Geometrical constructions and a note on double proportion of motion
Compass constructions of a rectangle, wheel and lever sketches, and a lattice of interlocking circles
The left half (f. 70v) carries a compass construction of a rectangle from two free points a and b, alongside small sketches of wheels on axles, a levered arm, a compass-drawn arc and a little polyhedron. A short note states a rule of double proportion in which motion, movers and triangles are all doubled. The right half (f. 71r) is dominated by a large geometrical figure combining a triangle, a semicircular arc and a dense lattice of interlocking circles forming a quatrefoil pattern, with small divided circles beside it. Further untranscribed lines of text are present down the left margin.
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Constructing the rectangle o from two free points
Two points a and b are placed at will and joined by the straight line a b. The line a b is then cut orthogonally by a line running from the centre n and extending to m; the orthogonal cut yields the rectangle o.
Double proportion of motion and movers
A brief rule accompanying a figure: in double proportion the motion is doubled, the movers are doubled, and the triangles are doubled. It ties a proportional scaling of the geometric figures to a doubling of motive force.
Lattice of interlocking circles within a triangle and arc
A large construction sets a triangle and a semicircular arc over a grid of interlocking circles that form a repeating quatrefoil pattern, with small circles at the side divided into shaded segments. It reads as a study of the proportional division and packing of circular figures.