534 THE POPULAR SCIENCE MONTHLY. 



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 cov- 

 ering it with a double-refracting crystal. To this phenomenon, which 

 has no analogy, M. Schiaparelli has given the name of the gemi- 

 nation of canals ; and he has prepared a full memoir respecting it, 

 which will shortly appear. 



Although they were met at first with incredulity, these astonish- 

 ing discoveries have received and are receiving constant confirmation 

 from the observations of such men as Boeddicker and Burton in Ire- 

 land, 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 inter- 

 est. 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 modi- 

 fications 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 inter- 

 prets the designs of Schroeter and finds in them a trace of many of 

 M. Schiaparelli's details. Pere Lamey has also made many observa- 

 tions of Mars, which have led him to some original conclusions worthy 

 of investigation. Translated for the Popular Science Monti hly from 

 La Nature. 



