The Moon Part 10

RAMSDEN.--This ring-plain, 12 miles in diameter, derives its importance from the remarkable rill-system with which it is so closely a.s.sociated.

Its border, about 1800 feet on the W. above the outside surface, is slightly terraced within on the E., where there is an unrecorded bright crater on the slope. The two princ.i.p.al clefts on the S. originate among the hills E. of Capua.n.u.s. The more easterly begins at a crater on the N.

edge of these objects, and runs N. to the E. side of Ramsden; the other originates at a larger crater, and proceeds in a N. direction up to a bright little mountain S.W. of Ramsden; when, swerving to the N.E., it ends at the W. wall of this formation. This mountain is a centre or node from which three other more delicate branches radiate. On the N., three of the shortest clefts pertaining to the system are easily traceable from neighbouring mountains up to the N. wall, which they apparently partially cut through. The E. pair have a common origin, but open out as they approach the border of Ramsden.

VITELLO.--A very peculiar ring-plain, 28 miles in diameter, on the S.

side of the Mare Humorum, remarkable for having another nearly concentric ring-plain, of considerably less alt.i.tude within it, and a large bright central boss, overlooking the inner wall, 1700 feet in height. The outer wall is somewhat irregular, and is broken by gaps and valleys on the S.

and N.W. It rises on the E. about 5000 feet above the Mare, but only about 2000 above the interior, which includes a crater on its N. side, and some low ridges.

HAINZEL.--This remarkable formation, which is about 55 miles in greatest length, but is hardly half so broad, derives its abnormal shape from the partial coalescence of two nearly equal ring-plains, the walls of both being very lofty,--more than 10,000 feet. It ought to be observed under a morning sun when the floor is about half illuminated. At this phase the extension of the broad bright terraced E. border across a portion of the interior is very apparent, and the true structural character of the formation clearly revealed. The floor abounds in detail, among which, on the S., are some large craters and a bright longitudinal ridge. Hainzel is flanked on the W. and S.W. by a broad plateau, W. of which stand two ring-plains about 15 miles in diameter, both having prominent central mountains and bright interiors.

WILHELM I.--A large irregular formation, about 50 miles across, S.E. of Heinsius, with walls varying very considerably in height, rising more than 11,000 feet on the E., but only about 7000 feet on the opposite side. The border is everywhere crowded with depressions, large and small.

Three ring-plains, not less than 6 miles in diameter, stand upon the S.

wall, the most westerly overlapping its shallower neighbour on the E., which projects beyond the wall on to the floor. The interior has a very rugged and uneven surface, upon the N. side of which are two very distinct craters, and a short crater-row on the W. of them. It is traversed from W. to E. by three bright streaks from Tycho, two on the N.

being very prominent under a high light.

LONGOMONTa.n.u.s.--A much larger walled-plain, S. of the last. It is 90 miles in diameter, with a border much broken by depressions, especially on the N.E. At one peak on this side it rises to the tremendous alt.i.tude of 13,000 feet above the floor, and at peaks on the W. more than 1000 feet higher. There is a crowd of ring-plains on the N.E. quarter of the interior, and some hills and craterlets in other parts of it. It is also crossed by rays from Tycho.

SCHILLER.--A fine lozenge-shaped enclosure, with a continuous but somewhat irregular border. It is about 112 miles in extreme length, and rather more than half this in breadth. The loftiest section of the wall is on the W., where it rises 13,000 feet above a considerably depressed interior. There is a bright crater on this side and some terraces. On the broad inner slope of the E. border, the summit ridge of which is especially well-marked, there is a large shallow depression. The floor contains scarcely any detail, except some ridges on the N. side and a few craterlets. The great bright plain E. of Schiller and the region on the S.E. are especially worthy of scrutiny under a low morning sun.

BAYER.--This object, 29 miles in diameter, with a terraced border rising on the W. to a height of 8000 feet above the floor, is so closely a.s.sociated with Schiller, that it may almost be regarded as forming part of it. A long lofty mountain arm, apparently connected with the W. wall of the latter, runs from the E. side of Bayer towards the N.W. There is a crater on the E. side of the interior.

ROST.--An oblong-shaped ring-plain, 30 miles in diameter, on the S.W. of Schiller, with moderately high walls, and, according to Neison, a shallow depression within, nearly central. I have seen a crater shown by Schmidt on the E. side of the floor. A valley runs from the E. side of Rost to the S. of Schiller.

WEIGEL.--A not very conspicuous ring-plain on the S. of Schiller, with a crater on its N.W. rim, and a larger ring adjoining it on the S.E. A prominent curved mountain arm from the E. wall of Schiller runs towards the N. side of this formation.

BLANCa.n.u.s.--A formation, 50 miles in diameter, on the S.E. side of Clavius, whose surpa.s.sing beauties tend to render the less remarkable features of this magnificent ring-plain and those of its neighbour Scheiner less attractive than they otherwise would be. The crest of its finely terraced wall, which at one peak on the E. rises to 18,000 feet, is at least 12,000 feet above the interior. Krieger saw twenty craters on the floor (1894, Sept. 21, 13h.), most of them situated on the S.

quarter.

SCHEINER.--A still larger object, being nearly 70 miles in diameter, with a prominently terraced wall, fully as lofty as that of Blanca.n.u.s. There is a large crater, nearly central, two others on the N.E. side of the floor, and a fourth at the inner foot of the E. wall. There is also a shallow ring on the N.E. slope. Schmidt shows, but far too prominently, two straight ridges crossing each other on the S. side of the central crater.

CASATUS.--A large walled-plain, about 50 miles in diameter, S.E. of Blanca.n.u.s, near the limb, remarkable for having one of the loftiest ramparts of all known lunar objects; it rises at one peak on the S.W. to the great height of 22,285 feet above the floor, while there are other peaks nearly as high on the N. and S. The wall is broken on the E. by a fine crater. There is also a crater on the N.W. side of the very depressed floor, together with some craterlets.

KLAPROTH.--Casatus partially overlaps this still larger but less ma.s.sive formation on its S.E. flank. The walls of Klaproth are much lower and very irregular and broken, especially on the W. There are some ridges on the floor. The neighbouring region is covered with unnamed objects, large and small.

EAST LONGITUDE 40 deg. TO 60 deg.

FLAMSTEED.--A bright ring-plain, 9 miles in diameter, in a barren region in the Ocea.n.u.s Procellarum, N.E. of Wichmann. It has a regular border (broken at one place on the N. by a gap, which probably represents a crater), rising to a height of about 1400 feet above the surrounding plain. A great enclosure, 60 miles in diameter, lies on the N. of Flamsteed. It is defined by low ridges which exhibit many breaks, though under a high light the ring is apparently continuous. Within are several small craters and two considerable hills, nearly central.

HERMANN.--A ring-plain, about 10 miles in diameter, in the Ocea.n.u.s Procellarum, W. of Lohrmann. It is a.s.sociated with a group of long ridges, running in a meridional direction and roughly parallel to the coast-line.

LETRONNE.--A magnificent bay or inflexion in the coast-line of the Ocea.n.u.s Procellarum, N.N.E. of Ga.s.sendi, presenting an opening towards the N. of nearly 50 miles, and bounded on the S. and S.W. by the lofty Ga.s.sendi highlands. Its border on the W., about 3000 feet high, is crowned with innumerable small depressions. The interior includes four bright little mountains, nearly central (three of them forming a triangle), a bright crater on the W. side, and several minor elevations and ridges. On the plain N. of the bay, is a large bright crater, from which a fine curved ridge runs to the central mountains. If Letronne is observed under oblique illumination, the low mounds and ridges on the Mare outside impress one with the idea that they represent the remains of a once complete N. wall.

BILLY.--A ring-plain, 31 miles in diameter, S.E. of Letronne, with a very dark floor, depressed about 1000 feet below the grey surface on the W., and a regular border, rising more than 3000 feet above it. There is a narrow gap on the S., and indications of a crater on the N.W. rim. Two small craters stand on the S. half of the interior. The formation is flanked on the S.W. by highlands.

HANSTEEN.--A somewhat larger ring-plain, with a lower and more irregular rampart, rising on the W. to nearly 3000 feet above the floor, which is depressed to about the same extent as that of Billy.

Both the inner and outer slopes are terraced on the E., where the _glacis_ is traversed by a short, delicate, rill-like valley.

There are some bright curved ridges on the floor. On the W. of Billy and Hansteen is a wide inlet of the Ocea.n.u.s Procellarum, bounded by the Letronne region on the W., and on the S. by lofty highlands. On the surface, not far from the S.W. border of Hansteen, is a curious triangular-shaped mountain ma.s.s, with a digitated outline on the S., and including a small bright crater on its area. Between this and the ring- plain is a large but somewhat obscure depression, N. of which lies a rill-like object extending from the N. point of the triangular mountain to the W. wall. At the bottom of a gently sloping valley between Billy and Hansteen is a delicate marking, which seems to represent a cleft connecting the two formations.

ZUPUS.--A formation about 12 miles in diameter with a dark floor, situated in the hilly region N.E. of Mersenius.

FONTANA.--A noteworthy ring-plain, about 20 miles in diameter, E.N.E. of Zupus, with a bright border, exhibiting a narrow gap on the S. and two large contiguous craters on the N.W. The faint central mountain stands on a dusky interior. On the N. is a large peculiar depressed plain with a gently sloping wall, within which are three short rill-like valleys and a crater.

MERSENIUS.--With its extensive rill-system and interesting surroundings, one of the most notable ring-plains in the third quadrant. It is 41 miles in diameter, and is encircled by a fine rampart, which on the side fronting the Mare Humorum rises 7000 feet above the floor, which is distinctly convex, and is depressed 3000 feet below the region on the E., though it stands considerably above the level of the Mare. The prominently terraced border is tolerably regular on the N.W., but on the S. and S.E. is much broken by craters and depressions, the largest and most conspicuous interrupting the continuity of its summit-ridge on the latter side. A fine crater-row traverses the central part of the interior, nearly axially, and a delicate cleft crosses the N. half of the floor from the inner foot of the N.E. wall to a crater not far from the opposite side. I detected another cleft on November 11, 1883, also crossing the N. side of the floor.

South of Mersenius is the fine ring-plain Mersenius _d_, about 20 miles in diameter, situated on the border of the Mare; and, extending in a line from this towards Vieta are two others (_a_, and Cavendish _d_,), somewhat larger, but otherwise similar; the more easterly being connected with Cavendish by a mountain arm. One of the princ.i.p.al clefts of the system (all of which run roughly parallel to the N.E. side of the Mare, and extend to the Percy Mountains E. of Ga.s.sendi) crosses the floor of _d_, and, I believe, partially cuts into its W. wall. Another, the coa.r.s.est, abuts on a mountain arm connecting _d_ with Mersenius, and, reappearing on the E. side, runs up to the N.W. wall of the other ring- plain, _a_, and, again reappearing on the E. of this, strikes across the rugged ground between _a_ and Cavendish _d_, traversing its floor and border, as does also another cleft to the N. of it. Cavendish _d_ includes a coa.r.s.e cleft on its floor, running from N. to S., which I have frequently glimpsed with a 4 inch achromatic. There are two other delicate clefts running from the Ga.s.sendi region to the S.W. side of Mersenius, which are in part crater-rills.

CAVENDISH.--A notable ring-plain, 32 miles in diameter, S.E. of Mersenius, with a prominently terraced border, rising at one point on the S. to a height of 6000 feet above the interior, on which are a few low ridges. A large bright ring-plain (_e_), about 12 miles in diameter, breaks the continuity of the S.E. wall, and adjoining this, but beyond the limits of the formation, is another smaller ring with a central hill.

There is also a bright crater on the N.W. border. The W. _glacis_ is very broad, and includes two large shallow depressions. An especially fine valley runs up to the N. wall, to the W. side of _e_.

VIETA.--One of the finest objects in the third quadrant; a ring-plain 51 miles in diameter, with broad lofty walls, a peak on the west rising to nearly 11,000 feet, and another N. of it to considerably more than 14,000 feet above the interior. It is bounded by a linear border, approximating very closely to an hexagonal shape, which is broken by many gaps and cross-valleys. On the S., the S.W. and S.E. sections of the wall do not meet, being separated by a wide valley flanked on the W. by a fine crater, which has broken down the rampart at this place. The N. border is likewise intersected by valleys and by a crater-row. The inner slopes are conspicuously terraced. There is a very inconspicuous central mountain and several large craters on the floor, some of them double. Ten have been counted on the N. half of the interior. On the S.E. of Vieta are two fine overlapping ring-plains, with a crater on the wall common to both.

DE VICO.--A conspicuous little ring-plain, about 9 miles in diameter, with a lofty border, some distance E. of Mersenius.

LEE.--An incomplete walled-plain, about 28 miles in diameter, on the S.

side of the Mare Humorum, E. of Vitello, from which it is separated by another partial enclosure, with a striking valley, not shown in the published maps, running round its W. side. If viewed when its E. wall is on the morning terminator, some isolated relics of the wrecked N.W. wall of Lee are prominent, in the shape of a number of attenuated bright elevations separated by gaps. Within are three or four conspicuous hills.

DOPPELMAYER.--Under a high sun this large ring-plain, 40 miles in diameter, resembles a great bay open to the N.W., without a trace of detail to break the monotony of the surface on the side facing the Mare Humorum. When, however, it is viewed under oblique morning illumination, a low broad ridge is easily traceable, extending across the opening, indicating the site of a ruined wall. There is an isolated mountain at the S.W. end of this, which casts a fine spire of shadow across the floor at sunrise. The interior contains a ma.s.sive bright central mountain and several little hills. The crest of the wall on the E. is much broken.

FOURIER.--A large ring-plain, 30 miles in diameter, S.W. of Vieta, with a border rising at a peak on the W. more than 9000 feet above the floor, There are two craters on the outer slope of the N.W. wall, a prominent crater on the S. wall, and (according to Schmidt) a small central crater on the floor, which I have not seen. In the region between Fourier and Vieta there are three ring-plains, two (the more westerly) standing side by side, and on the W., towards the Mare, are two others much larger, that nearer to Fourier being traversed by one cleft, and the other by two clefts, crossing near the centre of the floor.

CLAUSIUS.--A small bright ring-plain in an isolated position N.W. of Schickard, with a crater both on its N. and S. rim, and a faint central hill.

LACROIX.--A ring-plain 20 miles in diameter, N. of Schickard. It has a prominent central mountain.

SCHICKARD.--One of the largest wall-surrounded plains on the visible surface of the moon, extending about 134 miles from N. to S., and about the same from E. to W., enclosing a nearly level area, abounding in detail. Its border, to a great extent linear, is very irregular, and much broken by the interposition of small ring-plains and craters, and on the N. by cross-valleys. Its general height is about 4000 feet, the loftiest peak on the W. wall rising to more than 9000 feet above the floor. The inner slopes of this vast rampart are very complex, especially on the E., where many terraces and depressions may be seen under suitable illumination. There are three large ring-plains in the interior, all of them S. of the centre; and at least five smaller ones near the inner foot of the E. wall, which can only be well observed when libration is favourable. The two more easterly of the large ring-plains are connected by a cleft, and there are several short clefts and crater-rows a.s.sociated with the smaller ring-plains. On the N. side of the area is a number of minute craters. The floor is diversified by two large dark markings--an oblong patch on the S.W. side, ab.u.t.ting on the wall, being the more remarkable; and a dusky area, occupying a great portion of the N. part of the floor, and extending up to the N. border. This is traversed by a light streak running from N. to S., which is the site of a row of minute craters.

LEHMANN.--A ring-plain, about 28 miles in length, on the N. of Schickard, with which it is connected by a number of cross-valleys.

DREBBEL.--A bright ring-plain, 18 miles in diameter, on the N.W. of Schickard, with a lofty irregular border (especially on the W.), exhibiting a well-marked terrace on the E., a distinct gap on the N., and a small crater on the S.E. rim. On a dusky area between it and Schickard stand three prominent deep craters.

PHOCYLIDES.--This extraordinary walled plain, with its neighbouring enclosures, is structurally very remarkable and suggestive. It consists of a large irregular formation, with a lofty wall, flanked on the N. by a smaller and still more irregular enclosure (_b_), the floor of which is 1500 feet above that of Phocylides, the line of part.i.tion being a high cliff, probably representing a "fault," whose shadow under a low sun is very striking. Phocylides is about 80 miles in maximum length, or, if we reckon the small enclosure _b_ to form a part of it, more than 120 miles.

The loftiest peak, nearly 9000 feet, is on the W. border, near the part.i.tion wall. The continuity of the rampart is broken on the S. by a large crater. There is a bright ring-plain on the W. side of the floor, and a few small craters. Phocylides _b_ has only a solitary crater within it. Phocylides C, ab.u.t.ting on the W. flank of Phocylides, is about 26 miles in diameter. Its somewhat dusky interior is devoid of detail, but the outer slope of its W. wall is crowded with a number of minute craters, which, under good conditions, may be utilised as tests of the defining power of the telescope used. Phocylides A, on the bright S.W.

plain, is a large deep crater with a fine crater-row flanking it on the W.

WARGENTIN.--A most remarkable member of the Phocylides group, flanking the S.E. side of Schickard. Unlike the majority of lunar formations, its floor is raised considerably above the surrounding region, so that it resembles a shallow oval dish turned upside down. It is 54 miles in diameter, and, except on the S.W. (where it abuts on Phocylides _b_, and for some distance is bounded by its wall), it has only a border of very moderate dimensions. On the N.E. slope of this ghostly rampart I have seen a distinct little crater, and two much larger depressions on the N.W. slope. There are some low ridges on the floor, radiating from a nearly central point, which have been aptly compared to a bird's foot.

SEGNER.--A fine ring-plain, 46 miles in diameter, on the S.E. side of Schiller, with a linear border on every side except the N. At a peak on the W., whose shadow is very remarkable, it rises to a height of more than 8000 feet above the outer surface. There is a crater on the S.W.

wall, another on the N.W. wall, and several depressions on the outer slope on this side. The central mountain is small but conspicuous. A large unnamed enclosure extends N. of Segner: it is larger than Schiller, and is surrounded by a lofty barrier. The bright plain between this and the latter is worth examination under a low sun.

ZUCHIUS.--Is situated on the S.E. of Segner, which it slightly overlaps.

It is very similar in size and general character, and has a lofty terraced wall, rising at one place on the W. to nearly 11,000 feet above the floor. A very fine chain of craters, well seen when the opposite border is on the morning terminator, runs round the outer W. slope of the wall. There is a bright crater beyond this on the S.W. Zuchius has a central peak.

BETTINUS.--Another ring-plain of the same type and size, some distance S.

of the last, with a ma.s.sive border, terraced within, and rising on the W.

more than 13,000 feet above the floor, on which stands a grand central mountain, whose brilliant summit is in sunlight a long time before a ray reaches any part of the deep interior.

KIRCHER.--A ring-plain, about 45 miles in diameter, S. of Bettinus, remarkable also for its very lofty rampart, which on the S. attains the tremendous height of nearly 18,000 feet above the floor, which appears to be devoid of detail.