EYES AND SCHOOL-BOOKS. 57 



average of the results of tlie examinations in twenty-five German and 

 Swiss gymnasia with 9,096 scholars, the percentage of short-sighted 

 pupils rose from the sexta to the prima as follows : 22, 27, 33, 46, 

 52, 53. 



These numbers speak plainly enough. Still there are persons who 

 doubt that children become short-sighted at school. In order to make 

 this more clear, I examined the pupils of the Friedrichs Gymnasium 

 at Breslau in 1871, and repeated the examinations upon the same per- 

 sons three semesters afterward. Seventeen pupils who had been 

 found normal-sighted at the first examination had become short- 

 sighted, and more than half of those who had appeared near-sighted 

 at first had become more so. Similar results have been obtained 

 by Dr. A. von Reuss in the Leopold Stadt Gymnasium at Vienna, 

 by Dr. Seggle in the Cadet Corps at Munich, and by Dr. Derby at 

 Boston. 



It is evident that we are threatened with a great national affliction, 

 w^hich is likely not only to be detrimental to all peaceful occupations, 

 but to impair the military efficiency of our people. It is important to 

 seek out the causes of this ever-growing evil and contest them with 

 energy. We can not discuss here all the causes that tend to produce 

 myopy. All protracted looking at close objects may contribute to it. 

 Among the more active causes may be mentioned badly-constructed 

 school-benches, imperfect lighting, too much reading, bad writing, and 

 bad type. The matter of the style of typography which is most com- 

 patible with the preservation of the eyesight deserves especial con- 

 sideration. The most important point is the size of the letters. We 

 can not determine this by the measurement of the em, as the printers 

 do, for that regards the shank of the type, of which readers know noth- 

 ing ; but it must be judged by a special measurement of the visible 

 letter. I have adopted as the standard of measurement the letter n, 

 that being the most regular and symmetrical in shape in both the 

 Roman and German alphabets. I have found that the n in pearl 

 type is about 0*75 millimetre (or about y|^ of an inch) high, in 

 nonpareil 1 millimetre (or about -^^ of an inch), in brevier (petitschrift) 

 1^ millimetre (or about -f-^ of an inch), in long primer (corpusschrift) 

 IJ millimetre (Jy inch), and in pica (Ciceroschrift) If millimetre 

 (tV inch). 



We have hitherto had no definite rules concerning the smallest size 

 of letters which should be permitted for the sake of the eyes. The 

 distance at which a letter of any particular size can be seen does not 

 afford a guide to it, for it does not correspond at all with the distance 

 at which matter printed in the same type can be read steadily, at the 

 usual distance in reading. I believe that letters which are less than a 

 millimetre and a half (Jy inch) high, will finally prove injurious to the 

 eye. How little attention has hitherto been paid to this important 

 subject is exemplified in the fact that even oculistic journals and books 



