A correspondent writing to US- from Washington, D. C, gives it as his opinion that if books and papers were printed with white ink on black or dark colored paper, reading would not be so injurious to the eyes as it is at present. He says :—" The great flare which is reflected from the white pages distresses the delicate organ of vision, and interferes with the prompt transmission of the reflected letters to the retina." Our attention was directed to the same subject, about two years ago, by a California correspondent, and published in a former volume. We are not inclined to adopt the opinion of our correspondent, especially as it regards paper with a black ground and white ink. If in reading, the eyes have to recognize a hundred letters per minute, the rays of light must be both absorbed and reflected a hundred times in that period. The eye is, therefore, subject to severe labor in reading, not on account of the white reflected light from the paper, but frequent intermittent absorption and reflection of light. This accounts for the effect called "dazzling," which is produced by looking for a very brief period on a piece of white and black checked cloth, the stripes of which are very fine, and of equal breadth— the black stripes absorb, and the white reflect the rays of light. SOMETHING USEFUL.—Francis & Loutrel, No. 45 Maiden Lane, are extensive manufacturers of stationery of all kinds. They have a very large assortment of memorandum books for the year; also every style of account-book; writing paper ; copying, seal and card presses; manifold letter writers, fancy and staple stationery.