96 
POPULAR SCIENCE REVIEW, 
trast being very marked in the red and yellow, and less so in the violet ; it 
showed, however, no lines or bands other than those seen in other parts. 
The spectrum of the polar spot and its neighbourhood were very bright from 
about D to F, but showed very little red ; the north limb, on the contrary, 
gave a spectrum somewhat less bright in the green and yellow, but extending 
further into the red. The group round 0 seemed to be darker over ‘ Dawes’ 
Continent ’ (the bright spot north of 1 Dawes’ Ocean ’) and less dark on the 
north limb. Bands a and B were seen, but no difference in their appearance 
from whatever part of the disc was examined ; but being fainter thanC, a slight 
difference was less likely to be detected.” u On September 21 and 26, the 
absorption bands then measured were noticed to be very slightly fainter in 
the limb than anywhere else. The locality where they were most distinct 
was variously estimated as from 5" to 6" from the limb on September 21, 
and from 3" to 4" on September 26 ; as the definition was much better on 
the latter occasion the smaller estimation is more likely to be correct. The 
difference in intensity, except just on the limb, was exceedingly slight ; but 
the point where the bands were estimated to be darkest was always found 
to be at the same distance from the limb.” This points unmistakably, as it 
seems to us, to the conclusion that the whiteness near the limb results from 
the condensation of aqueous vapour into the form of visible cloud. “ The 
red end of the spectrum of Mars was much fainter on or near the limb ; but 
the violet seemed of the same intensity from all parts of the disc, and was 
visible about as far as in the spectrum of the moon. The observations were 
made by Mr. Maunder.” 
Mr. Green’s drawings of Mars must be regarded as taking the place which 
has heretofore been accorded to Mr. Dawes’ drawings of the planet. They 
certainly far surpass all yet taken in accuracy as well as in fulness of detail. 
He used a 13-inch silver-on-glass reflector, by With, and a fine 12^-inch 
speculum, by Messrs. Horne & Thornthwaite. Each drawing was made 
direct from the telescope, and entirely independent of those which had been 
produced previously, all comparison being reserved till the evening was over. 
In one region (that lying east of the De la Rue Ocean, in Proctor’s chart — see 
our number for July, 1877) several important corrections have been made. 
In particular, the sea to which Mr. Proctor gave the name of Lockyer Sea, is 
shown to be far more strongly marked than the one to the north, called 
Dawes Sea. The narrow inlet connecting Lockyer Sea with De la Rue 
Ocean in Mr. Dawes’ drawings has no real existence. Under unfavourable 
atmospheric conditions there appears to be an inlet ; but when the definition 
is good the appearance is found to be due to the presence of a small lake 
lying in the line of the supposed connection. 
“ It has been remarked,” says Mr. Green, “ that the snow caps do not 
agree exactly with the poles of the axis of revolution. It may be a confir- 
mation of this statement to mention that by September 18, the snow zone,” 
which a week before had appeared large and distinct, “ was considerably 
reduced in size, and its outline very indefinite, whereas by the end of the 
month it had returned in great measure to its previous form and size ; the 
rapidity and extent of this change being greater than could be attributed to 
simple alterations of temperature.” 
An amusing episode occurred after the reading of Mr. Green’s paper at the 
