Reader, your eyesight is worth more to you than any information you aro likely to gaiu from tliis book, however valuabl tbat niay be. You nre, thercfoic, earnestly cautioned: 1. To be sure that you have sufficient light, and that your position be such that you not only avoid the direct raye upou yonr oyes, but that you also avoid the angle of roflection. In writing, tho light should be received over the left shoulder. 2. That you avoid a stooping position nnd a forward inclination of tho head. Hold the book up. Sit erect also when you write. 3. That at brief intervals you rest the eyes by looking off and away from the book for a few moments. And you are f nrther cautioned to avoid as much as possible books and papers printed insinall type, and especinlly such as are poorly printed; also, to avoid straining or overtaxing the sight in auy ■way. Boys may need to be reminded of the great importance of thoroughly cleansmg the eyes with soft, pure water botli morning and evening.