M. Javel, in a recent lecture, tries to answer the question, "Why is
reading a specially fatiguing exercise?" and also suggests some
remedies for this fatigue. First, M. Javel says reading requires an
absolutely permanent application of eyesight, resulting in a permanent
tension of the organ, which may be measured by the amount of fatigue
or by the production of permanent myopy. Secondly, books are printed
in black on a white ground; the eye is thus in presence of the most
absolute contrast which can be imagined. The third peculiarity lies in
the arrangement of the characters in horizontal lines, over which we
run our eyes. If we maintain during reading a perfect immobility of
the book and the head, the printed lines are applied successively to
the same parts of the retina, while the interspaces, more bright, also
affect certain regions of the retina, always the same. There must
result from this a fatigue analogous to that which we experience when
we make experiments in "accidental images," and physicists will admit
that there is nothing more disastrous for the sight than the prolonged
contemplation of these images. Lastly, and most important of all in M.
Javel's estimation, is the continual variation of the distance of the
eye from the point of fixation on the book. A simple calculation
demonstrates that the accommodation of the eye to the page undergoes a
distinct variation in proportion as the eye passes from the beginning
to the end of each line, and that this variation is all the greater in
proportion to the nearness of the book to the eye and the length of
the line. As to the rules which M. Javel inculcates in order that the
injurious effects of reading may be avoided, with reference to the
permanent application of the eyes, he counsels to avoid excess, to
take notes in reading, to stop in order to reflect or even to roll a
cigarette; but not to go on reading for hours on end without stopping.
As to the contrast between the white of the paper and the black of the
characters, various experiments have been made in the introduction of
colored papers. M. Javel advises the adoption of a slightly yellow
tint. But the nature of the yellow to be used is not a matter of
indifference; he would desire a yellow resulting from the absence of
the blue rays, analogous to that of paper made from a wood paste, and
which is often mistakenly corrected by the addition of an ultramarine
blue, which produces gray and not white. M. Javel has been led to this
conclusion both from practical observation and also theoretically from
the relation which must exist between the two eyes and the colors of
the spectrum. His third advice is to give preference to small volumes
which can be held in the hand, which obviates the necessity of the
book being kept fixed in one place, and the fatigue resulting from
accidental images. Lastly, M. Javel advises the avoidance of too long
lines, and therefore he prefers small volumes, and for the same reason
those journals which are printed in narrow columns. Of course every
one knows that it is exceedingly injurious to read with insufficient
light, or to use too small print, and other common rules. M. Javel
concludes by protesting against an invidious assertion which has
recently been made "in a neighboring country," according to which the
degree of civilization of a people is proportional to the number of
the short sighted shown to exist by statistics; the extreme economy of
light, the abuse of reading to the detriment of reflection and the
observation of real facts, the employment of Gothic characters and of
a too broad column for books and journals, are the conditions which,
M. Javel believes, lead to myopy, especially if successive generations
have been subjected to these injurious influences.
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