what houre it is that thou art inne, by thyn instrument.
Than bring thou furth fro thennes the label and ley it upon the
degree of the mone, and therby may thou wite also whan it was
flod, or whan it wol be next, be it night or day; &c.
Edition by F. N. Robinson, originally on the Origo Website in
This text is part of the Internet Medieval Source Book.
The Sourcebook is a collection of public domain and copy-permitted
texts related to medieval and Byzantine history.
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© Paul Halsall August 1997