Page:Popular Science Monthly Volume 47.djvu/484

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habit of making lid-pressure on the cornea, the resulting astigmatism being of no advantage, but always a disadvantage.

2. If he wishes to render himself relatively near-sighted, or, as he would state it, throw the eye out of focus, it is better to wear at his work a pair of convex glasses. The inconvenience of removing and replacing these could be obviated by spectacles made after the plan of the ordinary bifocal glasses, or, still better, by having the upper half cut away entirely, leaving for the lower a convex glass of such a strength as that individual would find most convenient for his special variety of work. In this way he is at least rid of the annoyance of constantly walking back and forward to obtain the effect of distance.

3. It is an undoubted advantage to every artist to ascertain the degree in which his eyes vary from the normal standard. Such a formula could be easily obtained. If the degree of error is but slight, of course it can be disregarded; if decided, and not properly corrected, knowledge of that variation from the normal in the artist's vision, if given in some way to the observer, would, without doubt, often win more favorable criticism for his work.

The logical and imaginative reader will perhaps picture to himself the art catalogue of the future, with a formula for the amount of imperfect vision (ametropia, as the oculists call it) added to each title. Thus:

No. 42. A Summer Morning. Myopic astigmatism, 1·5 dioptre, vertical meridian.

No. 44. He Cometh Not. Cylindrical, minus 0·5 dioptre, with spherical, minus 1·5, axis forty-five degrees.

This may seem rather like the "schedule of emotions," as it was once called, which was printed on the weekly programme in the earlier days of the Boston Symphony Orchestra, but none the less some such cataloguing of pictures would probably assist the critics and give the artist the satisfaction of more praise.

4. As the.corollary of the last proposition it should be said that the observer, in order to see a picture to the best advantage, must adjust his vision to that of the artist who produced it. Most of us do this instinctively. Not only do we select the best point of view from which to observe a picture, but we recede from the painting until the lights and colors blend in just the right degree. In addition to that, many instinctively pinch the eyes together, producing thus a momentary astigmatism, such as the artist had produced in his own eye, and find the picture thus apparently improved. A most useful appliance for viewing pictures is the so-called stenopaic slit. This is merely a slit one or two millimetres in width in a card or thin plate of brass. Simple as this device is, but few persons are aware of how much it adds to the effect in viewing paintings, as it allows the rays of light in only