those having less than 10 points, it was found that 53 persons being 
long-sighted had as an average 19,2 points but those 102 beeing short- 
sighted only 18,0 points. 839 persons without eyeglasses had 19,3 points 
as an average. The standard deviation was roughly the same for all 
three groups, 
A new instrument for testing purposes 
A simple instrument has been designed and built and will be used 
in further studies. When designing it the author has tried to eliminate 
some of the "bugs" in the two methods described above. There is a 
parallax-measuring device included in it and a possibility to vary the 
strength and colour of the illumination. The first test-picture 1s shown 
in Fig. 3. A general view 1s given in Fig. 4. 
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