Chapter 6

On the Figures of transparent bodies which serve for Refraction and for Reflexion.

General and easy rule to find these Figures.

Invention of the Ovals of Mr. Des Cartes for Dioptrics.

How he was able to find these Lines.

Way of finding the surface of a glass for perfect refraction, when the other surface is given.

Remark on what happens to rays refracted at a spherical surface.

Remark on the curved line which is formed by reflexion in a spherical concave mirror.