* * * * * OUTLINE IN PAINTING. A correspondent (J.O.W.H.) at p. 318. of Vol. i. asks a question on the subject of outline in painting; instancing the works of Albert Durer and Raffaelle as examples of defined, and those of Titian, Murillo, &c., of indefined outline. He wishes to know whether there is "a right and a wrong in the matter, apart from anything which men call taste?" The subject generally is a curious one, and has interested me for some time; as experiments exhibit several singular phenomena resulting from the interference and diffraction of rays of light in passing by the outline of a material body. As a matter of fact, I believe I may say, that there is no such thing in nature as a perfectly defined outline; since the diffraction of the rays, in passing it, causes them to be projected upon it more or less, according to the nature of the particular body, and the intensity of the light. And I may remark, by the way, that I believe this circumstance of the projection of a star upon the moon's disc at the time of an occultation, is to be accounted for on this principle (though with all due deference to higher authority); a phenomenon which is to this day unexplained. Of course every outline is rendered less defined by any motion of the eye of the observer, however slight. Hence, perhaps, the comparative indistinctness of outline commonly seen in pictures, compared with those in nature; as the artist {64} would be apt to take advantage of this circumstance, and give to his painting the same kind of effect the reality would have to an eye wandering over it; thereby taking away the attention from individual parts, and, as it were, forcing it to judge of the general effect, which general effect is, perhaps, the main object in painting.