SURFACE CHARACTERS OF THE PLANET MARS. 253 



two months, and then later than was expected ; at first indistinct and 

 dim, but becoming more distinct on the following day. This was one 

 month after the autumnal equinox of Mars. The doubling continued 

 to be visible until after the end of February. On the 11th of January 

 another doubling had already made its appearance, but was not further 

 noticed because the canals which doubled were very irregular. Great, 

 therefore, was our surprise to find that, on the 19th of January, a canal 

 which passed through the center showed two straight parallel lines, 

 which, on repeated examination, were found to be true phenomena. 

 From this date the number of canals appearing doubled increased ; 

 even on the 24th of February when the apparent diameter of Mars had 

 been reduced to less than 10, the doubling of the canals could be dis- 

 tinguished. In an aggregate (exclusive of a few cases which could 

 not be configured on account of the insufficient power of the telescope 

 to define such delicate cases), some twenty cases of doubling were 

 noticed, seventeen of which occurred in the course of one month, i. e., 

 from January 19th to February 19th the mean of the time corre- 

 sponding to about the end of the second month after the autumnal 

 equinox of the planet. In addition to these there were probably oth- 

 ers which made their appearance ; but, unfortunately, the unfavorable 

 weather and the increasing distance of the planet prevented a success- 

 ful following up of the further development of these highly important 

 phenomena. In a few cases it was possible to determine some pre- 

 monitory signs of the doubling. 



On January 13th a very light and indefinite shadow began to 

 spread itself parallel to the canal known as "Ganges" ; on the 18th 

 and 19th these portions were covered with white spots, on the 20th 

 the Ganges appeared to be composed of two lines, but the phenomenon 

 was still doubtful ; on the 21st the doubling was distinct and remained 

 so until February 23d. Similar observations were made on other lines. 



Everything leads to the conclusion that we have here a periodical 

 phenomenon, which is probably connected with the seasons of Mars. 

 If this be the case, we may hope to extend these observations during 

 the next opposition, when we shall be able to see the seasons of the 

 planet advanced about eighty days. This opposition will take place 

 January 1, 1884. The position of Mars on this date will be identical 

 with that on the 13th of February, 1882, and the apparent diameter 

 will be about 12 , 9 /r , that is, pretty near the mean diameter which the 

 planet had during the finding of the above - described doublings. 

 Therefore there is reason to hope that these phenomena may again be 

 determined and confirmed by other observers. The desire to obtain 

 such information has been the main object of the foregoing communi- 

 cation. 



