Boiling Upwellings in Rivers; Section of the Elements
How water rebounds from the riverbed, and how one element penetrates another
Two studies fill the page. The first explains that mound-like 'boilings' rising in a current mark great depth: water strikes the bottom, rebounds upward through the overlying flow, then loses momentum and sinks back around its center toward the bed. The second opens a 'section of the five natural elements' (fire, falling air, fire, air, water, earth) treating how one element penetrates another and comparing this to the falling air of fire turning a mill. Marginal diagrams of crossing lines and a column of descending bubbles beside a numbered scale accompany the notes.
On this page
Boiling upwellings as a sign of great depth
Where mounds rise in running water in the manner of boilings, this signals great depth. The upwelling springs from water striking the bottom and rebounding, piercing the overlying water and turning toward the surface. Gaining weight it loses its first course and falls back around its center toward the bed.
Section of the five natural elements and their powers
A section labels fire, falling air, fire, air, water and earth, proposing to describe the figures one element makes in penetrating another and their relative powers. The falling air of fire will turn the mill, as fire issuing from air, air falling from water, and earth falling from water. The qualities of the powers, resistances, and figures made in passing through are to be described.
Marginal diagrams of crossing lines and descending bubbles
The right margin carries small ink diagrams: two X-shaped crossings of lines bearing short letter labels, and a vertical column of circles descending beside a numbered scale. They illustrate the section of the elements and the paths of penetration described in the text.