438 SCIENCE OF HOME AND COMMUNITY 



pair of spectacles brings about a most remarkable change 

 in enabling him to see things he has never seen before, so 

 that all life takes on a new aspect. Glasses should be fitted 

 only by a competent oculist. 



School work requires so much use of the eyes that care 

 should be taken to reduce as much as possible the strain on 

 the eyes. There should be the proper amount and kind of 

 light in the schoolroom. The books used should be printed 

 on good paper and the type should be plain and large, 

 especially for growing children, larger than that required 

 for adults. An excessive amount of 

 written and home work should be 

 avoided. 



Testing the eyes. Nearsightedness 

 may be easily detected by means of 

 the Snellen card. This is a card 

 with a series of letters of different 

 sizes showing the distance at which 

 each size of the letter can be seen by 

 FIG. 174. - Lines to test the aver age eye. Each eye is tested 



astigmatism. J J 



separately, and if a person is near- 

 sighted, it is shown by the inability to read the letters at 

 the standard distance. Farsightedness may be tested by the 

 same card, and is shown if a child can see a line of letters at 

 a greater distance than that marked on the card. To test 

 for astigmatism, a card is used containing a number of lines 

 extending in different directions from a common center like 

 spokes of a wheel. Astigmatism is shown if certain lines 

 appear blacker than others. 



DEMONSTRATION 34 



Purpose. To test the eyes of the members of the class. 



Apparatus. Snellen's vision chart. 



The eyes of the members of the class may be tested by using 



