READING AND EYESIGHT.

Thames Star, Volume X, Issue 3174, 22 April 1879, Page 1

READING AND EYESIGHT.

M. Javel, in a recent lecture, tries to answer the question, Why is reading a specially fatiguing exeroise? 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 arrange* ment 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 successfully to the same parts of the retina, whilel 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 thai 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 the line. As to the rules Which M. Javel inculates in order that'the injurious effects of reading may be avoided, with; reference to the permanent application of the eyes, be 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 hare been made in the introduction of coloured 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 biVoeßh led to this coaclusidn both from" practical~c>bservation and also theoretically from the relation which must exist between the two eyes and the colours of the spectrum. His- third, advice is;to give preference to small volumes which can ,be held in the hand, which obviates the necessity-f f the book being kept fixed in one place, and . the? fatigue resulting from accidental inaages. Lastly, M.. the. avoidance of two long lines, and therefore he prefers small volumes,- and for the same reason^ those journals-which are printed iii Anarrow: fcoliinins/ Of'cdurse^ every one knows that it is exceedingly;injurious ia;read with;insufficient light; or to use too small print, and other-common; rules. M. Jayel concludes., hy s protesting r against an inridioua assertion which, has recently been made " in a neighboring country " (Germany, no doubt)* according to which the degree of civilisation of- a people is proportional!to the number of;the shortsighted shown to exist by sUtistie*; the extreme economy of; ligbt,-the abuse of reading to. theK'detrimbntfioff reflection and the observation- ,tif;"!real'facts, the employ ment, o^;<^bthic^cbaracj;erß and of a idKbr^ad^orumn fbt bßoWatfd journals arethe; <bonditions rwhic£,;MvJavol believes, lead: id njoptf'; especially if successive generation e^ r BubJeotcd ibjtheseinfluonceg^r^ffc Ul-, •-•.,,