Chaucer's Works, Volume 3 — The House of Fame; The Legend of Good Women; The Treatise on the Astrolabe; The Sources of the Canterbury Tales

by Geoffrey Chaucer

litil holes; and mete than the space fro thy foot to the baas of the

tour; and right as the nombre of thy poynt hath him-self to 12, right

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so the mesure be-tween thee and the tour hath him-self to the heighte

of the same tour. Ensample: I sette caas thy rewle falle upon 8;

than is 8 two-thrid partyes of 12; so the space is the two-thrid partyes

of the tour.

[42a.] Umbra Versa.

To knowe the heyghth by thy poyntes of umbra versa. Yif thy

rewle falle upon 3, whan thou seest the top of the tour, set a prikke