Footnote 48
Part II, §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 tS, 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 POt and ZOS are both right angles.  Hence also Chaucer's second statement, that the arcs PN and tZ are equal.  In his numerical example, PN is 51° 50'; and tS is 38° 10'.  Briefly, tZ measures the latitude.