i8 / Geometrical JnflruBions \ 

 Wepafsnow to the Conftruaion cf Potygoiiar 



: ^;v. , PROPOSITION X.^ 



s- ^'I'To^frayne a Fentagon upon a given Line. 

 • ;«uppofe the Line B A v trom the End A,andfrom 

 the Interval A B defcribe the Arch B D F. Then 

 elevate the Perpendicular A C •, divide the Arch B G 

 into five Parts eqaally, I D L M K. Then draw the 

 right Line A D, cut the Bafe A B into two equally 

 in O •, elevate the Perpendicular O E from the Sedi- 

 on E, and from the Interval E A defcribe the Circle 

 A B F G H ^ bring five times the Line A B within 

 the Circumference of the Circle, and' you fliall have 

 a Pentagon regular, equi- angle, equj-lateral, AB 

 F"G H. Fig. 1 and 2. ^0 ^xi. ^i^-^ ^ 



The PraBice upon tie Groiinl -Fig. ?. 

 Is the fame, and is particularly ufeful la Centers 

 and Cabinets of a Gardener Wildcruefsi -, forwhea 

 a Walk runs thro' or into one of them, you mult 

 firft fet oft' on each Side that Walk h^lf the Width, 

 as you may fee on the Ground -, and this wxU . be 

 the giveh Line, as in the Queftion ^ from which 

 you- may with Eafe and Certainty make a propor- 

 tionable Center or Cabinet. Vide Fjg. 3.' ' 

 P R O P O S I T I O N XL 

 :iA'.:-. Within a Circle to make a Pentagon, 

 -T^he Circle being given, there will not be Vo 

 frlitth Trouble as there was in the other. Draw 

 then the two Diameters A B, CD, dividing them, 

 felves at Right Angles in £., divide the halt Dia- 

 materia: E into two equally in F, and from the In. 

 terval F A, defcribe the Arch A G from the Point 

 A- andfrom thelnten^ai A G ddfcribe^the Arch 

 G H. The Line A H Ihall divide the Circle into 

 five equal Parts. TWeFig. ^. 

 -.7: TloePraBiao'yithe Grmm f. /• 



. .Isthe fame, the Line performing the Part of the 

 Compafs. Vide^ Fig. 6. 



