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

Furthermore, yif thou wilt knowe in umbra versa, by the craft of

umbra recta, I suppose thou take the altitude at the poynt of 4, and

makest a marke; and thou goost neer til thou hast it at the poynt of

3, and than makest thou ther a-nother mark. Than muste thou

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devyde 144 by eche of the poyntes be-fornseyd, as thus: yif thou

devyde 144 be 4, and the nombre that cometh ther-of schal be 36, and

yif thou devyde 144 be 3, and the nombre that cometh ther-of schal be

48, thanne loke what is the difference be-tween 36 and 48, and ther

shalt thou fynde 12; and right as 12 hath him to 12, right so the space