“Now please look at the ‘Bay of Rainbows’ in the photograph before us. Cape Laplace at its western end lies close to the terminator and appears as a minute speck of light. The great bow-shaped shore is clearly defined, the level surface within being very dark and the highlands around it comparatively bright. The crater mountain Bianchini you will recognize near the center of the bow. Several other similar crateriform mountains are visible toward the north and east. In this light the surface of the moon eastward from the North Pole appears as rough and broken with craters and crater plains as we saw in the earlier pictures that it is toward the west. “Before directing our attention to photograph No. 20, let us return for a moment to Aristarchus. When speaking of that formation a few minutes ago I interrupted myself in order to give you the scale of tints on the moon, which demonstrated the unique brilliance of the peak inclosed by the ring. I intended to point out to you then the fact that in photograph No. 19 we see, for the first time, not only the ring of Aristarchus but its curious neighbor Herodotus. A light streak, which we observed in an earlier picture, seems to connect the two. It is better, however, to notice this now because in turning from No. 19 to No. 20 you will perceive once more a change in the appearance of Aristarchus and its neighborhood. In No. 20 Aristarchus is distinctly more conspicuous. The night has advanced during almost exactly twenty-four hours, having in the meantime swept across the entire length of the ‘Bay of Rainbows,’ which we now no longer see. If we had been using a telescope during that interval we should have beheld a very interesting spectacle, for sunset on the ‘Bay of Rainbows’ is quite as remarkable, although in a very different way, as sunset on the Bay of Naples. The astronomer, seated amid the lonely gloom of his observatory dome, and watching the change of light and illumination on the surface of the moon, has many an hour of solitary enjoyment of aspects of nature that are quite impossible on the earth, and that frequently lure him into poetic meditations which find no place in his notebook.” “I am very glad to hear you say that. It enhances my opinion of the astronomers, and convinces me that after all they are not so severely scientific as they describe themselves.” [Illustration: NO. 20. AUGUST 17, 1903; MOON’S AGE 24.84 DAYS. ]