The strength of columns and the proportions of capitals
Opening with a prose passage on the ancient builders of cities
The sheet opens with a prose passage on the ancient architects, beginning with the Egyptians whom Diodorus Siculus describes as the first builders of very great cities, castles, and public and private edifices whose scale filled beholders with wonder. It then treats four types of column, noting where each is apt to break and that a column of uniform thickness and strength serves best. Detailed proportional rules follow for constructing a capital, its ovolo and abacus, before the text returns to proving the strength or weakness of columns geometrically. Small marginal sketches show columns, a capital, and a base.
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The ancient architects and the first builders of cities
A prose preamble names the ancient architects, beginning with the Egyptians, whom Diodorus Siculus records as the first builders of very great cities, of castles, and of public and private edifices. Their form, size and quality struck later beholders with stupefaction and wonder.
Where four kinds of column break
A column whose thickness is at the upper third is apt to break there; one whose bulk is below the middle breaks at both ends. A column of equal thickness and equal strength serves best, and second in worth is one thickest where it meets the base.
Proportions of the capital
The capital's thickness is divided into 7 at the top and given 5/7 at the foot, and made 5/7 high so that it comes out square. Its height is then divided into 8, with 1/8 for the ovolo and another eighth for the abacus tablet above.
Section of the capital and projection of its horns
The horns of the capital's tablet project 2/7 beyond the greatest width of the bell, each horn 1/7, and the chamfer of the horns should be as wide as high, 1/8. The rest of the ornament is left to the sculptors' discretion before the text turns back to proving column strength by lines drawn from summit to base.