BRITISH ASSOCIATION. 55 



RESEARCHES ON THE MOON. — BY PROF. PHILLIPS. 



The author having on previous occasions presented his views as to the method* 

 and objects of research in the moon, -was desirous now to state a few results, and 

 exhibit a few drawings, the fruit of recent examinations of the moon by means of 

 a*new equatorial by Cooke, with an object-glass of 6 inches. In sketching ring 

 mountains, such as Theophilus and Posidonius, the author has been greatly inter- 

 ested by the changes of aspect which even a small alteration in the angles of ele- 

 vation and azimuth respectively produce in the shadows and lights. Taking aa 

 example from Cyrillus, with its rocky interior, and fixing attention on the nearly 

 central mountain, it always appears in the morning liglit to have two principal un- 

 perforated masses. By a slight change in the direction of the light, the division 

 of these masses is deeply shaded on the north or deeply shaded on the south, and 

 the figure of the masses, i. e., the limit of light and shade, seems altered. A slight 

 change in the angle of elevation of the incident light makes more remarkable dif- 

 ferences. On Posidonius, which is a low, nearly level plateau, within moderately 

 raised borders, the mid-morning light shows with beautiful distinctness the shield- 

 like disc of the mountain, with narrow broken walls, and in the interior, broad, 

 easy undulation one large and several smaller craters. In earlier morning more 

 craters appear and the interior ridges gather to form a broken terrace subordinate 

 to the principal ridge. This circumstance of an interior broken terrace, under the 

 high main ring of mountain, is very frequent, but it is often concealed by the 

 shadow of the great ridge in early morning shadows. To see it emerge into half- 

 lights, and finally to distinct digitations and variously directed ridges, as the light 

 falls at increasing angles, is a very beautiful sight. But it is chiefly to the varia- 

 tions in the central masses of lunar mountains and their physical bearings that the 

 author wishes to direct attention. Many smaller mountains are simply like cup» 

 set in saucers, while others contain only one central or several dispersed cupa. 

 In Plato is a nearly central very small cup, bright, and giving a distinct shadow 

 on the grey ground, as seen by Mr. Lockyer, Mr. Birt, aud Prof. Phillips himself. 

 But in the centre of many of the larger mountains, as Copernicus, Gassendi and 

 Theophilus, is a large mass of broken rocky country, 5,000 or 6,000 feet high, with 

 buttresses passing off into collateral ridges, or an undulated surface of low ridges 

 and hollows. The most remarkable object of this kind which the author has yet 

 observt d with attention is in Theophilus, of which mountain two drawings are 

 given, in which the author places equal confidence, except that the latter drawing- 

 may have the advantage of more experience. The central mass is seen under 

 powers of 200—400 (the best performance is from 200 to 300), and appears as a 

 large conical mass of rocks about fifteen miles in diameter, and divided by deep 

 chasms radiating from the centre. The rock-masses between these deep clefts are 

 bright and shining, the clefts widen towards the centre, the eastern side is more 

 diversified than the western, and like the southern side has long excurrent but- 

 tresses. As the light grows on the mountain, point after point of the mass on the 

 eastern side comes out of the shade, and the whole figure resembles an uplifted 

 mass which broke with radiating cracks in the act of elevation. Excepting in 

 steepness, this resembles the theoretical Mont d"Or of De Beaumont; and as there 

 is no mark of cups or craters in this mass of broken ground the author is disposed 

 to regard its origin as really due to the displacement of a solidified part of the. 



