17. _assensiouns in the righte cercle._ This exactly answers to our modern 'right ascension.' We hence obtain the true origin of the phrase. 'Right ascension' was, originally, the ascension of stars at places situate _on the equator_, and was most conveniently measured along the equatorial circle, by observation of the times of transit of the various stars across the meridian. In other latitudes, the ascension of every degree of the _zodiac_ could be easily tabulated by observing what degree of the equator came to the meridian with the said degree of the zodiac; see l. 20. It hence appears that, whilst persisting in using 'longitudes' and reckoning along the zodiac, the ancients were obliged, in practice, to refer the degrees of longitude to the equator. The modern method of recognizing this necessity, and registering right ascensions as of more importance than longitudes, is a great improvement. The ancients were restrained from it by their unnecessary reverence for the zodiac. Cf. Ptolemy's Almagest, lib. i. c. xiii. § 29. Chaucer omits to say that the experiment should be made when the sun is very nearly on the meridian. Otherwise, the confusion of the azimuth with the hour-angle might cause a considerable error. § 30. 3. That the phrase 'wey of the sonne' really means the sun's apparent _diurnal_ course in this conclusion, may be further seen by consulting the Latin of Messahala. Cf. the Critical Note on p. 236. § 31. In my footnote, I have used the expression 'it does not mean, _as it should_, the zenith point.' I mean--'as, according to our modern ideas, it should';--for the derivation of _zenith_ shews that the meaning used in this proposition is the older meaning of the two. See note above to i. 19. 7 (p. 357). 6. _24 parties._ These 24 parts were suggested by the 24 hours of the day. The '32 parts' used by 'shipmen' are due to the continual halving of angles. Thus, the four cardinal points have points half-way between them, making eight points; between which, we can insert eight more, making sixteen; and between these, sixteen more, making thirty-two. Hence the 32 points of the compass. § 33. 5. We should probably insert _or south_ after the word _north_. Such an insertion is authorised by MSS. B. and C. § 34. 3. That 'upon the mones syde' means nearly in the same azimuth as the moon, is apparent from l. 11 below, where Chaucer says that some treatises make no exception even if the star is _not_ quite in the same azimuth. This was certainly a rough mode of observation. § 35. 9. _right side_, East side. See i. 6. 1 (p. 179).