HANDBOOK OF THE CLASSICAL TRADITION
The Ionic Column
The Ionic column shown in the plate illustrates the Attic Base which is commonly used in the Ionic order. This base has an extra torus or â€œatticâ€ above the lower torus. Both tori are separated by two fillets and a scotia.
As with the Doric order, the base is D high and has an 8/6 D wide plinth. The plinth is 1/6 D high or 1/3 the height of the base. A large torus sits above the plinth and has a fillet at its centerline. To draw the scotia, it is best to first construct the smaller torus with its flanking fillets and then place a swooping curve between the offset fillets of the two tori. Note that the upper fillet above the smaller torus is part of the shaft and not the base.
The shaft is divided into 24 semicircular hollows or flutes which are separated by fillets. Each flute is four times wider than the fillet. When drawn freehand, the flute is about 1/9 D.
The Ionic Capital is shown in front elevation which shows the scroll volutes in elevation. From the top of the abacus to the bottom of the volutes is slightly more than D.
Drawing of the capital is facilitated by the use of a dashed line on each side of the column centerline which follows the line of lower D. From that line, the square abacus projects 1/18 D. The volutes below the abacus follow the geometry of the abacus and help visually mediate between the round echinus and astragal below. On the left side of the capital, a section through the capital at the centerline shows the horizontal channel of the volutes which is straight in relation to the rounded elements.
The eye of the volute is centered down 1/3 D from the top of the abacus and across D from the center line of the column; its diameter is 1/18 D. Drawing the volutes with precision can be accomplished by following the diagram on the succeeding plate. If the volutes are drawn by hand at a small scale, they can be drawn by creating a series of half circles which get progressively smaller as they move closer to the eye. There is a space of 2/3 D between each volute.
Horizontal dimensions for the echinus and astragal can be carried over from the section to construct these elements in elevation. The echinus almost always has the egg and dart or egg and talon ornamentation. There are generally three eggs visible. Sprigs of honeysuckle fill in the gap between the end eggs and the volute.
The Ionic Entablature
The Ionic entablature can be divided into 18 parts to derive the heights of its main components. The cornice is 7 parts (7/8 D), the frieze is 6 parts (6/8 D), and the architrave is 5 parts (5/8 D). The total height of the entablature is 2 D.
The cornice projects out from the entablature 7/8 D, which is the same dimension as its width. Like the mutulary Doric Order, the cymatium consists of a large cyma recta followed by a smaller cyma reversa. The corona sits below the cymatium and should be undercut with a drip to soften the appearance of its underside and protect the building façade from water.
A large bed mold with an ovolo, dentils, and a cyma reversa sits below the corona. To determine the location of the ovolo in relation to the corona, one can first draw the dentils starting with the one centered above the column. Each dentil is 1/6 D high by 1/9 D wide. The space between dentils, or interdentil, is 1/18 D so that the width of the dentil plus the interdentil equals 1/6 D. The rightmost of the dentils is a double dentil without a space which indicates the dentil as it turns the corner. Above the projection of the fillet of the double dentil is the start of the ovolo.
The frieze is often straight but sometimes pulvinated, or bowed. A 60 degree equilateral triangle defines the pulvination and is shown as a dashed line.
The architrave has an upper and lower fascia. At the top of the upper fascia is a fillet and cyma reversa which projects from the architrave the same dimension as its width. The upper fascia is wider that the lower one. A small ovolo and fillet separates the two fascias.
The Ionic Volute Construction
The volute may be constructed at a large scale using the following steps:
1. Divide the height of the volute into 8 equal parts. From the top of the volute come down to the fifth division and draw
a circle whose diameter is equal to the height of the division. The circle represents the eye of the volute which has a diameter of 1/18 D.
2. Inscribe a square within the circle rotated 45 degrees. Divide the square into four equal quadrants as shown in the eye diagram. Divide each line which defines the quadrants into three equal divisions.
3. Label each point on the line with a number. Start with 1 at the upper right line and move counter clockwise around the square to number 4. Next move inside the square to points 5, 6, 7 and 8. Finally, label the inner divisions 9, 10, 11 and 12. Each point is where one places the compass point to construct the volute.
4. Starting with point one for the compass point move the drawing lead directly vertical to the top of the volute and swing the compass 90 degrees counter clockwise until one reaches point 2. The compass point is then placed on point 2. From point 2, one moves the compass 90 down to point 3. From point 3, the compass moves up to the right to point 4. This exercise is repeated until on reaches point 12. As one moves to point 12, the radii will become increasingly smaller. The final rotation from point 12 will bring the final arc into the eye.
5. To draw the fillet of the volute, mark a quarter division within each of the existing divisions on the eye diagram. The quarter point should be set toward the face of the circle. Starting with the quarter division between points 5 and 1, swing the compass to the quarter division between 2 and 6. Continue moving the arcs counter clockwise with the quarter division at point 12 and the center of the circle being the last compass point.