The Moon Part 7

BIANCHINI.--A fine ring-plain, about 18 miles in diameter, on the N.E.

side of the Sinus Iridum, surrounded by the lofty mountains defining the border of the bay. Its walls, which are prominently terraced within, rise about 7000 feet on the E., and about 8000 feet on the W. above the floor, which includes a prominent ridge and a conspicuous central mountain.

There is a distinct crater on the S. wall, not shown in the maps. Between this side of the formation and the bay is a number of hills running parallel to the sh.o.r.e-line: these, with the intervening valleys, will repay examination at sunrise.

MAUPERTUIS.--A great mountain enclosure of irregular shape, about 20 miles in diameter, in the midst of the Sinus Iridum highlands, N. of Laplace. The walls are much broken by pa.s.ses, and the interior includes many hills and ridges.

CONDAMINE.--A rhomboidal-shaped ring-plain, about 23 miles in diameter, N. of Maupertuis, with lofty walls, especially on the E., where they rise some 4000 feet above the interior. There are three large depressions on the outer N.W. slope, and at least three minute craters on the crest of the wall just above. Though neither Neison nor Schmidt draw any detail thereon, there is a prominent ridge on the N. side of the floor, and a low circular hill on the S. On the S.E. four long ridges or spurs radiate from the wall, and on the N.E. are three remarkable square-shaped enclosures. On the edge of the Mare Frigoris, N.W. of Condamine, are many little craters with bright rims and a distinct short cleft, running parallel to the coast-line. The winding valleys in the region bordering the Sinus Iridum, and other curious details, render this portion of the moon's surface almost unique.

BOUGUER.--A bright regular little ring-plain, about 8 miles in diameter, N. of Bianchini.

J.F.W. HERSCHEL.--A vast enclosed plain, about 90 miles across, bounded on the W. by a mountain range, which here defines the E. side of the Mare Frigoris, on the S. by ma.s.sive mountains, and on the other sides by a lofty but much broken wall, intersected by many pa.s.ses. Within is a large ring-plain, nearly central, and a large number of little craters and crater-pits. The floor is traversed longitudinally by many low ridges, lying very close together, which at sunrise resemble fine grooves or scratches of irregular width and depth.

HORREBOW.--A ring-plain of remarkable shape, resembling the a.n.a.lemma figure, standing at the S. end of the mountain range bounding J.F.W.

Herschel on the W. Schmidt shows a crater on the W. wall, near the constriction on this side, and a second at the foot of the slope of the E. wall.

PHILOLAUS.--A ring-plain 46 miles in diameter, on the N.E. of Fontinelle.

Its bright walls rise on the W. to a height of nearly 12,000 feet above the floor (on which there is a conspicuous central mountain), and exhibit many prominent terraces. Philolaus is partially encircled, at no great distance, by a curved ridge, on which will be found a number of small craters.

ANAXIMINES.--A much foreshortened ring-plain, about 66 miles in diameter, on the E. of Philolaus. One peak on the E. is nearly 8000 feet in height.

Schmidt shows four craters on the W. side of the floor, and a fifth on the S.E. side. There is a bright streak in the interior, which extends southwards for some distance across the Mare Frigoris.

EAST LONGITUDE 40 deg. TO 60 deg.

REINER.--A regular ring-plain, 21 miles in diameter, in the Mare Procellarum, S.S.E. of Marius, with a very lofty border terraced without and within, and a minute but conspicuous mountain standing at the N. end of a ridge which traverses the uniformly dark floor in a meridional direction. A long ridge extends some way towards the S. from the foot of the S. wall, and at some distance in the same direction lie six ill- defined white spots of doubtful nature. On the E.N.E. there is a large white marking, resembling a "Jew's harp" in shape, and farther on, towards the E., a number of very remarkable ridges. On the W. will be found many bright little craterlets. A ray from Kepler extends almost up to the W. wall of Reiner.

MARIUS.--A very noteworthy ring-plain, 27 miles in diameter, in the Ocea.n.u.s Procellarum, E.N.E. of Kepler, with a bright border rising about 4000 feet above the interior, which is of an uneven tone. The rampart exhibits some breaks, especially on the S. The outer slope on the W. is traversed by a fine deep valley, distinctly marked when the opposite side is on the morning terminator. It originates on the S.W. at a prominent crater situated a little below the crest of the wall, and, following its curvature, runs out on to the plain near a large mountain just beyond the foot of the N. border. In addition to the crater just mentioned, there are two smaller ones below the summit of the S. wall, and a small circular depression on the S.E. wall. Mr. W.H. Maw, F.R.A.S., has seen, with a 6 inch Cooke refractor, a bright marking at the N. extremity of the ring, which, when examined with a Dawes' eyepiece, resembled an imperfect crater. The floor includes at least four objects--(1) A crater on the N.W., standing on a circular light area; (2) a white spot a little S. of the centre; (3) a smaller white spot S.E. of this; (4) another, near the inner foot of the S.W. wall. Marius is an imposing object under oblique illumination, mainly because of the number of ridges by which it is surrounded. I have frequently remarked at sunrise that the surface on the W., and especially the outer slope of the rampart, is of a decided brown or sepia tint, similar to that which has already been noticed with respect to Geminus and its vicinity, viewed under like conditions.

Schmidt in 1862 discovered a long serpentine cleft some distance N. of Marius, which has not been seen since.

ARISTARCHUS.--The brightest object on the moon, forming with Herodotus (a companion ring-plain on the E.), and its remarkable surroundings, one of the most striking objects which the telescope has revealed on the visible surface, and one requiring much patient observation before its manifold details can be fully noted and duly appreciated. Its border rises 2000 feet above the outer surface on the W., but towers to more than double this height above the glistening floor. No lunar object of its moderate dimensions (it is only about 29 miles in diameter) has such conspicuously terraced walls, or a greater number of spurs and b.u.t.tresses; which are especially prominent on the S. A valley runs round the outer slope of the W. wall, very similar to that found in a similar position round Marius.

There is also a distinct valley on the brilliant inner slope of the E.

wall, below its crest. It originates at a bright little crater, and is traceable round the greater portion of the declivity. Under a moderately high sun, an oval area, nearly as large and fully as brilliant as the central mountain, is seen on this inner slope. It is bordered on either side by bands of a duskier hue, which probably represent shallow transverse valleys. From its dazzling brilliancy it is very difficult to observe the interior satisfactorily. In addition, however, to the central mountain, there is a crater on the N.W. side of the floor. On the S. side of Aristarchus is a large dusky ring some 10 miles in diameter, connected by ridges with the spurs from the wall, and on the S.E., close to the foot of the slope, is another smaller ring of a like kind.

HERODOTUS.--This far less brilliant but equally interesting object is about 23 miles in diameter, and is not so regular in shape as Aristarchus. Its W. wall rises at one point more than 4000 feet above the very dusky floor. Except on the S.W. and N.E., the border is devoid of detail. On the S.W. three little notches may be detected on its summit, which probably represent small craters, while on the opposite side, on the inner slope, a little below the crest, is a large crater, easily seen. Both the E. and W. sections of the wall are prolonged towards the S. far beyond the limits of the formation. These rocky ma.s.ses, with an intermediate wall, are very conspicuous under oblique illumination, that on the S.W. being especially brilliant. On the N. there is a gap through which the well-known serpentine cleft pa.s.ses on to the floor. Between the N.W. side of Herodotus and Aristarchus is a large plateau, seen to the best advantage when the morning terminator lies a little distance E. of the former. It is traversed by a T-shaped cleft which communicates with the great serpentine cleft and extends towards the S. end of Aristarchus, till it meets a second cleft (forming the upper part of the T) running from the S.E. side of this formation along the W. side of Herodotus. The great serpentine cleft, discovered by Schroter, October 7, 1787, is in many respects the most interesting object of its cla.s.s. It commences at the N. end of a short wide valley, traversing mountains some distance N.E. of Herodotus, as a comparatively delicate cleft. After following a somewhat irregular course towards the N.W. for about 50 miles, and becoming gradually wider and deeper, it makes a sudden turn and runs for about 10 miles in a S.W. direction. It then changes its course as abruptly to the N.W. again for 3 or 4 miles, once more turns to the S.W., and, as a much coa.r.s.er chasm, maintains this direction for about 20 miles, till it reaches the S.E. edge of a great mountain plateau N. of Aristarchus, when it swerves slightly towards the S., becoming wider and wider, up to a place a few miles N. of Herodotus, where it expands into a broad valley; and then, somewhat suddenly contracting in width, and becoming less coa.r.s.e, enters the ring-plain through a gap in the N. wall, as before mentioned. I always find that portion of the valley in the neighbourhood of Herodotus more or less indistinct, though it is broad and deep. This part of it, unless it is observed at a late stage of sunrise, is obscured by the shadow of the mountains on the border of the plateau. Gruithuisen suspected a cleft crossing the region embraced by the serpentine valley, forming a connection between its coa.r.s.e southern extremity and the long straight section. This has been often searched for, but never found. It may exist, nevertheless, for in many instances Gruithuisen's discoveries, though for a long time discredited, have been confirmed. The mountain plateau N. of Aristarchus deserves careful scrutiny, as it abounds in detail and includes many short clefts.

HARBINGER, MOUNTAINS.--A remarkable group of moderate height, mostly extending from the N.W. towards Aristarchus. They include a large incomplete walled-plain about 30 miles in diameter, defined on the W. by a lofty border, forming part of a mountain chain, and open to the south.

This curious formation has many depressions in connection with its N.W.

edge. On the N. of it there is a crater-row and a very peculiar zig-zag cleft. The region should be observed when the E. longitude of the morning terminator is about 45 deg.

SCHIAPARELLI.--A conspicuous formation, about 16 miles in diameter, between Herodotus and the N.E. limb, with a border rising nearly 2000 feet above the Mare, and about 1000 more above the floor, on which Schmidt shows a central hill.

WOLLASTON.--A small bright crater on the Mare N. of the Harbinger Mountains, surpa.s.sed in interest by a remarkable formation a few miles S.

of it, Wollaston B, an object of about the same size, but which is a.s.sociated with a much larger enclosure, resembling a walled-plain, lying on the N. side of it. This formation has a lofty border on the W., surmounted by two small craters. The wall is lower on the E. and exhibits a gap. There is a central hill, only visible under a low sun. About midway between Wollaston and this enclosure stands a small isolated triangular mountain. From a hill on the E. runs a rill valley to the more westerly of a pair of craters, connected by a ridge, on the S.E. of Wollaston B.

MAIRAN.--A bright ring-plain of irregular shape, 25 miles in diameter, on the E. of the Heraclides promontory. The border, especially on the E., varies considerably in alt.i.tude, as is evident from its shadow at sunrise; at one peak on the W. it is said to attain a height of more than 15,000 feet above the interior. There is a very minute crater on the crest of the S. wall, down the inner slope of which runs a rill-like valley. About halfway down the inner face of the E. wall are two other small craters, connected together by a winding valley. These features may be seen under morning illumination, when about one-fourth of the floor is in sunlight. Schroter is the only selenographer who gives Mairan a central mountain. In this he is right. I have seen without difficulty on several occasions a low hill near the centre. The formation is surrounded by a number of conspicuous craters and crater-pits. On the N. there is a short rill-like valley, and another, much coa.r.s.er, on the S.

SHARP.--A ring-plain somewhat smaller than the last, on the E. of the Sinus Iridum, from the coast-line of which it is separated by lofty mountains. There is a distinct crater at the foot of its N.E. wall, and a bright central mountain on the floor. On the N. is a prominent enclosure, nearly as large as Sharp itself; and on the N.E. a brilliant little ring- plain, A, about 8 miles in diameter, connected with Sharp, as Madler shows, by a wide valley.

LOUVILLE.--A triangular-shaped formation on the E. of a line joining Mairan and Sharp. It is hemmed in by mountains, one of which towers 5000 feet above its dusky floor.

FOUCAULT.--A bright deep ring-plain, about 10 miles in diameter, lying E.

of the mountains fringing the Sinus Iridum, between Bianchini and Harpalus. A very lofty peak rises near its N. border, and, according to Neison, it has a distinct central mountain, though neither Madler or Schmidt show any detail within.

HARPALUS.--A conspicuous ring-plain, about 14 miles in diameter, on the N.E. of the last, with a floor sinking 13,000 feet below the surrounding surface. As the cubic contents of the border and _glacis_ are quite inadequate to account for it, we may ask, what has become of the material which presumably once filled this vast depression? Harpalus has a bright central mountain.

SOUTH.--On the W. and S., the boundaries of this extensive enclosure are merely indicated by ridges, which nowhere attain the dignity of a wall.

On the N., the edge of a tableland intersected by a number of valleys define its limits, and on the E. a border forming also the W. side of Babbage. The interior is traversed by a number of longitudinal hills, and includes two bright little heights, drawn by Schmidt as craters.

BABBAGE.--A still larger enclosed area, adjoining South on the E., and containing a considerable ring-plain near its W. border. It is a fine telescopic object at sunrise, the interior being crossed by a number of transverse markings representing ridges. These are very similar in character (but much coa.r.s.er) to those found on the floor of J.F.W.

Herschel. The curious detail on the E. wall is also worth examination at this phase.

ROBINSON.--A bright and very deep little ring-plain, about 12 miles in diameter, on a plateau N. of South. Schmidt shows a crater on the W.

border, and two others at the foot of the N. and E. borders respectively.

ANAXIMANDER.--A fine but much foreshortened ring-plain, 39 miles in diameter, ab.u.t.ting on the E. side of J.F.W. Herschel. It has a large crater on its W. border, which is common to the two formations, and a very prominent crater, both on the S. and N. The barrier on the S.W.

rises to a height of nearly 10,000 feet. Schmidt shows a crater and other details on the floor.

EAST LONGITUDE 60 deg. TO 90 deg.

LOHRMANN.--This ring-plain, with Hevel and Cavalerius on the N. of it, is a member of a linear group, which, but for its propinquity to the limb, would be one of the most imposing on the moon's surface. Lohrmann, about 28 miles in diameter, is surrounded by a bright wall, which, to all appearance, is devoid of detail. Two prominent ridges, with a fine intervening valley, connect it with the N. end of Grimaldi. It has a large but not conspicuous central mountain. On the rugged surface, between the ring-plain and the E. edge of the Ocea.n.u.s Procellarum, lies a very interesting group of crossed clefts, some of which run from N.E. to S.W., and others from N.W. to S.E. Three of the latter proceed from different points in a coa.r.s.e valley extending from W. to E., and cross the ridges just mentioned. They follow a parallel course, and terminate on the S. side of a crater-row, consisting of three bright craters ranging in a line parallel to the coa.r.s.e valley. On the N. side of these objects, and tangential to them, is another cleft, which traverses the W.

and E. walls of Lohrmann, and, crossing the region between it and Riccioli, terminates apparently at the W. wall of the latter formation.

No map shows this cleft, though it is obvious enough; and, when the E.

wall of Hevel is on the morning terminator, the notches made by it in the border of Lohrmann are easily detected. Capt. n.o.ble, F.R.A.S., aptly compares two of the crossed clefts to a pair of scissors, the craters at which they terminate representing the oval handles. On the grey surface of the Mare W. of Lohrmann is the bright crater Lohrmann A, from which, running N., proceeds a rill-like valley ending at a large white spot, which has a glistening l.u.s.tre under a high light.

HEVEL.--A great walled-plain, 71 miles in diameter, adjoining Lohrmann on the N., with a broad western rampart, rising at one peak to a height above the interior of nearly 6000 feet, and presenting a steep bright face to the Ocea.n.u.s Procellarum. There are three prominent craters near its crest, and one or two breaks in its continuity. It is not so lofty and is more broken on the E., where three conspicuous craters stand on its inner slope. The floor is slightly convex, and includes a triangular central mountain, on which there is a small crater. The S. half of the interior is crossed by four clefts: (l) running from a little crater N.

of the central mountain, on the W. side of it, to a hill at the foot of the S.W. wall; (2) originating near the most southerly of the three craters on the inner slope of the E. wall, and crossing 1, terminates at the foot of the W. wall; (3) has the same origin as 2, crosses 1, and, pa.s.sing over a craterlet W. of the central mountain, also runs up to the W. wall at a point considerably N. of that where 2 joins the latter; (4) runs from the craterlet just mentioned to the W. end of 2.

CAVALERIUS.--The most northerly member of the linear chain, a ring-plain, 41 miles in diameter, with terraced walls rising about 10,000 feet above the floor. Within there is a long central mountain with three peaks.

Under a high light the region on the W. is seen to be crossed by broad light streaks.

OLBERS.--A large ring-plain, 41 miles in diameter, near the limb, N.E. of Cavalerius. Though a very distinct formation, it is difficult to see its details except under favourable conditions of libration. It has a large crater on its W. wall, a smaller one on the E., and a third on the N. The floor includes a central mountain, and, according to Schmidt, four craters. He also shows a crater-rill on the W. wall, N. of the large crater thereon. Olbers is the origin of a fine system of light rays.

GALILEO.--A ring-plain, about 9 miles in diameter, N.E. of Reiner, a.s.sociated with ridges, some of which extend to the "Jew's Harp" marking referred to under this formation.

CARDa.n.u.s.--A fine regular ring-plain, about 32 miles in diameter, near the limb N. of Olbers. Its bright walls, rising about 4000 feet above the light grey floor, are clearly terraced, and exhibit, especially on the S.E., several spurs and b.u.t.tresses. There is a fine valley on the outer W. slope, a large bright crater on the Mare just beyond its foot, and a conspicuous mountain in the same position farther north. I have not succeeded in seeing the faint central hill nor the crater N. of it shown by Schmidt, but there is a brilliant white circular spot on the floor at the inner foot of the N.E. wall which he does not show.

KRAFFT.--A very similar object on the N., of about the same dimensions; with a central peak, and a large crater on the dark floor ab.u.t.ting on the S.W. wall, and another of about half the size on the outer side of the W.

border. From this crater a very remarkable cleft runs to the N. wall of Carda.n.u.s: it is bordered on either side by a bright bank, and cuts through the N.W. border of the latter formation. It is best seen when the E. wall of Carda.n.u.s is on the morning terminator.

VASCO DE GAMA.--A bright enclosure, 51 miles in diameter, with a small central mountain. It is a.s.sociated on the N. with a number of enclosed areas of a similar cla.s.s, all too near the limb to be well seen.

SELEUCUS.--A considerable ring-plain, 32 miles in diameter, with lofty terraced walls, rising 10,000 feet above a dark floor which includes an inconspicuous central hill. This formation stands on a ridge extending from near Briggs to the W. side of Carda.n.u.s.

OTTO STRUVE.--An enormous enclosure, bounded on the E. by the Hercynian Mountains, and on the W. by a mountain chain of considerable alt.i.tude, surmounted by three or more bright little rings. On the W. side of the uneven-toned interior, which, according to Madler, includes an area of more than 26,000 square miles, stand four craters, several little hills, and light spots. On the W. is the much more regular and almost as large formation, Otto Struve A, the W. border of Otto Struve forming its E.

wall. This enclosure is bounded elsewhere by a very low, broken, and attenuated barrier. At sunrise the E. and W. walls, with the mountain ma.s.s at the N. end, which they join, resemble a pair of partially-opened calipers. There is one conspicuous little crater on the W. side of the floor; and, at or near full moon, four or five white spots, nearly central, are prominently visible.

BRIGGS.--This bright regular ring-plain, 33 miles in diameter, is situated a short distance N. of Otto Struve A. A long ridge traverses the interior from N. to S. On the E. is another large enclosure, communicating with Otto Struve on the S., and really forming a N.