LESSON XLI 



THE SENSE ORGANS (Continued) 

 VISION 



1. The Near and Far Points of the Eye. Hold a pin 50 cm. from 

 your eyes and move it slowly toward them until a point has been reached 

 beyond which this object no longer produces a clear image. Measure 

 the distance of this point from your eyes and determine whether, in 

 accordance with your age, it is situated at a normal distance. Deter- 



FIG. 113. OPHTHALMOMETER. (Hardy) 



mine the near point for each eye. In the emmetropic eye the far point 

 lies at the horizon. 



Select a number of students with abnormal vision and determine 

 the near and far points in each. Ascertain whether they are far-sighted 

 or near-sighted. 



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