432 [Feb. 12, 



From the author's sketches, three, representing opposite hemi- 

 spheres, and one intermediate quadrature, have been selected for 

 engraving, one central to the assumed meridian of or 360, the 

 others to the meridians of 90 and 180 nearly. See figs. 1, 2, 3. 



Fig. 1. Mars as seen on the 27th of September and on several other occasions till 

 the 13th of December. (Longitude 0.) 



On considering the surface of the planet, either as seen in the 

 telescope, or delineated on paper, we feel in some doubt as to the 

 meaning of what we see. Are the bright parts (often seen of a red 

 tint) land, the darker parts (often appearing of a greenish grey) 

 water? or, as in the moon, are the reflecting powers of different 

 parts of a dry surface very unequal? Is there any considerable 

 change in the aspect of the masses or boundaries between one epoch 

 and another, so as to indicate atmospheric vicissitudes like those 

 on Jupiter and our own planet ? 



Taking the latter question first, the author found, on the experience 

 of his observations during 74 days, that no material change took 

 place in the main and prominent features about the longitude which 

 he marks 0. Not that after this considerable interval the appear- 

 ances remained exactly as at first : that was not, and could not be 



