Treatise on The Astrolabe : addressed to his son Lowys / by Geoffrey Chaucer ; edited from the earliest MSS. by Walter W. Skeat

Title

Treatise on The Astrolabe : addressed to his son Lowys / by Geoffrey Chaucer ; edited from the earliest MSS. by Walter W. Skeat

Author

Chaucer, Geoffrey, d. 1400

Editor

Skeat, Walter W. (Walter William), 1835-1912

Publication

London: N. Trübner & Co.

1872

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Link to this Item

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Cite this Item

"Treatise on The Astrolabe : addressed to his son Lowys / by Geoffrey Chaucer ; edited from the earliest MSS. by Walter W. Skeat." In the digital collection Corpus of Middle English Prose and Verse. https://name.umdl.umich.edu/ChaucerAstr. University of Michigan Library Digital Collections. Accessed May 12, 2025. content_copy

Contents

• Tractatus de Conclusionibus Astrolabii.
• Her by-gynneth the descripcion of the Astrelabie.
  • 1.
  • 2.
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  • 23.
• Her bygynnen the conclusions of the Astrelabie.
  • 1. To fynde the degree in which the sonne is day by day, after hir cours a-bowte.
  • 2. To knowe the altitude of the sonne, or of othre celestial bodies.
  • 3. To knowe euery tyme of the day by liht of the sonne, & euery tyme of the nyht by the sterres fixe, & eke to knowe by nyht or by day the degree of any signe þat assendith on the est Orisonte, which þat is cleped communly the assendent or elles oruscupum.
  • 4. Special declaracion of the assendent.
  • 5. To knowe the verrey equacioun of the degree of the sonne, yif so be þat it falle by-twixe thin Almykanteras.
  • 6. To knowe the spring of the dawyng & the ende of the euenyng, the which ben called the two crepusculus :
  • 7. To knowe the arch of the day, that some folk kallen the day artificial, from the sonne arisyng til hit go to rest[e].
  • 8. To turn̄ the howres in-equales in howres equales.
  • 9. To knowe the quantite of the day vulgare, that is to seyen, from spring of the day vn-to verrey nyht.
  • 10. To knowe the quantite of howres in-equales by day.
  • 11. To knowe the quantite of howres equales.
  • 12. Special declarcioun of the howres of planetes.
  • 13. To knowe the altitude of the sonne in Middes of the day, that is cleped the altitude Meridian.
  • 14. To knowe the degree of the sonne by thy riet, for a maner curiosite, &c.
  • 15. To know which day is lik to wych day as of lengthe, &c.
  • 16.This chapitre is a Maner declaracioun to conclusiouns þat folwen.
  • 17. To knowe the verrey degree of any maner sterre straunge or vnstraunge after his longitude, thow he be indeterminat in thin astralabie; sothly to the trowthe, thus he shal be knowe.
  • 18. To knowe the degrees of the longitudes of fixe sterres after þat they ben determinat in thin astralabie, yif so be þat they ben trewly set.
  • 19. To knowe with which degree of the zodiak any sterre fixe in thin Astrelabie arisith vp-on the est Orisonte, Al-they [h]is dwellyng be in a-nother signe.
  • 20.To knowe the declinacioun of any degree in the zodiak fro the equinoxial cercle, &c.
  • 21. To knowe for what latitude in any regioun the Almikanteras of any table ben compowned.
  • 22. To knowe in special the latitude of owre countray, I mene after the latitude of Oxenford, & the heyhte of owre pol.
  • 23. To proue euidently the latitude of any place in a Regioun, by the preue of the heyhte of the pol Artik in þat same place.
  • 24. Another conclusioun to proue the heyhte of the pool Artik fro the orisonte.
  • 25. A-nother conclusioun to proue the latitude of the Regioun, &c.
  • 26. Declaracioun of the assensioun of signes, &c.
  • 27.This is the conclusioun to knowe the Assenciouns of signes in the riht cercle, þat is, circulus directus, &c.
  • 28.To knowe the assencions of signes in the Embelif cercle in euery regioun, I Mene, in circulo obliquo.
  • 29.To knowe Iustly the 4 quarters of the world, as est, west, north, & sowth.
  • 30. To knowe the Altitude of planetes fro the wey of the sonne, whether so they be north or sowth fro the forseide wey.
  • 31. To knowe the senyth of the arysing of the sonne, this is to seyn, the partie of the Orisonte in which þat the sonne arisith.
  • 32. To knowe in which partie of the firmament is the coniunccioun.
  • 33. To knowe the senyth of the Altitude of the sonne, &c.
  • 34. To knowe sothly the degree of the longitude of the mone, or of any planete þat hath no latitude for the tyme fro the Ecliptik lyne.
  • 35. This is the workinge of the conclusioun, to knowe yif þat any planete be directe or retrograde.
  • 36. The conclusiouns of equaciouns of howses, after the astralabie, &c.
  • 37. A-nother manere of equaciouns of howses by the Astrelabie.
  • 38. To fynde the lyne Merydional to dwelle fix in any certein place.
  • 39. Descripcion of the Meridional lyne, of longitudes, & latitudes of Citees and townes from on to a-no[t]her of clymatz.
  • 40.To knowe with which degree of the zodiak þat any planete Assendith on the Orisonte, wheyther so that his latitude be north or sowth.
  • 41. Vmbra Recta.
  • 42. Vmbra Versa.
  • 43. Vmbra [Recta].
  • 44. Another maner conclusion, to knowe the mene mote & þe argumentis of any planete. To know the mene mote & the argumentis of euery planete fro ȝere to ȝere, from day to day, from owre to owre, And from smale fraccionis infinite.
  • 45. Another manere to knowe the mene mote.
  • 4la. Vmbra Recta.
  • 41b. Vmbra Recta.
  • 42a. Vmbra Versa.
  • 43a. Ad cognoscendum altitudinem alicuius rei per vmbram [rectam].
  • 42b. Per vmbram versam.
  • 46. For to knowe at what houre of þe day, or of the night, shal be Flode or ebbe.