When you haue any peece of the circumference of a circle
assigned, howe you may make oute the whole circle agreynge
therevnto.
First seeke out of the centre of that arche, according to the
doctrine of the seuententh conclusion, and then setting one
foote of your compas in the centre, and extending the other foot
vnto the edge of the arche or peece of the circumference, it is
easy to drawe the whole circle.
_Example._
A peece of an olde pillar was found, like in forme to thys
figure A.D.B. Now to knowe howe muche the compasse of the hole
piller was, seing by this parte it appereth that it was round,
thus shal you do. Make in a table the like draught of y^t
circumference by the self patron, vsing it as it wer a croked
ruler. Then make .iij. prickes in that arche line, as I haue
made, C. D. and E. And then finde out the common centre to them
all, as the .xvij. conclusion teacheth. And that centre is here
F, nowe settyng one foote of your compas in F, and the other
in C. D, other in E, and so makyng a compasse, you haue youre
whole intent.
[Illustration]