The Lunar Clefts — Mare Vaporum. 



101 



but omitted by B. and M. ; it is about 4- the diameter of the 

 larger crater. The projecting cusp on the right-hand was on 

 the latter occasion very luminous. The two small craters E. 

 and W. of Hyginus are larger 

 than as shown in L. or B. and 

 M. : when sketched, the one 

 was all bright, the other par- 

 tially in shade. The bending 

 of the cleft does not take place 

 in Hyginus, as shown by L., 

 but in or near the latter crater. I have no note of any other 

 crater W. of Hyginus, but I carry the cleft further than B. 

 and M., turning it, like L., with a bend more S. towards the 

 site of Agrvppa b, and then again bending it W. and carrying 

 it on as a very minute- line across the N. slope of Agrippa, at 

 a considerable distance from the ring. B. and M. may have 

 seen part of this as the long bank shown (but a little too far 

 N.) in our diagram. 



The second great cleft I have seen bordered in all its length, 

 though less distinctly in the portion E. of Silberschlag, by a 

 narrow faint shadow parallel to it on the S., as though on that 

 side at least it had an elevated margin.* I have drawn it as 

 commencing on the N. side of Ariadceus a. Three times it has 

 appeared to me interrupted by the narrow ridge W. of /3, which 

 it divides in B. and M. I have never seen /3 nor a divided by 

 it ; as to a, on the other (E.) side of Silberschlag , I am less con- 

 fident. I may have mistaken it for the ridge N. a little W. of 

 Silberschlag, by which, like Schr., I have seen the cleft entirely 

 intercepted. It has not appeared to me to pass close to the 

 crater opposite Silberschlag as in B. and M., but at a little 

 distance, as in Schr. and L., and the bend at this place is 

 greatly exaggerated by B. and M. The semi-crater form of 

 Schr.'s D I have plainly made out. A little E. of this spot it 

 sends off a very distinct branch to the S.E., which apparently 

 forms a communication with the W. end of the Hyginus cleft, 

 somewhat N". of the point where the latter carries on a branch, 

 already noticed, across the N. slope of Agrippa. I have no 

 note of the small crater at the E. end of this cleft, but I have 

 remarked a very faint narrow dark line continued on from near 

 that spot still further E., towards the end of the Hyginus cleft. 



These minutise may be of some interest as showing the 

 multiplicity and intricacy of these cracks, and as aids to further 

 study; but the most curious remains to be specified. 1861, 

 April 1 7, I perceived that the part of the cleft between a and jS 



* With the great Northumberland Telescope, at Cambridge, aperture 11J in., 

 Breen has seen both banks very plainly, alike in valley and mountain, and has 

 noticed them stretching a short distance into the dark part of the disc. 



