Landsberg. E. of Landsberg, four light-surrounded craters, forming with Landsberg A (in the Second Quadrant) an interesting group. Lohrmann A. A light-surrounded crater, with a light area a few miles N. of it. S. lat. 1 deg., E. long. 61 deg. Euclides. Has a conspicuous nimbus with traces of rays, a typical example. Guerike. There is a crater, with nimbus, W. of this, in E. long. 12 deg., S. lat. 11 deg. 5 min. Parry. A very brilliant light-spot in the S. wall. Parry A. Surrounded by a bright nimbus. Alpetragius B. A conspicuous light-surrounded crater, one of the most remarkable on the moon. Alpetragius _d_ (E. long. 11 deg., S. lat. 13 deg. 8 min.). A bright spot, seen by Madler as a crater, but which, as Schmidt found in 1868, no longer answers to this description. Mosting C. A light-surrounded crater. Lalande. Has a large nimbus and distinct rays. Hell. A large ill-defined spot in E. long. 4 deg., S. lat. 33 deg. This is most probably the site of the white cloud seen by Cassini. Mercator. There is a brilliant crater and light area under E. wall. FOURTH QUADRANT. Stevinus _a_. A crater E. of Stevinus; it is a centre of wide extending rays. Furnerius A. Prominently light-surrounded, with bright streaks, radiating for a long distance N. and S. Messier A. The well-known "Comet" rays, extending E. of this. Langrenus. Has a large but very pale ray-system. It is best seen under a low evening sun. Three long streaks radiate towards the E. from the foot of the _glacis_ of the S.E. wall. Censorinus. A very brilliant crater with faint rays. Theophilus. The central mountain is faintly light-surrounded. Madler. This ring-plain and the neighbourhood on the N. and N.W., include many bright areas and curious streaks. Almanon. About midway between this and Argelander is a very brilliant little crater. Beaumont. Between this and Cyrillus stand three considerable craters with nimbi. Cyrillus A. A prominent light-surrounded crater. Alfraganus. A light-surrounded crater with rays. POSITION OF THE LUNAR TERMINATOR Though the position of the Lunar Terminator is given for mean midnight throughout the year in that very useful publication the Companion to the Observatory, it is frequently important in examining or comparing former drawings and observations to ascertain its position at the times when they were made. For this purpose the subjoined tables (which first appeared in the Selenographical Journal) will be found useful, as they give for any day between A.D. 1780 and A.D. 1900 the selenographical longitude of the point where the terminator crosses the moon's equator, which it does very nearly at right angles. [Tables and examples] LUNAR ELEMENTS Moon's mean apparent diameter - 31 min. 8 sec. Moon's maximum apparent diameter - 33 min. 33.20 sec. Moon's minimum apparent diameter - 29 min. 23.65 sec. Moon's diameter, in miles - 2163 miles. Volume (earth's = 1) - 1/49.20 or 0.02033. Mass (earth's = 1) - 1/81.40 or 0.0128.