Axioms on quadrable and non-quadrable surfaces
Rules for what remains squarable when squares or curved parts are added to or removed from a figure
A largely text page setting out axioms on the quadrature of surfaces: what remains squarable (quadrabile) or non-squarable (inquadrabile) when squares or curved parts are added to or removed from a figure. A key 'conception' holds that if a curved surface loses its curvature, or an equivalent of it, the surface remains squarable or squared, and that a surface regains its former quantity when its removed parts are restored. The left column gives chapter headings on the quadrature of wholly curvilinear surfaces and of curvilinear surfaces mixed with straight sides. The ink is faint and the writing is in mirror script.
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Rules of quadrable and non-quadrable remainders
Leonardo lists paired rules: if from a square you take a quadrable figure the remainder is quadrable; if from a non-quadrable figure you take a square the remainder is non-quadrable; if from a non-quadrable surface you remove a non-quadrable part the remainder becomes quadrable. A 'conception' adds that a curved surface stripped of its curvature (or its equivalent) remains squarable, and that a surface regains its former quantity when its removed parts are restored.
Chapter headings on curvilinear quadrature
The left column carries two chapter titles: 'On curvilinear surfaces entirely, and their quadrature,' and 'On curvilinear surfaces mixed with straight sides, and their quadratures.' A further fragment ('Lio…') breaks off.