To knowe the arch of the day, that some folk
callen the day
artificiall, fro sonne arisyng tyl it go to reste.
Set the degre of thi sonne upon thin est orisonte, and ley thy
label on the degre of the sonne, and at the point of thy label
in the bordure set a pricke. Turne than thy riet aboute tyl the
degre of the sonne sitte upon the west orisonte, and ley thy
label upon the same degre of the sonne, and at the poynt of thy
label set another pricke. Rekne than the quantite of tyme in the
bordure bitwixe bothe prickes, and tak there thyn arch of the
day. The remenaunt of the bordure under the orisonte is the arch
of the nyght. Thus maist thou rekne bothe arches, or every
porcioun, of whether that the liketh. And by this manere of
worching maist thou se how longe that eny sterre fix dwelleth
above the erthe, fro tyme that he riseth til he go to reste. But
the day naturall, that is to seyn 24 hours, is the revolucioun
of the equinoxial with as muche partie of the zodiak as the sonne
of his propre moeving passith in the mene while.
