938. In viewing objects very near the eye, the ciliary processes are called into action to produce a proper inclination of the crystalline lens, so that the rays of light may be properly refracted to form a perfect image on the retina. In looking at objects at a great distance, the ciliary processes are called into a different action, to produce a different inclination of the lens. Let either of these actions be repeated, again and again, for weeks and months, and they will become natural, and the acquired inclination will be permanent. 939. From the preceding principle, a person becomes short or long sighted, as the objects to which the eye is usually directed are near or remote. This is one reason why scholars, watchmakers, and artisans, who bring minute objects near the eye to examine them, are short-sighted, and why hunters and sailors, who are habituated to view objects at a distance, are long-sighted. _Observation._ In the management of children, whether in the nursery or school-room, it is very important that their books, or articles upon which they may labor, should be held at an appropriate distance from the eye. Were this attended to by the parent or instructor, we should not see so many persons with defective vision. 940. Cleanliness, as well as the health of the eye, require that it be bathed every morning with pure water, either cold or tepid, accompanied with as little rubbing or friction as possible. In all instances, the secretion from the lachrymal glands, that sometimes collects at the angle of the eye, should be removed, as it contains saline matter. 941. When small particles, or dust, get upon the eye, they produce much inconvenience, which is often increased by harsh attempts to remove them. The individual should be placed before a strong light, the lids held open with one hand, or by another person, and the particles removed with the corner of a fine linen or silk handkerchief. -=-=-=-=-=-=-=-=-=-=-=-= 938. What is the effect of repeatedly using the eye in one direction? 939. Why are artisans and scholars generally short-sighted? Why are sailors and hunters long-sighted? How can defective vision in a great degree be prevented? 940. What reasons are there for bathing the eye? 941. How can dust and other small particles be removed from the eye? -=-=-=-=-=-=-=-=-=-=-=-=