146 APPLIED PHYSIOLOGY 



away from the eyeball so as to catch whatever might fall 

 against the eye. 



287. Dirt under the lids. The front side of the eyeball 

 and the lining of the lids are very tender. If only a little 

 dirt gets under the eyelid, it gives great pain. Then the 

 eye should be kept still until the dirt can be taken out. 

 Rubbing grinds the dirt into the eye and makes it sore. 

 Never rub the eye when you think it has something in it. 

 Lift the lid by the eyelashes and the tears will usually 

 wash the dirt away. If they do not, let some one raise 

 the lid and pick out the dirt with a soft handkerchief. 



288. Tears. The eyeball is moistened with a saltish 

 liquid called tears. They are produced by a gland situated 

 just above and to the outside of the eye. They run over 

 the. surface and down a small tube, and into the nose. 

 Winking rubs the liquid over the whole surface of the eye 

 so as to wash away dust. When you cry, the tears flow 

 faster than the tube can carry them into the nose. Then 

 some overflow upon the cheeks. 



289. Care of the eyes. Your eyes ought never to ache 

 from use. If they do ache, you are straining them and 

 may do them great harm. You can use your eyes safely 

 until they begin to ache. At the first signs of discomfort, 

 you should stop work and give them a rest. 



A bright light in front of the eyes is the most common 

 cause of eye strain. At night there should always be a 

 shade over the lamp, or else you should wear a shade over 

 your eyes. A cap will do for a shade if you cannot get 

 anything else. 



The light should come from one side or over your 

 shoulder. Then it will not shine into your eyes. You 

 should never try to look at the sun. You should never try 

 to read by a dim or unsteady light. 



