Perpendiculars, a Subdivided Square, and 'On Local Motion'
Geometry diagrams above a heading De motu locali with a list of the Calculators
The upper part of the folio carries geometric diagrams: a line segment meeting an arc perpendicularly on its convex side, on its concave side, and meeting a straight line; an arc cut perpendicularly whose four resulting right angles are marked equal by dots; and a horizontally based square with both diagonals surmounted by an isosceles right triangle equal to half the square, filled with a diminishing series of diagonally divided squares. Below, under the Latin heading 'De motu locali' ('On local motion'), Leonardo lists authorities on the science of motion: Swineshead 'the Calculator', Heytesbury, Angelo da Fossombrone and Albert.
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Perpendicular meetings of line with arc and straight line
Three small figures show a line segment meeting an arc perpendicularly on its convex side, a line segment meeting an arc perpendicularly on its concave side, and a line segment meeting a straight line perpendicularly.
Square with diagonals and a diminishing series of squares
A square based horizontally is drawn with both diagonals. Above it sits an isosceles right triangle equal to half the square, within which a diminishing series of squares, each divided by diagonals, is nested.
De motu locali and the Calculators
Under the heading 'On local motion' Leonardo notes a set of authorities on the science of motion: Swineshead, that is, 'the Calculator'; Heytesbury; Angelo da Fossombrone; and Albert.