The Path-Way to Knowledg, Containing the First Principles of GeometrieRecord, Robert
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The Path-Way to Knowledg, Containing the First Principles of Geometrie
Record, Robert
Geometry -- Early works to 1800
Howe bee it, it happeneth so sommetymes, that the pricke on
whiche you would make the perpendicular or plum line, is so nere
the eand of your line, that you can not extende any notable
length from it to thone end of the line, and if so be it then
that you maie not drawe your line lenger frõ that end, then doth
this conclusion require a newe ayde, for the last deuise will
not serue. In suche case therfore shall you dooe thus: If your
line be of any notable length, deuide it into fiue partes. And
if it be not so long that it maie yelde fiue notable partes,
then make an other line at will, and parte it into fiue equall
portiõs: so that thre of those partes maie be found in your
line. Then open your compas as wide as thre of these fiue
measures be, and sette the one foote of the compas in the
pricke, where you would haue the plumme line to lighte (whiche I
call the first pricke,) and with the other foote drawe an arche
line righte ouer the pricke, as you can ayme it: then open youre
compas as wide as all fiue measures be, and set the one foote in
the fourth pricke, and with the other foote draw an other arch
line crosse the first, and where thei two do crosse, thense draw
a line to the poinct where you woulde haue the perpendicular
line to light, and you haue doone.
_Example._
[Illustration]
The line is A.B. and A. is the prick, on whiche the
perpendicular line must light. Therfore I deuide A.B. into fiue
partes equall, then do I open the compas to the widenesse of
three partes (that is A.D.) and let one foote staie in A. and
with the other I make an arche line in C. Afterwarde I open the
compas as wide as A.B. (that is as wide as all fiue partes) and
set one foote in the .iiij. pricke, which is E, drawyng an arch
line with the other foote in C. also. Then do I draw thence a
line vnto A, and so haue I doone. But and if the line be to
shorte to be parted into fiue partes, I shall deuide it into
iij. partes only, as you see the liue F.G, and then make D. an
other line (as is K.L.) whiche I deuide into .v. suche
diuisions, as F.G. containeth .iij, then open I the compass as
wide as .iiij. partes (whiche is K.M.) and so set I one foote of
the compas in F, and with the other I drawe an arch lyne toward
H, then open I the cõpas as wide as K.L. (that is all .v.
partes) and set one foote in G, (that is the iij. pricke) and
with the other I draw an arch line toward H. also: and where
those .ij. arch lines do crosse (whiche is by H.) thence draw I
a line vnto F, and that maketh a very plumbe line to F.G, as my
desire was. The maner of workyng of this conclusion, is like to
the second conlusion, but the reason of it doth depẽd of the
.xlvi. proposiciõ of y^e first boke of Euclide. An other waie
yet. set one foote of the compas in the prick, on whiche you
would haue the plumbe line to light, and stretche forth thother
foote toward the longest end of the line, as wide as you can for
the length of the line, and so draw a quarter of a compas or
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