Page:Popular Science Monthly Volume 1.djvu/188

 178 haze which is produced by the diffusion of light in Turner's pictures after 1831 should have a particular attraction for many of Turner's admirers. On the other hand, passing over the faults, we discover in these pictures peculiar merits, and we recognize that the great artist continued in many ways to improve, even at a time of his life when his failing sight began to deprive his works of general favor. I cannot, however, defend the opinion of those who are enraptured with Turner's pictures belonging to a still later period—who consider a picture beautiful which, in consequence of this optical defect, is entirely disfigured and defaced, and who, calling this Turner's style, would like to form it into a school and imitate it. They resemble the porter of a certain dealer in works of art, who one day, when he had to deliver the torso of a Venus at a gentleman's house, answered the servant, who had expressed his astonishment that his master should have bought a thing without head, arms, or legs, "You don't understand; that's just the beauty of it."

I show you here first a picture which is copied from an oil-painting in the South-Kensington Museum. This picture was not exhibited till the year 1833, but it was painted some time before, and from sketches taken in Venice previous to any change in Turner's sight. I shall now try so to change this picture, by an optical contrivance, as to make it resemble the pictures he painted after 1839. You must, of course, not expect to see in this rough representation, which a large theatre necessitates, any thing of the real beauty of Turner's pictures. Our object is to analyze their faults.

In order to show you in a single object what you have already observed in the general aspect of a picture, I choose purposely a tree, because there are no trees in the "Venice" you have just seen, and more particularly because after the year 1833 Turner painted trees that were unknown to any botanist, had never been seen in Nature, nor been painted by any other artist. I do not think it likely that Turner invented a tree he had never seen; it seems to me more probable that he painted such trees because he saw them so in Nature. I searched for them with the aid of the lens, and soon discovered them. Here is a common tree; the glass changes it into a Turner tree.

Let us now turn from the individual case of a great artist to a whole category of cases, in which the works of painters are modified by anomalies in their vision—I mean cases of irregularities in the refraction of the eye. The optical apparatus of the eye forms, like the apparatus of a photographer, inverted images. In order to be seen distinctly, these images must fall exactly upon the retina. The capacity of the eye to accommodate itself to different consecutive distances, so as to receive on the retina distinct images of objects, is called accommodation. This faculty depends upon the power of the crystalline lens to change its form. The accommodation is at its