4. In addition to acquiring the thr

4. In addition to acquiring the three habits described above, a shooter may find it desirable to strengthenhis tolerance for light. This may be done as described in the following paragraphs:a. Sunlight is very beneficial to the eyes. It both relaxes and stimulates. But it is necessary to knowhow to use the sunshine to get the most out of it. Sunlight directly on the eyes may cause greatdamage. The eye can be strengthened in its light tolerance by judicious exposure to light. One ofthe most effective and simple ways of strengthening the eyes is to expose them to the sun's raysin the following manner:(1) Close the eyes lightly as the face is turned directly toward the sun. Keeping the eyes closed,slowly turn the head from side to side. Keep this up for four or five minutes. Then, when theeyes are relaxed from the heat of the sun and the motion of the head, they may be opened,but only momentarily, and when the head is turned to the side. The eyes must not lookdirectly at the sun but may look near it. Make no effort to see, and open the eyes only inflashes. As this exercise is continued, and the eyes become accustomed to the increasedlight, the glance may be directed closer and closer to the sun.(2) By doing this with regularity on successive days and for a gradually increasing length of time,any eye will be strengthened and its vision improved.b. The eye is admirably equipped to protect itself and function under widely varying light conditions.When the natural protective mechanism is used, as just outlined, strong light will be handledeasily by the eye.