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 distinguished. 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 corresponding to about the end of the second month after the autumnal equinox of the planet. In addition to these there were probably others which made their appearance; but, unfortunately, the unfavorable weather and the increasing distance of the planet prevented a successful following up of the further development of these highly important phenomena. In a few cases it was possible to determine some premonitory 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", 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 communication.
