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

And as verreyly shaltow finde up-on thyn est orisonte thyn assendent.

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And for more declaracioun, lo here thy figure.

[6.] To knowe the spring of the dawing and the ende of the evening, the which ben called the two crepusculis:

[Ad cognoscendum ortum solis et eius occasum, que vocatur vulgariter crepusculum.]

Set the nadir of thy sonne up-on 18 degrees of heighte among

thyn almikanteras on the west syde, and ley thy label on the degree

of thy sonne, and thanne shal the poynt of thy label schewe the

spring of day. Also set the nadir of thy sonne up-on 18 degrees

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