altitude of the tour. For other poyntis, yif it fille in umbra versa,
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as thus: I sette caas it fill upon 2, and at the secunde upon 3;
than schalt thou finde that 2 is 6 partyes of 12; and 3 is 4 partyes
of 12; than passeth 6 4, by nombre of 2; so is the space between
two prikkes twyes the heyghte of the tour. And yif the differens
were thryes, than shulde it be three tymes; and thus mayst thou
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werke fro 2 to 12; and yif it be 4, 4 tymes; or 5, 5 tymes; et sic
de ceteris.