The inversion of the image, with a converging light-ray diagram
Rays crossing at a point turn right into left, with a braced stand at the right
The upper half of the sheet is filled with a bold diagram of rays fanning out from and converging upon a point, passing a small disc. A note on the lettered figure below explains that when rays cross, the upper parts on the right become left in the lower and the left become right, the principle of image inversion through a point or aperture. To the right stand braced framework sketches resembling a stand or rig, and further mirror-script text beneath the ray figure is present but not included in the transcription.
On this page
Inversion of the image: right becomes left
On the paired figures c b a and a b c, the upper a corresponds to the lower a, and the same holds for b and c. All the upper parts on the right become left below, and the left become right, the crossing of rays that inverts an image.
Rays converging through a point
The large upper diagram shows straight rays fanning out and crossing at a point, passing a small round body. It illustrates in the large the inversion described in the note below.
A braced stand or rig
At the right, drawn more lightly, is a braced framework with legs and cross-members resembling a stand, easel or trestle. It is sketched separately from the optical diagram and carries no transcribed label.