The earth as a star; sunlight bent through the air
With a note on sea waves and the deep valleys that form between them
The page begins with a hydraulic observation: the higher the sea's waves rise above the ordinary water level, the deeper are the valleys between them, the great fall of a wave hollowing out its trough. It then sets out a program for "proving the earth to be a star": first define the eye, then show that the twinkling and rays of stars arise in the eye rather than the star, and argue that a real twinkling equal to the body of a star larger than the earth would demand impossibly fast motion. Finally it treats how solar rays, passing through the thicker air at the boundary of the sphere of fire, make celestial bodies look large at rising and setting and small at mid-sky, illustrated by two diagrams of the elemental spheres lettered a, n d m, h f g and others.
On this page
Wave height and the depth of valleys between waves
The higher the sea's waves rise above the ordinary height of its surface, the lower are the bottoms of the valleys interposed between those waves; the great fall of the great waves makes a great concavity of valley.
A program for proving the earth is a star
The order of proving the earth to be a star: were the twinkling of a star as great as it appears, showing a dilation equal to the star's own body, then for a star larger than the earth such motion made in an instant would be too fast to double the star's size.
Twinkling and rays of stars arise in the eye
First define the eye, then show how the twinkling of a star comes from the eye, and why it is greater in one star than in another, and how the rays of the stars are born from the eye.
Solar rays refracted through the thicker air at the horizon
Let the earth be a; let n d m be the surface of the air bordering the sphere of fire; let h f g be the course of the moon or of the sun. When the sun appears at the horizon g, its rays pass through the air between unequal angles, o m, which is not the case at d K, and they pass through a greater thickness of air, all e m being thicker air; hence celestial bodies look large at rising and setting and small at mid-sky.