Dividing lines and circles with a single compass opening
Equal and unequal partitions, with columns of arithmetic
The verso is filled with concentric circles, arcs and light construction lines exploring how to partition figures with a fixed compass. Leonardo states problems for dividing a whole circle or any part of it into equal portions using the same compass opening that drew it, and for dividing a line into equal or into unequal parts with a single random opening. Arcs at the lower right are labelled as eighth, quarter and half, and a small column of arithmetic sits alongside.
On this page
Equal partition with the drawing compass unchanged
Divide the whole circle, or any part of it, into as many equal parts as wished using the same compass opening that made it; and divide a line into equal parts with a single random opening of the compass. The arcs at lower right are marked 1/8 (eighth), 1/4 (quarter) and 1/2 (half).
Unequal partition with one compass opening
In a passage written with the sheet turned upside down, Leonardo claims that with a single opening of the compass he can also divide a line into unequal parts, the counterpart to the equal-division problems above.
Numerical working beside the constructions
A small cluster of figures (100; 15 15; 3; 100 7; 15) accompanies the geometric problems, reading as calculation attached to the partitioning of lengths.