254 THE WONDERFUL HOUSE THAT JACK HAS 



black to the eyes than others, it is regarded as evidence 

 of astigmatism. 



This defect is a hindrance to clear and easy vision, 

 as letters are made up of lines running in different 

 directions. Its cure is in the use of glasses that correct 

 the defect in the form of the eye. Neither the concave 

 glasses helpful in nearsightedness, nor the convex lenses 

 that relieve farsightedness, will be of any use. In 

 fact, if neither of the above glasses gives the desired 

 ease and clearness of vision, it is almost a sure sign 

 that one's trouble is astigmatism. The relief and 

 comfort following the use of the properly fitting 

 glasses is so great that one feels his oculist is, indeed, 

 a benefactor. 



There are important parts of the eye that have not 

 been mentioned in this chapter. Many interesting 

 things concerning these useful organs have also been 

 purposely omitted, for the aim has been to give only 

 names and facts necessary to such an understanding of 

 our eyes as will enable us to keep .them in the best 

 condition for service. There are also many disorders 

 of the eyes to which no reference has been made. The 

 three defects that have been described are the most 

 common ones that the use of glasses will permanently 

 correct, and many others that have not been men- 

 tioned result from a lack of correction of these. 



For example, squint or cross-eye is often caused by 

 farsightedness or some other defect too severely over- 

 taxing certain sets of muscles. Squint usually starts at 



