There is an old tradition that the eyes are strengthened, and the vision preserved in old age, by rubbing the closed eye-lids frequently with the finger in a horizontal direction. About three years ago there was considerable excitement in this city, by persons professing to cure weakness of vision, yea, even restoring faded sight, by manipulating the eye-balls. The New York " Scalpel" treats such pretensions as delusive, and asserts that such treatment as mechanical manipulation, tor the eyes, is positively injurious. It cites some cases where great injury resulted to those who submitted to rubbing of the eyes for the cure of taded sight, and instances a case of a man who lost his sight forever by some one—a friend— who thoughtlessly came behind him and closed his eyes firmly with his hands, calling upon him to guess who it was—a not uncommon custom among thoughtless young people. The eye is so very tender—is such a fine piece of mechanism, that it must be handled and treated with great care and gentleness. Many become short sighted at an early age, constitutionally or by sickness, or by imposing too much labor upon those wonderful organs. In health the eyes will undergo much fatigue, but they are as capable of being over-taxed as the arms, or the limbs. Much reading or writing, by artificial light, is very trying to . the eyes, especially if the light is unsteady, too brilliant, or too weak. A good full light) shaded with a light blue globe, is the best to read or write with during evening hours. Upon no consideration should a man read more than four hours at once, by artificial light, and he should give his eyes ten minutes' rest after he has read two hours; this is the experience we have gathered from not a few persons. Those who are blessed with strong eyes should not over-tax them, as many zealous students do, by too much night study, or a3 some merchants do, by too much night writing. There are instances on record of a sudden loss of sight by strong men, who had read and written by lamp-light, as if their eyes never would fail, an4- their vision never loae its pow* er. The celebrated Euler lost his eye-sight by an imprudent night's study, in some of his mathematical calculations. The smoke of lamps is very hurtful to the eyes, hence a good circulation of air is as necessary for the eyes as for the lungs. The " Scalpel" asserts that it is injurious to wash the eyes by dipping the face in a basin and opening the eyes in the water, and recommends cold tea or milk and water, for bathing the eyes in preference to water itself. A very weak solution of the sulphate of zinc is excellent for blood-shot or surface-inflamed eyes; we have never known it to fail in effecting a cure in a few days.