The Moon. 201 



The grey interior plain contains many irregularities of 

 surface, of which the principal is a crater called Picard, at least 

 twenty-one miles in diameter. Twenty-one miles ! what a 

 scale this gives the lunar student in gazing at this marvellous 

 landscape ! A spectator stationed here would see the earth 

 like a great globe, between three and four times of the ap- 

 parent size of the moon to us, standing at an elevation of about 

 34° in its W.S.W. sky, passing through all the varied phases 

 of the moon, and only shifting its place a little in consequence 

 of libration. The sun, on the contrary, reaches 74° to 77° of 

 altitude at noon, and the interior hollow is for 12 Oh. a shadow- 

 less and, as we should suppose, an oppressively burning basin. 

 It is surrounded by a tint somewhat darker than that of the rest 

 of the plain, above which its W. wall ascends 3050 feet, but 

 5300 above the bottom of the crater. Schroter has given the 

 latter at least 3000 feet more, but no measures can be trusted 

 taken under so unfavourable an angle. The smaller craters, 

 Picard A and B, are steeper and deeper, and retain almost all 

 their shadow when it is quitting their more imposing neighbour. 

 Within the line of the E. coast lie several high mountains, 

 either isolated or connected by low ridges, as is frequently 

 observed in the moon. These are so ill-represented in the 

 great map of B. and M. that they have given a special drawing 

 with the letter-press, full of minute detail. Like all their 

 delineations towards the limb, it suifers materially in effect 

 from the attempt to represent both sides of every mountain as 

 in a bird's-eye view, when one side only is visible in per- 

 spective. It would not, indeed, have been practicable to 

 avoid this, while persevering consistently in the conventional 

 style adopted in maps ; but the result is unfavourable in all 

 situations lying obliquely to the eye. Independently however 

 of this awkwardness, for which the observer must learn to 

 make allowance, I am obliged to remark that I cannot succeed 

 in reconciling it with what I have seen in the same region, and 

 have roughly indicated in the accompanying diagram. One of 

 these mountains which B. and M. have designated e (affixing the 

 letter, however, in their large map not to the proper object, but 

 to a mountain about f° N.N.W.), terminates a low serpentine 

 ridge running up from the crater Picard d, and contains, beneath 

 its summit (the loftiest point in the neighbourhood,* 5500 feet 

 above its W. base), a distinct crater, first represented by 

 Cassini ; of the existence of this there is no question : but its 

 W. is so much higher, broader, and brighter than its B. wall 



* Schroter however rates it differently. He gives it 4982 feet, but thinks 

 some of its neighbours higher. I have also noticed it not casting the longest 

 shadow ; but in this there is much uncertainty, for want of an uniformly level 

 base. 



