Quadrature studies and the plan of the Stable of the Magnifico
Squaring circles and lunes, with a horse-stable plan for 128 horses
A crowded verso continuing Leonardo's quadrature campaign, filled with circles inscribed in squares, biangles, lunes and star-figures that he reduces to the greatest square of the greatest circle by adding and removing 'maxima' portions. He cites Euclid's proposition that circle is to circle as square is to square, and references Hero on waters. Set among the geometry are two ground plans of the 'Stable of the Magnifico', 110 braccia long and 40 wide, divided into four rows of horses and 32 intercolumns each holding two horses, giving a capacity of 128 horses. The writing is small mirror-script and partly abraded.
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Ground plan of the Stable of the Magnifico
Two planimetries describe the Stable of the Magnifico as 110 braccia long and 40 braccia wide. It is divided into 4 rows of horses, each row split into 32 spaces called intercolumns, every intercolumn holding two horses separated by a bar, so the stable can hold one hundred and twenty-eight horses.
Euclid: circle is to circle as square is to square
Two squares double one to the other stand with their centres on the centre of one circle, which touches the angles of the lesser square and the sides of the greater. The circles are double in proportion, one touching the angles and the other the sides of the same square, and from this Euclid said the proportion from circle to circle is as that from square to square built on the diameters.
The four maxima and the greatest square
Across many figures Leonardo repeats that where the four maxima are missing the remainder is worth the greatest square of the greatest circle. Biangles are shown worth the four maxima, and a labelled circle abcdfegn is declared worth the greatest square of the greatest circle.
Equal figures: remove equals, leave equals
Because the first and second figures are one same value, Leonardo removes equal parts from each: taking the four portions bcde from the first and hg from the second leaves the curvilinear aLm of the first equal to the square rectilinear nmpq of the second. A parallel figure fills the voids fg with ab so the reintegrated second figure stays square and equal to the first.
