CONTAMINATED AIR 165 



real difference to the abilities and development of the boys. 

 Records were obtained for two hundred and one boys. 



Of course it is not to be supposed that the grade-difference 

 between smokers and non-smokers is due entirely to the fact 

 of smoking. It is probable that the more scholarly boys do 

 not take to smoking, so that if those who smoked had never 

 done so, their marks would probably not be as high as the 

 highest marks, on the average. Nevertheless the advantages 

 seem to lean in favor of the non-smokers. 



(45) 

 (55) 

 (24) 

 (77) 



J i I i I i I . I i I i L 



5 10 15 20 25 30 35 40 45 50 55 GO 05 70 75 80 85 90 95 100$ 

 FIG. 56. Smoking and school standing 



The school grades of two hundred and one Illinois high-school boys. The numbers 

 in parentheses give the number of boys in the group. The forty-five who left school 

 during the year were habitual smokers. Twenty-four of the boys had learned to smoke 

 but had given up the practice. The average grade of the ten highest smokers was 

 78.9 per cent. The average of the ten highest in the school was 90.9 per cent ; none 



of these smoked 



The physical effects of tobacco on growing men has been 

 shown from the records of several colleges. 



At Yale the physical measurements of entering students 

 have been taken for many years back. Physical examinations 

 of students in college were made from time to time. At one 

 time the growth of the students, as indicated by a comparison 

 of the earlier and later measurements, was studied according 

 to the tobacco habits. The records were divided into three 

 groups, representing (i) students who never smoked, (2} those 

 who smoked irregularly, and (3) those who had been smoking 

 for a year or more before the second measurements were 



