A Partitioned Rectangle and Circular Rings
A 10-by-12 rectangle split 20/70/30 (total 120); annuli with parallel chords a b c d
This leaf mixes numbered partitions with ring figures. A rectangle ten by twelve is divided into three strips of 20, 70 and 30, totalling 120, beside a vertical line met by arcs at points 2, 7 and 3. Two circular rings (annuli) labelled a, b, c, d carry parallel chords d n b and c m a said to meet their bounds at spherical right angles. The page continues the notebook's geometry of the circle and of proportional division.
On this page
A rectangle 10 by 12 split into 20, 70 and 30 (total 120)
A rectangle whose sides are marked 10 and 12 is divided into three strips carrying 20, 70 and 30, and the sum 120 is written beneath. The figure sets out a proportional, numbered partition of the rectangle's area.
A vertical line met by arcs at points 2, 7, 3
A vertical line is connected with a horizontal one, the horizontal marked at 2, 7 and 3 and the vertical at 10 and 12. Arcs swung across the figure relate the two lines.
Circular rings with parallel chords (a b c d)
Two circular rings (annuli) are drawn with the corners a, b, c and d. Leonardo notes that the lines d n b and c m a are parallel and form spherical right angles at their ends a b c d.