1901.] LOWKLL — SUPPOSED SIGNALS FROM MARS. 175 



1 6. The first thing that appears from the tables is that the observa- 

 tions cannot be satisfied by the supposition of one cloud alone on 

 either day. It is necessary-to suppose two on each occasion, a high 

 cloud followed by a much lower one. The height of the lower 

 cloud was about three to four miles, and it lay to the west and 

 north of the main one. 



The eastward end of the main cloud on December 7 was in lati- 

 tude 4 . 7, longitude 333 ; its westward end in latitude 3°.6, longi- 

 tude 339 . So that the cloud either stretched this distance or 

 moved over it in the interval. From the great speed required it is 

 unlikely that the cloud actually travelled this distance in this time. 

 If translation took place at all, it was probably the translation of 

 propagation. But, from the phenomena of the next night, it would 

 seem more likely that the cloud really stretched over 6°, or 220 

 miles. Its breadth was j4 thread or o".oq, which is forty-five 

 miles. 



The dimensions of the subsidiary cloud, or subsidiary portion of 

 the main cloud, are much more conjectural. It would seem to have 

 been of about the same extent as the main body. 



On December 8 the main cloud was slightly less long but broader 

 than it had been on the preceding night ; the subsidiary patch was 

 not much changed. But both clouds had in the interval drifted 

 1 7 to the eastward and 3 or so to the north. Whether, therefore, 

 the clouds were being propagated or not in a west-by-north direc- 

 tion each night, it would seem that either they or the stratum of 

 air which generated them was drifting east by north at the rate of 

 1 7 -f- in twenty-three and a half hours, or at the rate of twenty- 

 seven miles an hour. 



17. Looking back now, with this motion in mind, in the records 

 of the 1 2th December, § 1 r, we find that the place the clouds should 

 have occupied on that date (longitude centre 302 — 31 7 ), if the 

 same translation had been kept up, was under careful observation 

 for such phenomena and nothing whatever was seen. Indeed, so 

 comprehensive in extent were the observations, that any less speed 

 of translation should also have caused the clouds to fall within the 

 limits of inspection, and even a somewhat greater speed should 

 have done so too. 



On the 13th the place they should have reached was scrutinized. 

 The observations covered from longitude centre 280 to 208 . 

 Nothing showed. The same was done on the 15th, longitude 

 centre 2 76°-285°. 



