Rays from a Light Source and from the Eye to a Circle
A construction of vision and illumination converging on a small circle
A clear ink diagram sets two marked points, one at upper right and one at left, from which bundles of straight rays are drawn down to a small circle in the lower middle of the sheet, the two pencils of lines crossing near it. The transcribed caption gives only a lettered figure, o a - p - m n. Further untranscribed notes accompany the drawing, marking one point as where the eye sees and the other as where light arises, so that the construction studies how the eye and a light source project onto the circular body.
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Convergence of visual and light rays on a circle
Two focal points, at upper right and at left, each send a fan of straight lines to a small circle low on the sheet, the pencils crossing near it. The drawing pairs the station of the eye with the source of light, studying how each projects rays onto the round body.
Lettered construction of the ray diagram
The figure is keyed with the letters o a - p - m n, marking points along the crossing rays and on the circle that fix the geometry of the construction.