To make a plumbe lyne on any porcion of a circle, and that
on the vtter or inner bughte.
Mark first the prick where y^e plumbe line shal lyght: and prick
out of ech side of it .ij. other poinctes equally distant from
that first pricke. Then set the one foote of the compas in one of
those side prickes, and the other foote in the other side
pricke, and first moue one of the feete and drawe an arche line
ouer the middell pricke, then set the compas steddie with the
one foote in the other side pricke, and with the other foote
drawe an other arche line, that shall cut that first arche, and
from the very poincte of their meetyng, drawe a right line vnto
the firste pricke, where you do minde that the plumbe line shall
lyghte. And so haue you performed thintent of this conclusion.
_Example._
[Illustration]
The arche of the circle on whiche I would erect a plumbe line,
is A.B.C. and B. is the pricke where I would haue the plumbe
line to light. Therfore I meate out two equall distaunces on
eche side of that pricke B. and they are A.C. Then open I the
compas as wide as A.C. and settyng one of the feete in A. with
the other I drawe an arche line which goeth by G. Like waies I
set one foote of the compas steddily in C. and with the other I
drawe an arche line, goyng by G. also. Now consideryng that G.
is the pricke of their meetyng, it shall be also the poinct fro
whiche I must drawe the plumbe line. Then draw I a right line
from G. to B. and so haue mine intent. Now as A.B.C. hath a
plumbe line erected on his vtter bought, so may I erect a plumbe
line on the inner bught of D.E.F, doynge with it as I did with
the other, that is to saye, fyrste settyng forthe the pricke
where the plumbe line shall light, which is E, and then markyng
one other on eche syde, as are D. and F. And then proceding as I
dyd in the example before.