Studies of the classical orders: architrave, arch and pedestal
Rules for corbels, vault springing and column-to-pedestal proportion, over a faint compass construction
The upper part of the sheet gathers studies of the classical orders: an architrave carried on columns (marked a), an arch on two columns, and the proportion of a column to its pedestal. Leonardo notes practical rules — placing a corbel so the floors above the beams stay level, fixing where a vault springs relative to the ovolo and architrave, and setting the column shaft at three-quarters (6/8) of its pedestal's width. The lower half of the leaf is filled with a large, faint compass-and-straightedge construction of circles and inscribed triangles. Further untranscribed notes accompany a small boxed perspective sketch at upper right.
On this page
Corbel set at a to keep the floors level
Where a bracket or corbel is introduced — marked a — Leonardo places it so that the floors carried on the beams do not come out unequal, and so that a thick beam need not be set where none is required. The note belongs to the architrave-on-columns study at upper left.
Where the vault springs above the ovolo
For the arch carried on two columns, the upper surface of the vault is said to finish above the ovolo moulding and to begin above the architrave. The remark fixes the vertical relationship of arch, echinus and entablature.
Column base is three-quarters of its pedestal
The shaft of the column at its foot is given as 6/8 the width of its pedestal — that is, three-quarters. The rule is noted beside the small pedestal study.
Large compass construction filling the lower sheet
Below the architectural sketches the leaf is covered with a faint compass-and-straightedge construction: a large circle crossed by radiating lines and inscribed triangles. No transcription is provided for it, and it is described here only from what is drawn.