32 report — 1859. 



XVI. (a*) A small crater which is situated upon the northern extremity of a ridge 

 (not the ribbon 15), as manifested by the morning and evening illuminations. This 

 ridge does not exhibit any reflective powers different from those of the surrounding 

 land. 



XVII. (11) The outlines of an obliterated crater with its darker floor and some- 

 what lighter rim than the space (12). No indications of any hypsometrical relations 

 of this crater are met with morning and evening, so that it would appear to have been 

 filled up. It is a somewhat difficult object to see, and requires good definition. 



XVIII. (12) A space of nearly the same uniformity of tint as (4) between Geminus 

 (a*) and (B). It is rather darker towards the ribbon. 



XX f 141 I ^ wo sma " somewnat l'g' nt s P ots > tne y do not a PP ear to be craters. 



XXI. (15) A dark ribbon-like band extending from Burckhardt to Geminus, skirting 

 the eastern margin of Geminus and proceeding towards (a*). 



This dark ribbon is not in any way elevated above the general lunar surface, as no 

 shadow is perceptible either in the morning or evening ; in fact it disappears entirely 

 under these illuminations. It is clearly a " ground mark " exhibiting differing degrees 

 of intensity. 



Contemplating the drawing as it lies before us, we see at a glance that during the 

 four days (moon's age 10 to 14) we are dealing in this part of the moon with markings 

 of the surface only. This conclusion is particularly forced upon us by the remark- 

 able phenomena presented by Geminus. The depth of this crater, as well as the 

 elevation of its walls, are well brought out by light and shadow, especially in the fore- 

 noon illumination, but as the day advances the crater- form is lost; in fact such is 

 the metamorphosis the crater undergoes, that only a portion (the northern) is recog- 

 nizable, and this more by the curved outline and narrow stripe across, than by any- 

 thing else. Between the dark ribbon (15) and the dark space north of Bernoulli (6), 

 including the dark-floored Bernoulli itself, a space of somewhat uniform breadth 

 extends. This space, which is of a lighter tint than either of the narrower stripes 

 bounding it east and west, is crossed by a brighter space (7), which passing over 

 Geminus, converges to the crater (B) in the southern margin of Messala. This 

 brighter space is not peculiar to the locality between the two narrow darker fringes ; 

 it extends considerably to the eastward of Geminus, passes near to a crater marked 

 by Beer and Madler (A), and is connected with the system of brilliant stripes radia- 

 ting from the brilliant crater Proclus. The narrow stripe (8), which is rather brighter, 

 belongs to the same class as (2), (3), and (9), and may be seen crossing Geminus on the 

 eighth day of the moon's age, both northern and southern walls being apparent ; it 

 consequently traverses alike elevation and hollow. It would appear (assuming for a 

 moment that the bright space (7) existed anterior to the production of the crater, an 

 assumption by the by for which there are no reasonable grounds) that that produc- 

 tion had not in the least degree influenced the reflective powers of those parts of the 

 surface on which the crater is situated. On the other hand, assuming that both 

 brighter and darker tints resulted from some change after the crater was produced, it 

 is difficult to see how the complete obliteration of the southern part should be effected 

 at the same time that its elevated wall remains. That the wall is not materially 

 interfered with, is evident from the fact that both wall and depression come out in 

 strong relief with the evening shadows. 



It is very possible that the crater might have been produced when the entire area 

 between the two dark fringes reflected light similarly, and that its southern wall with 

 its step or terrace only presented phenomena of light and shade when the morning 

 and evening incidences were such as to bring them out from hypsometrical inequality. 

 The narrow stripe (S) across is evidently posterior in age to the crater itself, and 

 may or may not be contemporaneous with the production of the lighter area con- 

 verging to Messala ; and from the distinct and well-marked manner in which the 

 north-western rim is cut off at the junction of the lighter and darker areas, it would 

 appear that this brighter rim is also of later origin. 



The bright crater (C) deserves a passing remark. On consulting Beer and Madler's 

 map, it will be seen that Burckhardt is situated nearly midway between it and the 

 bright crater marked (A) in Cleomedes, from which a similar stripe extends to 

 Burckhardt. A question here suggests itself. Is Burckhardt at a lower level than 



