United States or Mongolia ? Vote for the TOP Country of the Week !


T. G. Elger, the celebrated English selenographer, says of Plinius that, at sunrise, "it reminds one of a great fortress or redoubt erected to command the passage between the Mare Tranquilitatis and the Mare Serenitatis." But, of course, the resemblance is purely fanciful. Men, even though they dwelt in the moon, would not build a rampart 6,000 feet high!

Most observers will agree with Schmidt, that observations and drawings of objects on the sombre depressed plains of the moon are easier and pleasanter to make than on the dazzling highlands, and that the lunar "sea" is to the working selenographer like an oasis in the desert to the traveller a relief in this case, however, not to an exhausted body, but to a weary eye.

CLEFTS OR RILLS. Though Fontenelle, in his Entretiens sur la Pluralite des Mondes, informs his pupil, the Marchioness, that "M. Cassini discovered in the moon something which separates, then reunites, and finally loses itself in a cavity, which from its appearance seemed to be a river," it can hardly be supposed that what the French astronomer saw, or fancied he saw, with the imperfect telescopes of that day, was one of the remarkable and enigmatical furrows termed clefts or rills, first detected by the Hanoverian selenographer Schroter; who, on October 7, 1787, discovered the very curious serpentine cleft near Herodotus, having a few nights before noted for the first time the great Alpine valley west of Plato, once classed with the clefts, though it is an object of a very different kind.

The eminent selenographer, the late W.K. Birt, compared many of them to "inverted river-beds" from the fact that, as often as not, they become broader and deeper as they attain a higher level. The branches resemble rivers more frequently than the main channels; for they generally commence as very fine grooves, and, becoming broader and broader, join them at an acute angle.

Some of the large craters present the same appearance. Barbicane knew this opinion of the German selenographer, an opinion shared by Boeer and Moedler. Observation has proved that right was on their side, and not on that of some astronomers who admit the existence of only gray on the moon's surface.

Although the attempt to bring all these bizarre forms under a rigid scheme of classification has not been wholly successful, their structural peculiarities, the hypsometrical relation between their interior and the surrounding district, their size, and the character of their circumvallation, the dimensions of their cavernous opening as compared with that of the more or less truncated conical mass of matter surrounding it, all afford a basis for grouping them under distinctive titles, that are not only convenient to the selenographer, but which undoubtedly represent, as a rule, actual diversities in their origin and physical character.

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 coarser, on the S.

According to him, the colour common to the vast plains, known under the name of "seas," is dark grey, intermingled with green and brown. Some of the large craters are coloured in the same way. Barbicane knew this opinion of the German selenographer; it is shared by Messrs. Boeer and Moedler.

They are very plentifully distributed round the margin and in other parts of the former, which includes besides one of the longest and loftiest on the moon's visible surface the great serpentine ridge, first drawn and described nearly a hundred years ago by the famous selenographer, Schroter of Lilienthal.