The works of Edmund Gunter: : containing the description and use of the sector, cross-staff, bow, quadrant, and other instruments. With a canon of artificial sines and tangents to a radius of 10.00000 parts, and the logarithms from an unite to 10000: The uses whereof are illustrated in the practice of arithmetick, geometry, astronomy, navigation, dialling, and fortification. And some questions in navigation added by Mr. Henry Bond, teacher of mathematicks in Ratcliff, near London. To which is added, the description and use of another sector and quadrant, both of them invented by Mr. Sam. Foster, late professor of astronomy in Gresham Colledge, London, furnished with more lines, and differing from those of Mr. Gunters both in form and manner of working (1673)
Gunter, Edmund, 1581-1626 · London : Printed by A. C.[larke]. for Francis Eglesfield, at the Marigold in St. Paul's Church-yard · leaf 43
• The Defertptmtf Lines, i$ ABC, ADE, fiiall be equianglcd « by reafcm of the common Angle at A, and the equal Angles at the Bafe, and therefore fhall have the Sides p$ppomonai about thofc equal Angles, by Prop,$.Lih6. of Eh f lid. … The Side A D fhall be to the Side A B, as the Bafis, D E, unto the parallel Bafis B C, and by converfion A B fhall be unto AD, as B C unto D E ; and by permutation AD fhall be unto DE, as AB to B C, &c. So that if A D be the fourth part of che Side A B, then D E fhall alfo be the fourth part of his…
