Page:Popular Science Monthly Volume 31.djvu/550

534 quarto memoir of one hundred and nine pages and six plates, are very interesting.

But it is since this magnificent publication appeared that the author, on the occasion of the opposition of Mars of 1881–'82, was a witness of some marvelous changes which are fully described in a memoir that has not yet appeared, but which M. Schiaparelli has kindly sent me. It appears from these observations, and from others which were made between 1884 and 1886, that Mars is at this moment the theatre of phenomena of stupendous grandeur which will be adequate in a few years to impress profound changes in its aspect. The views taken by M. Schiaparelli show that a number of the channels previously described are doubling, or are being paralleled by similar ones having the same dimensions and directions. The appearance on the new map of the hemisphere is nearly the same, Dr. Terby, an eminent areographer, of Louvain, suggests, as would be produced in the former one by covering it with a double-refracting crystal. To this phenomenon, which has no analogy, M. Schiaparelli has given the name of the gemination of canals; and he has prepared a full memoir respecting it, which will shortly appear.

Although they were met at first with incredulity, these astonishing discoveries have received and are receiving constant confirmation from the observations of such men as Boeddicker and Burton in Ireland, M. Perrotin of the observatory at Nice, and his collaborators, MM. Trepied, Thollon, and Gautier. Other observers, like Messrs. Green, Knobel, and Denning, have not been so fortunate in verifying his facts, but their researches, published in the memoirs of the London Astronomical Society, and in the "Monthly Notices," are full of interest. It adds to the mystery that the gemination seems to be made gradually, though rapidly, and with progressive accentuation. Thus, the canal Nilus, at the junction of the eightieth meridian and parallel 20° north, is paralleled by another canal, which is very faintly marked and hardly visible in the older map. In the new map the two canals have a nearly equal intensity.

By careful comparison of Schroeter's designs, made a century ago, and Herschel's earlier ones, M. Terby has discovered analogous modifications on the Martial surface. Some of them are local enlargements of some of the seas, like that called Kaiser, and other changes in the details of configurations which had been supposed to be fixed. Of similar character is the memoir of M. Van de Sand Baghuyzen, in the "Annals of the Observatory of Leyden," in which the author interprets the designs of Schroeter and finds in them a trace of many of M. Schiaparelli's details. Père Lamey has also made many observations of Mars, which have led him to some original conclusions worthy of investigation.—Translated for the Popular Science Monthly from La Nature.