Sand heaps, a divided circle and a number series
Rule that a sand pile is twice as wide at the base as at its axis
Two triangular heaps of sand are drawn at the top, one on the flat and one on a slope, with a red-chalk rule that every such heap is twice as wide at its base as at its axis. A circle crossed by two extended diameters sits at the right. Below are the heading 'arithmetic' and the number series 2 3 5 8 12, with a small indeterminate sketch at the foot of the page.
On this page
Proportion of a heap of sand
Leonardo states that every heap of sand, whether resting on the flat or on a slope, spreads twice as far at the base as at its axis. Two small triangular piles illustrate the rule.
Circle with two extended diameters
A circle at the right is crossed by two diameters drawn out beyond its circumference. It is noted in red chalk alongside the sand-heap study.
Number series 2 3 5 8 12
Under the heading 'arithmetic' Leonardo writes the series 2 3 5 8 12, whose successive differences increase by one at each step. It sits with the other proportional notes on the sheet.