PICO, 211 (41·9—87·3). Plate XIV. This is one of the most interesting examples of an isolated volcanic “mountain of exudation,” and it forms a very striking object when seen under favourable circumstances. Its height is upwards of 8000 feet, and it is about three times as long at the base as it is broad. The summit is cleft into three peaks, as may be ascertained by the three-peaked shadow it casts on the plain. Five or six minute craters of very perfect form may be detected close to the base of this magnificent mountain. There are several other isolated peaks or mountains of the same class within 30 or 40 miles of it which are well worthy of careful scrutiny, but Pico is the master of the situation, and offers a glorious subject for realizing a lunar day-dream in the mind’s eye, if we can only by an effort of imagination conceive its aspect under the fiercely brilliant sunshine by which it is illuminated, contrasted with the intensely black lunar heavens studded with stars shining with a steady brightness of which, by reason of _our_ atmosphere intervening, we can have no adequate conception save by the aid of a well-directed imagination. TYCHO, 30 (43·0—142·3). Plate XVI. This magnificent crater, which occupies the centre of the crowded group in our Plate, is 54 miles in diameter, and upwards of 16,000 feet deep, from the highest ridge of the rampart to the surface of the plateau, whence rises a grand central cone 5000 feet high. It is one of the most conspicuous of all the lunar craters, not so much on account of its dimensions as from its occupying the great focus of disruption from whence diverge those remarkable bright streaks, many of which may be traced over 1000 miles of the moon’s surface, disregarding in their course all interposing obstacles. There is every reason to conclude that Tycho is an instance of a vast disruptive action which rent the solid crust of the moon into radiating fissures, which were subsequently occupied by extruded molten matter, whose superior luminosity marks the course of the cracks in all directions from the crater as their common centre of divergence. So numerous are these bright streaks when examined by the aid of the telescope, and they give to this region of the moon’s surface such an extra degree of luminosity, that, when viewed as a whole, their locality can be distinctly seen at full moon by the unassisted eye as a bright patch of light on the southern portion of the disc. (See Plate III.) The causative origin of the streaks is discussed and illustrated in Chapter XI.