Proportions of an Ionic Capital
Measured divisions of volute, ovolo, abacus, and astragal
A red-chalk drawing of an Ionic capital with scrolled volutes and an egg-and-dart ovolo, set at the foot of the sheet and keyed with the letters o, m, a, n, r, t, s and b. Above it Leonardo lays out the proportional divisions of the capital: the whole height a b is divided into nine and a half parts, with the abacus, ovolo, astragal and fillet each assigned a fraction. Several members are also measured as fractions of the segment r o.
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Ionic capital keyed with letters
The capital shows a pair of volutes flanking a central egg-and-dart ovolo above a beaded astragal, keyed with the letters s, o, r and others along its base. The projection of the ovolo is set at 1/6 of r o. The drawing sits directly below the column of measurements.
Fractional division of the capital's members
The height a b is divided into 9 1/2 parts: the abacus takes 3/9, the ovolo 4/9, and the astragal and fillet 2/9 and 1/2. Further ratios give a b as 1/3 of n m, m o and the ovolo's projection each as 1/6 of r o, and s t as 1/5 of r o.