A Treatise on the Astrolabe
Bread and Milk for Children
In Part II, §35, Chaucer gives a procedure for telling whether a planet is direct, moving with the succession of the signs, or retrograde. Compare the planet's altitude with that of a fixed star at two moments when the star stands at the same height: for a direct planet east of the meridian the altitude is less the second time, and the converse holds for a retrograde planet west of it. He warns that a change in the planet's declination can make the method fallacious.
- Author
- Geoffrey Chaucer
- Date
- c. 1391 CE
- Original language
- Middle English
- Key term
- retrograd; direct (Middle English: moving against, or with, the succession of the signs)
- Kind
- Observation record
- Planets
- General · no planet named
Editions
4 editions.
| Year | Edition | © |
|---|---|---|
| 1872 | Skeat, Walter W. (ed.). A Treatise on the Astrolabe; Addressed to His Son Lowys. London: Early English Text Society (Chaucer Society), 1872. | PD |
| 1894 | Skeat, Walter W. (ed.). The Complete Works of Geoffrey Chaucer, vol. 3. Oxford: Clarendon Press, 1894. | PD |
| 2002 | Eisner, Sigmund (ed.). A Variorum Edition of the Works of Geoffrey Chaucer, Vol. VI: Prose Treatise, Part One: A Treatise on the Astrolabe. Norman: University of Oklahoma Press, 2002. | © |
| 1872 | W. W. Skeat (ed.), A Treatise on the Astrolabe (London: Chaucer Society / Early English Text Society, 1872) | PD |
Read it
One digitised copy.
- Chaucer's Works, vol. 3, ed. Skeat (1894/1900), with the Treatise on the AstrolabeProject GutenbergPDOpen ↗Archived copy
Copies stay with their holders; every link opens their site. Licence: PD public domain · CC BY · CC BY-SA · © rights reserved · ? not stated.
Myths we don’t repeat
Checked, and left out.
- Myth 01
Not proven to be the first use of 'retrograde' in English: it is among the earliest attestations, late 14th century.
References
Also on the Asia, Islam and medieval Europe shelf
| Date | Source | Planets | Kind |
|---|---|---|---|
| c. 6th century CE | Bṛhat Saṃhitā, ch. 6: the course of MarsVarāhamihiraAstrological | Ma | Astrological |
| c. 900 CE (observations 877–918) | al-Zīj al-Ṣābiʾal-BattānīMath. astronomy | Me Ve Ma Ju Sa | Math. astronomy |
| c. 1025–1028 CE | Doubts concerning PtolemyIbn al-HaythamTheory / model | General | Theory / model |
| 13th century CE (al-ʿUrḍī d. 1266) | Treatise on planetary retrograde motionMuʾayyad al-Dīn al-ʿUrḍī (attributed)Theory / model | Me Ve Ma Ju Sa | Theory / model |
| 1261–1264 CE | Theorica planetarumCampanus of NovaraTheory / model | Me Ve Ma Ju Sa | Theory / model |
| 14th century CE (author d. 1375/6) | Nihāyat al-sūlIbn al-ShāṭirTheory / model | Me Ve Ma Ju Sa | Theory / model |