The Fifty-third Figure B.
Three different Ways of delineating wreath’d Columns.
The wreath’d Columns describ’d in the Fifty-second Figure, being divided into Twenty-four equal Parts, want very much of that Elegancy of Contour, which is visible in those brass Pillars, made by the famous Cavalier Bernino, for S. Peter’s Sepulcher in the Vatican. Wherefore I here lay before you three several Ways of diminishing the Spaces through the whole Height of the Column.
1. Make the right Line OA equal to AB the Height of the Column; then draw the Line OB, and on the Center O describe at pleasure the Arch AP, which divide into twelve equal Parts, and by the Divisions draw streight Lines from the Center O to the Line of the Column; and lastly continue the same Parallels to the Base. The Spaces between these Parallels, shall be the Sides of equilateral Triangles, wherewith you are to describe the Wreath of the Column, as is seen in Column 1.
2. Having set the third Part of the Columns Height, from the Bottom of the Shaft to the Point C; with the Interval CD, from the Centers D and C, describe the Parts of Arches intersecting at E. On the Center E, with the same Interval, describe the Arch DC, which divide into twelve equal Parts; and from the Points of those Divisions, draw Parallels to the Base. Then dividing each Space between the Parallels into four equal Parts; three of those Parts shall be the Sides of the Isosceles Triangle; whose Vertex is the Center whereon to describe each Wreath of Column 2.
3. Having drawn from the midst of the Columns top G, the Line GF, make HI equal to HF, and draw IL parallel to the Base HF: Again, make IN equal to IL, and draw NM also parallel, and so on. In small Pillars, the Centers of the Diagonals of these Spaces may, without sensible Errour, serve for describing the Wreaths; but in greater Columns, either of the other two Methods is rather to be chosen.
Fig. liv.