Pyramidal heaps of pebbles and the level of water
A heap's slope follows the square's diagonal; the water surface seeks equal distance from the centre.
In red chalk the sheet studies heaped pebbles. An upper box shows a hatched triangular pyramid of gravel, with the rule that the sides of any discrete quantity heaped into a pyramid follow the obliquity of the diagonal of a perfect square. Below, two heaps of round pebbles are stacked, one steep and one sloped. A second note turns to water, arguing that every part of the water's surface seeks equal distance from the centre of the elements, so that any part standing higher does so through contrary motions riding over one another between it and the bottom.
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Slope of a pyramidal heap of pebbles
A triangular pile of gravel is drawn in a box. The note states that the sides of any discrete quantity heaped into a pyramidal congregation follow the obliquity of the angular diameter, the diagonal, of the perfect square, i.e. a fixed angle of repose.
The water surface seeks a level
The second note argues that every part of the water's surface desires to lie equally distant from the centre of the elements. Where one part of the surface rises above another, it happens through contrary motions that ride over one another between the surface and the bottom.