_e. Atmosphere and Perspective._ We are all familiar with the diminished size of objects seen at a distance and realize that the apparent coming together of two parallel lines, as those of a railway track, is owing to the same cause. We know, too, that this diminishing must be shown in a picture or there is no sense of distance for the spectator. What is not so clear to us usually, is that there is as great a difference in color and the appearance of objects. The diminution of size is linear perspective and the change of color due to distance and atmospheric conditions is commonly called aerial perspective. The tendency among amateurs is to paint a tree green no matter how far away from the spectator it is, while a little observation and study would show the veriest tyro that the green of a distant tree has faded till to the eye it looks a bluish gray. Moreover, outlines have faded and seem to flow into those of other objects, and all combine to give to the picture the true appearance of distance, which is what the artist seeks and the one who looks at the picture has a right to expect. _f. An Application of the Foregoing Principles._ What has been said on this subject of judging a picture may be made clearer by an application to one of the pictures in _Journeys_. Let us take, for instance, the color plate facing page 304, in Volume VI. It is a reproduction in color of the painting in water colors, _Bob and Tiny Tim_, and will show what is meant by the comments above almost as well as the original painting would have done. 1. Tone and color. Are the colors in the picture bright and gay or are they subdued? What are the brightest colors? Are the colors harmonious or do they "quarrel" as they come to the eye? Are the shades of blue and purple and lighter colors in the clothing of the various persons glaring or subdued? Do you observe any inharmony which offends the eye, or are you pleased with contrasting colors and tones? The harmony in color is due to the choice of colors that do not contrast too strongly. The artist knew which were complementary colors; that is, which, united, form white. Which colors in the picture do you think show warmth, and which show cold, as suitable to out-of-door scenes? What effect on the rest of the picture does the olive green of the interior of the room have? What effect does the gray green of the open door have? 2. Light and Shade. Is the picture flat and without appearance of life, or do the persons and objects stand out in a life-like manner? Are parts of the picture in shade, so that outlines are lost? The artist has shown the left of the building in the foreground as in shadow; how is this effect produced? Do you observe gradations of tone in the shawl on Tiny Tim, which indicate relative light and shadow? Where is the highest light in the picture, and where the darkest shadow? Are the lights strong as if the sun were shining, or soft and diffused, as is noticeable on a snowy winter's day?