The flanks or exterior banks of Theophilus, especially those on the west side, are studded with apparently minute craters, all of which when carefully scrutinized are found to be of the true volcanic type of structure; and minute as they are, by comparison, they would to a beholder close to them appear as very imposing objects; but so gigantic are the more notable craters in the neighbourhood, that we are apt to overlook what are in themselves really large objects. It is only by duly training the mind, as we have previously urged, so as ever to keep before us the vast scale on which the volcanic formations of the lunar surface are displayed, that we can do them the justice which their intrinsic grandeur demands. We trust that our illustrations may in some measure tend to educate the mind’s eye, so as to derive to the full the tranquil enjoyment which results from the study of the manifestation of one of the Creator’s most potent agencies in dealing with the materials of his worlds, namely, volcanic force. So rich in wonderful features and characteristic details is this magnificent group and its neighbourhood, that a volume might be filled in the attempt to do justice, by description, to objects so full of suggestive subject for study. THEBIT, 85—(40·8—126·8). A crater about 32 miles in diameter and about 9700 feet deep, devoid of a central cone. It appears on the upper part and near the middle of Plate XIII. The plateau has five minute craters upon it. On the east outside are two small craters, the lesser of which, about 2·75 miles diameter, has a central cone. We specially note this fact, because it is the smallest crater but one in which we have detected a central cone: no doubt, however, many smaller craters possess this unmistakable stamp of true volcanic origin, but so minute are the specks of light which the central cones of such very small craters reflect, that they fail to be visible to us. East of Thebit is a very remarkable straight cliff 60 miles long by about 1000 feet high, called by some observers the “Railway,” and apparently the result either of an upheaval or of a down-sinking of the surface of the circular area across whose diameter it stretches. Under moderate magnifying power, this cliff appears straight, but with higher power and under favourable conditions, its face is seen to be serrated, and along the upper edge may be detected several very minute craters. A more conspicuous small crater is seen at the north end of the cliff. To the east of the cliff nearly opposite the centre are two craters, from the east side of the larger of which proceeds a fine crack parallel to the cliff and passing through a dome-shaped hill of low eminence. PLATO, 210 (41·8—81·8). Plate XIV.