Footnote 23
Part I, §21.  In fig. 2, Plate II, the Rete is shewn as it appears when dropped into the depression in the front of the instrument.  The shape of it varied much, and another drawing of one (copies from Camb. Univ. MS. li. 3. 3, fol. 66b is given in fig. 9, Plate IV.  The positions of the stars are marked by the extreme points of the metal tongues.  Fig. 2 is taken from the figures in the Cambridge MSS., but the positions of the stars have been corrected by the list of latitudes and longitudes given by Stöffler, whom I have followed, not because he is correct, but because he probably represents their positions as they were supposed to be in Chaucer's time very nearly indeed.  There was not room to inscribe the names of all the stars on the Rete, and to have written them on the plate below would have conveyed a false impression.  A list of the stars marked in fig. 2 is given in the note to § 21, 1.4.  The Ecliptic is the circle which crosses the Equinoctial at its East and West points (fig. 2).  In Chaucer's description of the zodiac, carefully note the distinction between the Zodiac of the Astrolabe and the Zodiac of Heaven.  The former is only six degrees broad, and shews only the northern half of the heavenly zodiac, the breadth of which is imagined to be 12 degrees.  Chaucer's zodiac only shewed every other degree in the divisions round its border.  This border is divided by help of a table of right ascensions of the various degrees of the ecliptic, which is by no means easily done.  See Note on 1.4 of this section.  I may add that the Rete is also called Aranea or Volvellum; in Arabic, Al'ancebut (the spider).