Art. 1. Objects of Geometrical and Physical Optics 2 — 5. Definitions of a self luminous body, a medium, a ray, a pencil, the axis of a pencil 7 — 10. Laws of Re?ection and Refraction. Nature of their proof 11. Finite velocity of light 12, 13. Illumination of surfaces 15 — 17. Definitions of Geometrical focus, principal focus, focal length.