thy figure of 8; than loke how moche space of feet is be-tween thee
and the tour, and multiplye that be 12, and whan thou hast multiplied
it, than divyde it be the same nombre of 8, and kepe the residue; and
5
adde therto up to thyn eye to the residue, and that shal be the verry
heyght of the tour. And thus mayst thou werke on the same wyse, fro
1 to 12.
[41b.] Umbra Recta.
An-other maner of werking upon the same syde. Loke upon which
poynt thy rewle falleth whan thou seest the top of the tour thorow two