760 



POPULAR SCIENCE MONTHLY. 



eleven (position on cliart at 9, a year and a half above the aver- 

 age of their age), shows the vertical recorded nearly upright 

 fifty-one times, greatest variation twenty degrees, while the ob- 



COMPOSITE or 53 

 AVERAGE AGE IIYLARS 



POSITIOM e ON CHART 

 POINTS AIMED AT 



lique lines of the trapezium show the maximum possible varia- 

 tion forty-five degrees, with few lines near the right slant. 



The so-called child drawing, so much written about of late, 

 that Herbert Spencer and many others deem of educational im- 

 portance, may be described as line making without conscious 

 effort the graphic record of a muscular movement associated 

 with a concept. It becomes more plausible as years advance, 

 but never gets beyond caricature, and has no direct educational 

 value. 



Drawing, to have educational value, must be the graphic 

 record of a perceived fact. 



divided by 2. To get per cent, divide bv 2 again and subtract from 100, because yg^ 

 inch = 1 per cent. Thus, total error, 2'1 inches; greatest angle error, 7'2. 

 2-1 -- 7 = -3 ; T-2-:- 24 = 3 ; 



3 



;3 100 



^H-2 = 3h-2 = -15; ^ 



85 per cent. 

 When time is limited and an approximation is desired, the greatest angle error treated 

 as above will give a result within two per cent of an average for a class. 



The angle error may ))e ignored where the personal position is not desired, as it will 

 change the average center but little, the personal position very much, particularly of the 

 concept recorders. 



