Lunar Details. 375 



being' bounded by a line joining the centres of Manilius and 

 Eratosthenes, its S. extending as far as Schroter (of B. and M.). 

 The direction is about E. by S., and the streaks are parallel, 

 and show no tendency to converge to Copernicus." — Oct. 20. 

 The dark streakiness was " more intermixed with light stripes, 

 which seem to be the streaks of Copernicus ; in fact, the ap- 

 pearance, judging from to-night, may be due to the gradually- 

 increasing visibility of those streaks coming up into sight with 

 the higher illumination, through a smoky, brownish-grey 

 surface. As observed last night, these streaks in the S. part 

 of the surface in question do not point to the centre of 

 Copernicus." Oct. 22, 4d. 2h. after First Quarter. "Dark 

 streakiness seems now, in a very changed aspect, with great 

 preponderance of light, to show an admixture in its S. portion 

 of the streams of Kepler with those of Copernicus ; the former 

 seeming to pass by the S. side of the ring of Copernicus, and, 

 of course, to be subsequently parallel to its streams. There is 

 an evident crossing and interference of the two systems, as if 

 they had not been contemporaneous, but the one had burst 

 through the other." 1855, Dec. 29, 2d. 4h. before Last 

 Quarter. Mare Vaporum : " the streakiness not remarkable, 

 as in the increasing Moon." 



1855, Oct. 19 (as before). Dark tracts nea,r Sinus JEstuum. 

 The equatorial region is ' ' strikingly marked by three undefined 

 spots of a brownish-grey of considerable extent, having a 

 smoky aspect. The first is the slope of the Apennines S. of 

 Huygens, especially where it borders the Sinus JEstuum by a 

 gentle and slightly- elevated circular sweep ; the second is 

 apparently a rough surface of no great height, extending 

 from T (B. and M.) N. of Schroter to the E. side of that 

 crater; the third is a mass of low hillocks beneath the S.W. 

 foot of Copernicus. Besides these, and divided from the second 

 by a lighter surface, is a small dark tract, consisting, I believe, 

 of two portions, and so represented by B. and M., N. of Y 

 (above)." These spots are all fairly traceable in the great 

 map. 1867, Nov. 7. 9|-inch silvered reflector; terminator a 

 little beyond Gassendi (64). The three dark spots of 1855, 

 Oct. 19, very fairly made out, though illumination very much 

 more advanced : the third seems to be the Rhceticus of Biccioli, 

 very distinct and dark ; but if the dark spot divided by a light 

 streak S.W. of Copernicus in B. and M. is meant for this, as it 

 appears, it is not well laid down ; too small, and too far N". 

 The " small dark tract of two portions" appears of a more 

 complex form : the W., which is a pretty regular ellipse in 

 B. and M. is now divided in half by a narrow brighter 

 streak pointing S.W. — the E. is deeply indented from N.E. in 

 the same direction by a broader and more obvious stream. 



