Proportional division of a triangle by parallel cuts
A geometrical rule on cuts parallel to the base, opened by a maxim that experience without reason misleads.
The transcribed notes treat the geometry of a triangle: as a section is taken from the base toward the opposite apex the figure shrinks by the same degrees that it would grow going the other way, and a cut drawn parallel to the base is as much smaller than the base as the base is greater than it. The passage opens with Leonardo's maxim that whoever expects from experience what is not in it departs from reason. Around the geometric figures the crowded sheet also carries mechanical and structural sketches and a large central drawing, and much of its mirror-script text remains untranscribed.
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A triangle shrinks toward the apex as it grows toward the base
Following the opening maxim on experience and reason, the note states that a triangle diminishes at every degree of its length from the base to the opposite angle by just as much as it grows from the angle back to that base by the same degrees. The rule is stated symmetrically for measuring in either direction.
A cut parallel to the base compared with the base
A cut made in a rectilinear triangle parallel to the base is as much smaller than that base as it would be greater if it were raised to the position of the base. Equivalently, the parallel cut is as much smaller than the base as the base is greater than it.
Untranscribed mechanical and structural sketches
Beyond the geometry, the sheet is filled with small mechanical and architectural sketches at the left margin and along the lower half, together with a large branching central drawing. These are drawn rather than transcribed and are not covered by the given text.