The image shows a Lissajous figure, a mathematical pattern that visualizes the relationship between two perpendicular harmonic oscillations — typically represented as sinusoidal motions in the X and Y directions. Lissajous Figures are named after Jules Antoine Lissajous (1822–1880), a French physicist who studied these curves by reflecting light from tuning forks vibrating at right angles.

The reference to ""Les Récréations Scientifiques"" by Gaston Tissandier (a 19th-century popular science book) suggests that this image was part of a scientific or educational notebook demonstrating the phenomenon.

The figure itself appears to be a photographic or photogram recording of a light trace — likely produced using an oscillograph, pendulum, or a setup involving moving mirrors reflecting a light beam."