Damp, foggy weather, the reflection of the bright sunshine, intense cold, dusty wind, reading on cars in motion, reading by gas or lamplight when the light falls directly on the eyes, sitting before a glowing fire, wearing of glasses when not needed, wearing veils, and all indulgences that weaken the nervous system, injure the eyes. The most pleasing light for work is from a northern exposure. A shade that protects the eyes from the light that falls on paper, book or work is an advantage. The light should not come from different points, but that from behind the worker is best, A very weak or very bright light should be equally avoided. Diseases of the eye are often the result of general weakness, and in such cases local treatment has little effect. In fitting glasses to the eye great care should be taken to adjust the lens to the eye with accuracy. Crown glass is preferable to flint, on account of its superior hardness, its entire want of color, and its non-decomposition of light. Scotch pebbles are unobjectionable except as to cost.