Quadrature of lunes: circles, squares, and hexagons
Portions and proportions of curved figures, with a note for a Turkish summer drink
Two mounted sheets crowded with Leonardo's geometrical game of curved figures: squares filled with interlaced curvilinear motifs, circles tiled with hexagons and stars, and rows of lunes and two-angled 'portions'. The text works out which curved pieces are 'squarable' and how the portions of one circle equate to those of another, reasoning by the principle that from a known quantity a known part removed leaves a known remainder. Numerical proportions run through it, such as dividing eighty-four portions by six to get fourteen, or judging one circle octuple or quadruple to another. Tucked among the diagrams is a recipe note for a summer drink of sugar, rosewater, lemon and cold water strained through white cloth, called the drink of the Turks.
On this page
From a known, a known removed leaves a known
A square with curvilinear sectors labelled b a, c d carries the governing rule: if from a known you take a known, the remainder is known. Since both the hatched region and the whole square are known, subtracting the hatched leaves a squarable remainder, and the un-hatched part is worth half the square a b d c. The same maxim recurs along the median fold.
Octuple proportion between two circles of portions
A circle carrying 24 two-angles is set against a greater circle: forty-eight portions in the smaller answer to six in the greatest. The proportion is therefore octuple, so the greatest circle is octuple to the smallest, and dividing forty-eight by eight returns six. Like part answers to like part as like whole to like whole.
Hatched portions squaring the greatest circle
Above a sun-like circle Leonardo notes that eight of the hatched pieces are worth the four greatest portions of the greatest circle, so the remainder is squarable. Elsewhere twelve two-angles within a quadruple circle are judged worth the greatest square of the greatest circle. The figures test when curved slivers can be exchanged for straight-sided equivalents.
Squares of interlaced curvilinear motifs
The upper left of the sheet is filled with a grid of small squares bearing symmetric interlaced and knotted curvilinear designs. Though drawn as geometric quadrature exercises they read as decorative panels of applied ornament. Further faint pen labelling accompanies several of them.
A cooling drink of the Turks
Set to the right of the geometry is an unrelated household jotting. Sugar, rosewater, lemon and fresh water are strained through white cloth, and this, Leonardo writes, is the drink of the Turks in summer. It is a memorandum of a recipe rather than a study.
