608 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



prise to find that in the first normal measurement for this threshold on 

 Squad B, the average of the 10 men is 58.2", that is, 10" lower than the 

 average for the normal group of prospective aviators, the personnel of 

 which was supposedly selected with some reference to keen vision. 

 Naturally this factor of vision was a matter of pure chance in the selec- 

 tion of the personnel for Squad B. These first averages show almost 

 the same range as the normal series of 1917, that is, the range for B is 

 41" to 110". The latter figure (the record for Mac) is not included in 

 the average. If included, it would raise the average somewhat, but 

 not to the level of the average for the normal series of 1917. It is 

 regretted that no normal records are available for Squad A; their first 



^ Subject commonly wore glasses but not when tested. 



2 In the vertical axis Can has a threshold of about 48"; it is his pronounced astigmatism, there- 

 fore, that accounts for large M. V. of this subject. 

 ' The subject's father was a visitor in the room when these measurements were taken. 



measurement for this threshold was on October 13; this was the first 

 observation after food reduction, which began on October 4. The 

 average for the 10 men on this date is 86.2", and would not be 

 materially different if Spe and Fre were included. According to the 

 only available normals, this seems to be high. 



The individual values in tables 175 and 176 are, in each case, the 

 average of from 12 to 20 threshold determinations, distributed about 

 equally between the four axes which were used, as outlined on page 

 175. The mean variation computed by taking all of an individual's 



