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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| A Treatise on the Astrolabe | 1/2 | https://en.wikipedia.org/wiki/A_Treatise_on_the_Astrolabe | reference | science, encyclopedia | 2026-05-05T16:11:41.698992+00:00 | kb-cron |
A Treatise on the Astrolabe is a medieval instruction manual on the astrolabe, completed by Geoffrey Chaucer in 1391. Notable as technical prose from a writer better known for poetry, it describes both the form and the proper use of the instrument. It was written in Middle English rather than the more typical Latin. The treatise is dedicated to Chaucer's son Lowys (Lewis), who was ten during its composition.
== Significance == The Treatise is considered the 'oldest work in English written upon an elaborate scientific instrument'. It is admired for its clarity in explaining difficult concepts, although modern readers lacking an actual astrolabe may find these descriptions difficult to understand. Robinson believes that it indicates that had Chaucer written more freely composed prose it would have been superior to his translations of Boethius and Renaut de Louhans. Chaucer’s exact source is undetermined, but most of his ‘conclusions’ go back, directly or indirectly, to Compositio et Operatio Astrolabii, a Latin translation of Messahala's Arabic treatise of the 8th century. His description of the instrument amplifies Messahala’s, and Chaucer’s indebtedness to Messahala was recognised by John Selden and established by Walter William Skeat. Mark Harvey Liddell held Chaucer drew on De Sphaera of John de Sacrobosco for the substance of his astronomical definitions and descriptions, but the non-correspondence in language suggests the probable use of an alternative compilation. A collotype facsimile of the second part of the Latin text of Messahala (the portion which is parallel to Chaucer's) is found in Skeat’s Treatise On The Astrolabe. and in Gunther's Chaucer and Messahalla on the Astrolabe. Paul Kunitzsch argued that the treatise on the astrolabe long attributed to Messahala was in fact written by Ibn al-Saffar.
=== Language === The work is written in the free-flowing Middle English of that time (1391). Chaucer explains this departure from the norm thus:
"This treatis, ..., wol I shewe the ... in Englissh, for Latyn ne canst thou yit but small" Chaucer proceeds to labour the point somewhat:
"Grekes ... in Grek; and to Arabiens in Arabik, and to Jewes in Ebrew, and to Latyn folk in Latyn; whiche Latyn folk had hem [conclusions] first out of othere dyverse languages, and writen hem in her owne tunge, that is to seyn, in Latyn.". He continues to explain that it easier for a child to understand things in his own language than struggle with unfamiliar grammar, a commonplace idea today but radical in the fourteenth century. Finally, he appeals to Royalty. Philippa Roet, Chaucer's wife was a lady-in-waiting to Philippa of Hainault, Edward III's queen. She was also a sister to Katherine Swynford, John of Gaunt's wife. Chaucer's appeal is an early version of the phrase "the King's English":
"And preie God save the King, that is lord of this language, ..."
=== Manuscripts === Skeat identifies 22 manuscripts of varying quality. The best he labels A, B and C which are MS. Dd. 3.53 (part 2) in the Cambridge University Library, MS. E Museo 54 in the Bodleian Library and MS. Rawlinson, Misc. 1262 also in the Bodleian. A and B were apparently written by the same scribe, but A has been corrected by another hand. Skeat observes that the errors are just those described in "Chaucers Wordes unto Adam, His Owne Scriveyn":
"So ofte a-daye I mot thy werk renewe, "It to correcte and eek to rubbe and scrape; "And al is thorough thy negligence and rape." A has indeed been rubbed and scraped then corrected by another hand. This latter scribe Skeat believes to be a better writer than the first. To this second writer was the insertion of diagrams entrusted. A and B were apparently written in London about the year 1400, that is some 9 years after the original composition. Manuscript C is also early, perhaps 1420 and closely agrees with A.
== Audience == Chaucer opens with the words "Lyte Lowys my sone". In the past a question arose whether the Lowys was Chaucer's son or some other child he was in close contact with. Kittredge suggested that it could be Lewis Clifford, a son of a friend and possible a godson of Chaucer's. As evidence he advanced that Lewis Clifford died in October 1391, the year of the composition, which could explain its abandonment. Robinson reports though the finding of a document by Professor Manly "recently" (to 1957) which links one Lewis Chaucer with Geoffrey's eldest child Thomas Chaucer. The likelihood therefore is that the dedication can be taken at face value. Chaucer had an eye to the wider public as well. In the prologue he says:
Now wol I preie mekely every discret persone that redith or herith this litel tretys..."
== Structure == The work was planned to have an introduction and five sections:
A description of the astrolabe A rudimentary course in using the instrument Various tables of longitudes, latitudes, declinations, etc. A "theorike" (theory) of the motion of the celestial bodies, in particular a table showing the "very moving of the moon" 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 astronomy. Part 1 is complete and extant. Part 2 is also extant with certain caveats described below. Part 3, if it ever existed, is not extant as part of the Treatise. Part 4 was, in the opinion of Skeat, probably never written. Part 5 also was probably never written which Skeat approves of. Indeed, he draws attention to Chaucer's comment at the end of conclusion 4:
"Natheles these ben observaunces of judicial matere and rytes of payens, in whiche my spirit hath no feith, no knowing of her horoscopum."
=== Part 1 ===