Treatise on the Astrolabe
Encyclopedia
A Treatise on the Astrolabe is a medieval essay
on the astrolabe
by Geoffrey Chaucer
. It begins:
or, in a more modern English spelling,
According to the introduction, the work was to have five parts:
However, Chaucer only completed parts 1 and 2, plus a small collection of "Supplementary Propositions".
The Treatise is considered the oldest work in English
describing a complex scientific instrument, and is admired for its clarity in explaining difficult concepts—although since the astrolabe and related tools are no longer in common use, much of it is difficult for modern readers to understand.
The stars listed on the rim of the rete of the drawings in the Treatise are given below with their modern names:
Essay
An essay is a piece of writing which is often written from an author's personal point of view. Essays can consist of a number of elements, including: literary criticism, political manifestos, learned arguments, observations of daily life, recollections, and reflections of the author. The definition...
on the astrolabe
Astrolabe
An astrolabe is an elaborate inclinometer, historically used by astronomers, navigators, and astrologers. Its many uses include locating and predicting the positions of the Sun, Moon, planets, and stars, determining local time given local latitude and longitude, surveying, triangulation, and to...
by Geoffrey Chaucer
Geoffrey Chaucer
Geoffrey Chaucer , known as the Father of English literature, is widely considered the greatest English poet of the Middle Ages and was the first poet to have been buried in Poet's Corner of Westminster Abbey...
. It begins:
- 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 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 after 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.
or, in a more modern English spelling,
- Little Lewis my son, I perceive well by certain evidences thine ability to learn sciences touching numbers and proportionsProportionality (mathematics)In mathematics, two variable quantities are proportional if one of them is always the product of the other and a constant quantity, called the coefficient of proportionality or proportionality constant. In other words, are proportional if the ratio \tfrac yx is constant. We also say that one...
; and as well consider I thy constant prayer in special to learn the treatise of the Astrolabe. Than for as much as a philosopher saith, "He wrappth him in his friend, that condescendth to the rightful prayers of his friend", therefore have I given thee a suffisant Astrolabe as for our horizons, compounded after latitude of OxfordOxfordThe city of Oxford is the county town of Oxfordshire, England. The city, made prominent by its medieval university, has a population of just under 165,000, with 153,900 living within the district boundary. It lies about 50 miles north-west of London. The rivers Cherwell and Thames run through...
; upon which, by means of this little treatise, I purpose to teach thee a certain number of conclusions pertaining to the same instrument.
According to the introduction, the work was to have five parts:
- A description of the astrolabe
- A rudimentary course in using the instrument
- Various tables of longitudeLongitudeLongitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....
s, latitudeLatitudeIn geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
s, declinationDeclinationIn astronomy, declination is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. Declination in astronomy is comparable to geographic latitude, but projected onto the celestial sphere. Declination is measured in degrees north and...
s, etc. - A "theorike" (theoryTheoryThe English word theory was derived from a technical term in Ancient Greek philosophy. The word theoria, , meant "a looking at, viewing, beholding", and referring to contemplation or speculation, as opposed to action...
) of the motion of the celestial bodies, in particular a table showing the "very moving of the moonMoonThe Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
" - An introduction to the broader field of "astrologie," a word which at the time referred to the entire span of what we now divide into astrology and astronomyAstrology and astronomyAstrology and astronomy were archaically one and the same discipline , and were only gradually recognized as separate in Western 17th century philosophy ....
.
However, Chaucer only completed parts 1 and 2, plus a small collection of "Supplementary Propositions".
The Treatise is considered the oldest work in English
English language
English is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...
describing a complex scientific instrument, and is admired for its clarity in explaining difficult concepts—although since the astrolabe and related tools are no longer in common use, much of it is difficult for modern readers to understand.
The stars listed on the rim of the rete of the drawings in the Treatise are given below with their modern names:
| Name on Rete | Modern Designation |
|---|---|
| Alkab | Iota Aurigae |
| Alpheta | Alpha Corona Borealis |
| Alramih | Arcturus |
| Alkaid | Eta Ursae Majoris |
| K.Alasad | Alpha Leonis |
| Algomisa | Procyon |
| Alhabor | Sirius |
| Alghul | Beta Persei |
| Alnath | Beta Tauri |
| Markab | Alpha Pegasi |
| Alradif | Delta Cephei |
| Alnasir | Alpha Andromedae |
External links
- Plain-text format (with line numbering): Part 1 Part 2
- from eChaucer
- A Treatise on the Astrolabe - a verb database (language analysis, description of the astrolabe and Middle English period)