This is a vintage scientific illustration titled "FRANGES POLYCHROMATIQUES" (Polychromatic Fringes) from a series called "LES PHÉNOMÈNES DE LA PHYSIQUE" (The Phenomena of Physics), specifically "PLANCHE VI" (Plate VI). The illustration is a grid of four panels, each depicting a different pattern of polychromatic fringes, likely resulting from light interference or diffraction. **Panel 1 (Top Left):** Shows a circular pattern of colorful fringes radiating from a central point. The fringes are arranged in concentric rings, with colors transitioning from red, orange, yellow, green, blue, indigo, and violet. **Panel 2 (Top Right):** Displays a linear pattern of colorful fringes, resembling a series of stacked rectangles or pixels. The colors are arranged in a sequence similar to the first panel, creating a rainbow-like effect. **Panel 3 (Bottom Left):** Presents a more complex circular pattern with numerous concentric rings of colorful fringes. The fringes are densely packed and appear as small, elongated ovals. **Panel 4 (Bottom Right):** Shows a linear pattern of colorful fringes, with the fringes appearing as parallel lines. The lines are arranged in a sequence of colors, creating a rainbow-like effect. Below the grid, there are signatures and labels in French, indicating the artist and the title of the illustration. The background is black, which emphasizes the vibrant colors of the fringes. The overall style is reminiscent of early scientific illustrations, with a focus on precise detail and accurate representation of physical phenomena.