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A Treatise on the Astrolabe - Part 1
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
5tretys of the Astrelabie. Than for as moche as a
philosofre saith, "he wrappith him in his frend,
that condescendith to the rightfulle praiers of his
frend," therfore have I yeven the a suffisant Astrolabie
as for oure orizonte, compowned
10after the 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
15first 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. Another
20cause 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.
25This tretis, divided in 5 parties, wol I shewe
the under full light reules and naked wordes in
Englissh, for Latyn canst thou yit but small,
my litel sone. But natheles suffise to the these
trewe conclusions in Englissh as wel as sufficith
30to these noble clerkes Grekes these
same conclusions in Grek; and to Arabiens
in Arabik, and to Jewes in Ebrew, and to
Latyn folk in Latyn; whiche Latyn folk had
hem first out of othere dyverse langages, and
35writen 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
40leden 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 firste cause
45is 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.
50And Lowys, yf so be that I shewe the in
my lighte 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
55of 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
60not 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.
65Prima 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 oune instrument.
Secunda pars. -- The secunde partie
70shal 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
75wol 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
80of 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
85of the reverent clerkes, Frere J. Somer 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
90fourthe 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
95wel 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.
100Quinta 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
105tables 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.
Part I
Here Begynneth the descripcioun of thin Astrolabie.
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 rowme 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
hir wombe the thynne plates compowned
for diverse clymates, and thy reet shapen in
manere of a nett or of a web of a loppe.
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 to seien,
mynutes of an houre.
8.Under the compas of thilke degrees ben
writen the names of the 12 Signes: as
Aries, Taurus, Gemini, Cancer, Leo, Virgo,
Libra, Scorpio, Sagittarius, Capricornus, Aquarius,
Piscis. And the nombres of the degrees of
thoo signes be writen in augrym above, and
with longe divisiouns fro 5 to 5, dyvidid fro
the 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 somme for
her propirtees and somme by statutes of
Arabiens, somme by othre lordes of Rome.
Eke of these monthes, as liked to Julius
Cesar and to Cesar Augustus, somme were
compouned of diverse nombres of daies, as
Julie and August. Than hath Januarie 31 daies,
Februarie 28, March 31, Aprill 30, May 31,
Junius 30, Julius 31, Augustus 31, Septembre
30, Octobre 31, Novembre 30, Decembre 31.
Natheles, all though that Julius Cesar toke 2
daies out of Feverer and putte hem in his
month of Juyll, and Augustus Cesar clepid the
month of August after his name and ordeined
it of 31 daies, yit truste wel that the
sonne dwellith therfore nevere the more
ne lasse in oon signe than in another.
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 cros 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 understond wel
that degres of this bordure ben aunswering and
consentrike to the degrees of the equinoxiall,
that is dividid in the same nombre as every
othir cercle is in the highe hevene. This
same bordure is divided also with 23
lettres capitals and a small cross (+) 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 mile-wei
maken an houre. And every degre of 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 cercles, of whiche the leest is
clepid the cercle of Cancre by cause that the
heved of Cancre turnith evermo consentrik
upon the same cercle. In this heved
of Cancer is the grettist declinacioun northward
of the sonne, and therfore is he clepid
solsticium of somer; which declinacioun, after
Ptholome, is 23 degrees and 50 minutes as
wel in Cancer as in Capricorn. This signe
of Cancer is clepid the tropik of somer, of
tropos, that is to seien "ageynward." For than
beginneth the sonne to passen from us-ward.
The myddel cercle in wydnesse, of these 3,
is clepid the cercle equinoxiall, upon which
turnith evermo the hevedes of Aries and Libra.
And understond wel that evermo thys cercle
equinoxiall turnith justly from verrey est to verrey
west as I have shewed the in the speer
solide. This same cercle is clepid also
Equator, that is the weyer of the day; for
whan the sonne is in the hevedes of Aries and
Libra, than ben the dayes and the nightes ylike
of lengthe in all the world. And therfore ben
these 2 signes called the equinoxiis. And all
that moeveth withinne the hevedes of these
Aries and Libra, his moevyng is clepid northward;
and all that moevith withoute these
hevedes, his moevyng is clepid southward,
as fro the equinoxiall. Tak kep of these
latitudes north and south, and forget it nat.
By this cercle equinoxiall ben considred the
24 houres of the clokke; for evermo the arisyng
of 15 degrees of the equinoxiall makith an
houre equal of the clokke. This equinoxiall is
clepid the gurdel of the first moeving, or ellis
of the firste moevable. And note that the firste
moevyng is clepid moevyng of the firste moevable
of the 8 speer, which moeving is from
est to west, and eft ageyn into est. Also
it is clepid girdel of the firste moeving for it
departith the firste moevable, that is to seyn
the spere, in two like partyes evene distantz
fro the poles of this world.
The widest of these 3 principale cercles is
clepid the cercle of Capricorne, by cause that
the heved of Capricorne turneth evermo consentrik
upon the same cercle. In the heved of
this forseide Capricorne is the grettist declinacioun
southward of the sonne, and therfore
it is clepid the solsticium of wynter.
This signe of Capricorne is also clepid the
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 firste
cercle, is clepid the orizonte, that is to seyn,
the cercle that divideth the two emysperies,
that is, the partie of the hevene above the
erthe and the partie bynethe. These almykanteras
ben compowned by 2 and 2, all
be it so that on diverse Astrelabies somme
almykanteras ben divided by oon, and somme
by two, and somme by thre, after the quantite
of the Astrelabie. This forseide cenyth is
ymagined to ben the verrey point over the
crowne of thin heved. And also this cenyth
is the verray pool of the orizonte in every regioun.
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 divisiouns embelif,
muche like to the shap of the azemutz, that
shewen the spaces of the houres of planetes.
21.The riet of thin Astrelabie with thy zodiak,
shapen in manere of a net or of a lopweb
after the olde descripcioun, which thou maist
turnen up and doun as thiself liketh, contenith
certein nombre of 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 the smale point is
clepid the centre. And understond also that
alle the sterres sitting within the zodiak of
thin Astrelabie ben clepid sterres of the north,
for thei arise by northe the est lyne. And all the
remenaunt fixed oute of the zodiak ben clepid
sterres of the south. But I seie not that thei arisen
alle by southe the est lyne; witnesse on Aldeberan
and Algomeysa. Generaly understond this
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 this 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 lynes withoute
eny latitude. Amiddes this celestial
zodiak is ymagined a lyne which that is
clepid the ecliptik lyne, under which lyne
is evermo the wey of the sonne. Thus ben
there 6 degres of the zodiak on that oo syde
of the lyne and 6 degrees on that othir. This
zodiak is dividid in 12 principale divisiouns that
departen the 12 signes, and, for the streitnesse
of thin Astrolabie, than is every smal divisioun
in a signe departed by two degrees and two, I
mene degrees contenyng 60 mynutes. And
this forseide hevenysshe zodiak is clepid
the cercle of the signes, or the cercle of the
bestes, for "zodia" in langage of Grek sowneth
"bestes" in Latyn tunge. And in the zodiak
ben the 12 signes that han names of bestes,
or ellis for whan the sonne entrith in eny
of tho signes he takith the propirte of suche
bestes, or ellis for that the sterres that ben
ther fixed ben disposid in signes of bestes or
shape like bestes, or elles whan the planetes
ben under thilke signes thei causen us by
her influence operaciouns and effectes like
to the operaciouns of bestes.
And understond also that whan an hot planete
cometh into an hot signe, than encrescith
his hete; and yf a planete be cold, than amenusith
his coldnesse by cause of the hoote sygne.
And by thys conclusioun maist thou take ensample
in alle the signes, be thei moist or drie,
or moeble or fixe, reknyng the qualite of the
planete as I first seide. And everich of
these 12 signes hath respect to a certeyn
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 8 speer,
over-kervith the equinoxial, and he over-kervith
him ageyn in evene parties; and
that oo half declineth southward; and that
othir northward, as pleinly declarith the Tretys
of the Speer.
Than hast thou a label that is shapen like
a reule, save that it is streit and hath no plates
on either ende with holes. But with the smale
point of the forseide label shalt thou calcule
thin equaciouns in the bordure of thin Astralabie,
as by thin almury.
Thin almury is clepid the denticle of
Capricorne, or ellis the calculer. This same
almury sitt fix in the heved of Capricorne, and
it serveth of many a necessarie conclusioun in
equacions of thinges as shal be shewid.
Here endith the descripcioun of the Astrelaibe and here begynne the conclusions of the Astrelabie.

Site Updated March 31, 2011