18. The 'centre' of the star is the technical name for the extremity of the metal tongue representing it. The 'degree in which the star standeth' is considered to be that degree of the zodiac which souths along with it. Thus Sirius or Alhabor has its true longitude nearly equal to that of 12° of Cancer, but, as it souths with the 9th degree, it would be said to stand in that degree. This may serve for an example; but it must be remembered that its longitude was different in the time of Chaucer. 19. Also it rises with the 19th degree of Leo, as it is at some distance from the zodiac in latitude. The same 'marvellous arising in a strange sign' is hardly because of the latitude being north or south from the _equinoctial_, but rather because it is north or south of the _ecliptic_. For example, Regulus ([alpha] Leonis) is on the ecliptic, and of course rises with that very degree in which it is. Hence the reading _equinoctial_ leaves the case in doubt, and we find a more correct statement just below, where we have 'whan they have no latitude fro the ecliptik lyne.' At all places, however, upon the earth's equator, the stars will rise with the degrees of the zodiac in which they stand.] 20. Here the disc (fig. 5) is supposed to be placed beneath the Rete (fig. 2). The proposition merely tells us that the difference between the meridian altitudes of the given degree of the zodiac and of the 1st point of Aries is the _declination_ of that degree, which follows from the very definition of the term. There is hardly any necessity for setting the second prick, as it is sufficiently marked by being the point where the equinoctial circle crosses the south line. If the given degree lie _outside_ this circle, the declination is _south;_ if _inside_, it is _north_. 21. In fig. 5, the almicanteras, if accurately drawn, ought to shew as many degrees between the south point of the equinoctial circle and the zenith as are equal to the latitude of the place for which they are described. The number of degrees from the pole to the northern point of the _horizon obliquus_ is of course the same. The latitude of the place for which the disc is constructed is thus determined by inspection. 22. In the _first_ place where '_orisonte_' occurs, it means the _South_ point of the horizon; in the _second_ place, the _North_ point. By referring to fig. 13, Plate V, it is clear that the arc [Aries]S, representing the distance between the equinoctial and the S. point, is equal to the arc ZP, which measures the distance from the pole to the zenith; since PO[Aries] and ZOS are both right angles. Hence also Chaucer's second statement, that the arcs PN and [Aries]Z are equal. In his numerical example, PN is 51° 50'; and therefore ZP is the complement, or 38° 10'. So also [Aries]Z is 51° 50'; and [Aries]S is 38° 10'. Briefly, [Aries]Z measures the latitude.