274 



Lunar Perspective. 



each other. 4th. On the S.W. of Plato is a mountain range 

 projecting from the mountainous border of the crater. This 

 mountain range is the highest in the immediate neighbourhood, 

 its shadow being the last to be observed on the surface outside 

 the S.W. rim of Plato. 



The drawing of Fig. 4 was made in 1863, at London, on 



N 

 Fig. 4. 



July 6, 18 to 15 hours, G.M.T. The telescope used was the 

 Koyal Astronomical Society's Sheepshank's, No. 5, aperture 

 2*75 inches, power 150. This drawing is also under the 

 evening illumination, but the moon had not attained her 

 greatest libration ; nevertheless, objects were north and east of 

 their mean places. The moon's latitude was about 4 o, 40 / North, 

 so that Plato was removed further from the eye, and conse- 

 quently its elliptic form was narrowed. The libration in longi- 

 tude having carried objects further east, Fig. 2 is differently 

 circumstanced to Fig. 1. The prominent features in Fig. 1 

 are, however, well recognized in Fig. 2. 1st. The bright interior 

 of the W. and S.W. wall, but rather differently illuminated. 

 2nd. The indented shadow of the E. wall. This feature 

 presents a great difference in the two drawings — the crag, or 

 tongue, which projects inwards from the N.B. in a S.E. direc- 

 tion in Fig. 1 is wanting in Fig. 2, and the shadows are not so 

 broad, the difference between the epoch of observation, and 

 that of sunset, being greater in Fig. 2 than in Fig. 1. 3rd. 

 The formation on the north was not drawn, except the mountain 

 range forming its west border, which, in Fig. 2, is straight, 

 instead of being curved, as in Fig. 1. A few objects are given 

 in Fig. 2 on the N.W. not in Fig. 1. Of these, the north edge 

 of Plato, the mountain and crater in a line with it, and the 

 south edsre of the crater on the east, were ascertained to be 



