ON THE INFLUENCE OF SCHOOL-BOOKS UPON EYESIGHT. 287 
is increased. The reading of Ordnance Survey 
sheets by the older pupils is not objected to, 
provided they are used in good daylight. 
16. Music——For the tonic sol-fa notation the 
minimum height of the short letters should be 
(a) for music, 2mm.; (0) for words, 1-5 mm. Staff 
music is often produced by lithography, in which 
all gradations of size and shape are possible. Care 
in printing is needed, so as to secure well-defined 
stave-lines and tails. Advantage should be taken 
of the elasticity in the length assigned to different 
bars in the lithographed music, so as to avoid 
compression of complicated passages. For begin- 
ners music of the size of the ‘Giant Note’ is 
recommended. For others, the stave-lines should 
not be less than 1°75 mm. apart, or the four spaces 
should measure not less than 7 mm. The ruled 
paper for music-writing should have lines not less 
than 2 mm. apart. 
17. Greek. Greek type is troublesome to 
beginners by reason of its unfamiliarity and of the 
difficulty of synthetising accents and letters into 
word-wholes. Type which has a line of uniform 
thickness affords easy discrimination of individual 
letters, and is legible in mathematical formule, 
even when small sizes are used. The variety - 
Greek type which employs fine hair-lines should 
be entirely abandoned. For reading, it is recom- 
mended that no type smaller than twelve-point be 
used for beginners, or eleven-point for experienced 
readers. 
18. German.—The older styles of German type 
are not easily legible, partly on account of the ill- 
placed hair- lines : at the top of the letters: Recent 
forms of the black letter used in German books 
are improved in this respect; but since Roman 
