In Plate II. I give a diagram of its rectilinear orthography, which is simply constructed by lines drawn, either horizontally, vertically, or obliquely, which latter make with either of the former lines one or other of the harmonic angles in the above series. For example, the horizontal line AB represents the length of the base or surface of the upper step of the substructure of the building. The line AE, which makes an angle of (¹⁄₅) with the horizontal, determines the height of the colonnade. The line AD, which makes an angle of (¹⁄₄) with the horizontal, determines the height of the portico, exclusive of the pediment. The line AC, which makes an angle of (¹⁄₃) with the horizontal, determines the height of the portico, including the pediment. The line GD, which makes an angle of (¹⁄₇) with the horizontal, determines the form of the pediment. The lines EZ and LY, which respectively make angles of (¹⁄₁₆) and (¹⁄₁₈) with the horizontal, determine the breadth of the architrave, frieze, and cornice. The line _v n u_, which makes an angle of (¹⁄₃) with the vertical, determines the breadth of the triglyphs. The line _t d_, which makes an angle of (¹⁄₂), determines the breadth of the metops. The lines _c b r f_, and _a i_, which make each an angle of (¹⁄₆) with the vertical, determine the width of the five centre intercolumniations. The line _z k_, which makes an angle of (¹⁄₈) with the vertical, determines the width of the two remaining intercolumniations. The lines _c s_, _q x_, and _y h_, each of which makes an angle of (¹⁄₁₀) with the vertical, determine the diameters of the three columns on each side of the centre. The line _w l_, which makes an angle of (¹⁄₉) with the vertical, determines the diameter of the two remaining or corner columns. In all this, the length and breadth of the parts are determined by horizontal and vertical lines, which are necessarily at right angles with each other, and the position of which are determined by one or other of the lines making the harmonic angles above enumerated.