_Protection of the Eyes from the Glare of the Sun._—In very hot weather the eyes should always be so protected that the rays of the sun do not shine directly into them. This protection may be afforded by the brim of the hat or by a parasol. At the sea-shore, or on an ocean voyage, where the glare of the sun is constant and particularly trying, the eyes should be protected by wearing slightly tinted smoked glasses. =Artificial Lighting.=—The main sources of artificial lighting are kerosene, gas, and electricity. The principal questions of importance are the quantity and quality of the light, its steadiness, the vitiation of the atmosphere by the products of combustion, and the expense; also the proper arrangement of the light. Kerosene is the most extensively used means for artificial lighting. The principal objections are—the heat, the trouble of filling and keeping the lamps in order, and the danger of explosion and fire if upset; the odor and the great vitiation of the atmosphere. The modern lamp gives a brilliant light, and if properly shaded by a slightly bluish chimney, so as to absorb the excess of yellow rays, it is very satisfactory. Illuminating gas, as furnished in cities, has a great excess of yellow rays, which are very injurious to the eyes, and the vitiation of the atmosphere is very considerable. Gas-light is modified by the Argand and Bunsen burners. Of these, the Bunsen burner, a patented composition burner, heated to incandescence, is the best. It gives a white light, resembling daylight, and, under proper adjustment, a far greater volume than any other burner. It is not so hot, does not consume as much gas, and so there is less vitiation of the atmosphere. It is intensely brilliant, and must be shaded by ground glass or a proper shade. Electricity gives the very best light, with a minimum amount of heat and vitiation of the atmosphere. For individual use 16-candle power is sufficient. The lamp-shade should be opaque, of a dark-green color, and lined with a white, reflecting surface. Transparent lamp-shades, especially when patterned, are always bad, whatever their color; because of the different degree of illumination thrown upon the work, the light is irritating to the eyes. =Hygienic Precautions in Reading and Sewing.=—There should be free access of open daylight. Near the window is obviously the best place for working, and the seat should be so selected that the window is to the left of the worker. This prevents the work from being shaded by the hand, and protects the eyes from being fatigued by the light falling directly into them. Any room will have too much light into which the sun shines directly. Even if the worker’s face is not turned directly toward the sun, yet the light reflected from the book or other work will be so intense as to be dazzling. The softest and most pleasant light to work by is the diffused light from the northern sky. An excess of light may be easily regulated by a shade.