ON THE INFLUENCE OF SCHOOL-BOOKS UPON EYESIGHT. 303 
for it involves difficulty in passing from the end of a line to the 
beginning of the line below.. Very wide space, on the other hand, 
has no advantage as regards legibility, and involves waste of paper 
and undesirable increase in the size of the book. Columns 4 and 5 
of the table indicate a suitable proportion. 
9. The length of the line also is a matter of importance. Other 
things being equal, the longer the line the greater the excursions of 
the eyes and the greater the difficulty in passing from one line to the 
next. Very short lines, on the other hand, demand too frequent a 
change of direction in the movement of the eyes. The use of lines 
longer than the maxima given in the last column of the table is sure to 
cause fatigue to a considerable proportion of readers. 
Approximate uniformity in length is desirable; but not absolute 
uniformity. It is doubtful whether the power of fairly rapid intelligent 
reading can be attained without the unconscious performance of the 
swing from near the end of each line to near the beginning of the 
next. This swing may be compared with the motion of an oarsman’s 
body between the strokes. A slight indentation in the lines helps the 
reader ; but a large one hinders the acquisition of a good habit of swing. 
Children of eight years old should not have their reading confined to 
very short paragraphs, as the habit of swing has been found well 
established in good readers of between nine and eleven years of age. In 
other words, these readers made the necessary eye-mmovements without 
conscious effort and with great regularity. 
Unusual separation of letters should be avoided. For 
beginners, lines should not end in the middle of a word; the whole 
word should be carried to the next line and not be hyphened. The 
admission in the table of a four-inch line for the large type is a 
concession intended to meet the difliculty of securing an even set of the 
letters in a line of shorter measure. 
Good margins are restful to the eye, and are well worth their 
slight cost. 
10. Particular Requirements of Special Subjects: Bibles, Prayer- 
books, and Hymn-books.—lt is to be regretted that these books are so 
frequently printed in type which is injurious on account of its small 
size. It is desirable that the standard given in the table should not 
be lowered with respect to these important books, which are frequently 
used under poor conditions as regards illuminaticn. 
11. Books for Evening Work.—The unfavourable conditions result- 
ing from artificial illumination and fatigue of the learners make it 
highly desirable that the rules ‘ from age twelve ’ should be maintained 
for books to be used in all evening classes, or for home-work, even 
for adults. ; 
12. Uzercises, Sets of Examples, and Questions.—These are the 
most important parts of a school-book, so far as influence upon vision 
is concerned, and the rules for the printing of them should on no 
account be less stringent than those applied to the rest of the book. 
The same rules should be applied to test-cards. The use of hektograph- 
ing or other multiplying processes is increasing in schools. Care should 
be taken to secure clear and legible copies. 
