Quadrature series of lunes and circular portions
Figures each worth the last, decuple hexagons, and a leaf catalogued among clock-escapement studies
The verso continues the geometrical game, its upper half packed with rosettes, star-in-square figures and rows of lunes while the lower half is largely blank. Leonardo builds an ordered series, labelling figures 'first' through 'fifth' (and on to eight) in which each curved figure is declared equal in value to the one before, and reasons about which shapes are squarable and how portions of one circle equate to those of another. One tally divides sixty portions by six to get ten, leaving the greatest hexagon decuple to the smallest. In the Codex Atlanticus classification the sheet is tagged among Leonardo's clock-escapement ('scappamento') studies.
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An ordered series of lunes, each worth the previous
Leonardo lays out a numbered progression of curved figures along the median fold: the 'first' with parts a b c d equal, the 'second' worth the first, the 'third' worth the second, the 'fourth' worth the third and the 'fifth' worth the fourth, continued to six, seven and eight. Each step equates a reshaped lune or portion to its predecessor. The chain shows curved pieces conserved in value as they are rearranged.
Sixty portions and the decuple hexagon
A circular ring of two-angles inscribed in a square carries sixty portions. Dividing them by six gives ten, so the smaller circle enters the greater ten times, and ten of the smaller portions are worth one greatest portion. The greatest hexagon is thus decuple to the smallest hexagon.
A lune worth a figure, circles in quadruple proportion
In one double figure a is worth b with the circles double to one another, and d is the square of b. In another, a lune is worth b where the circles stand in quadruple proportion. A curvilinear triangle's upper portion is shown filling its two lower concavities to become a straight-sided triangle.
Rosettes and star figures in squares and circles
The upper sheet carries several finished decorative figures: an eight-petalled rosette in a square, a star tessellation within a circle, and small florettes in an octagon and circles. Drawn as quadrature exercises, they present as symmetric applied-art motifs. Much of the lower sheet is blank with only faint offset traces.
