68 Notes of Observations luith 



than those near the centre. Even the terminator line itself 

 grows manifestly less distinct as it approaches the moon's 

 Hmbs ; an appearance difficult to explain apart from a 

 supposition of a lunar atmosphere of some kind. Yet the 

 Spectroscope appears to negative such a supposition. 



Sped. Arist. — 7th Dec, Spectroscope on Aristarchus shows 

 at same time three spectra — one from central hill, and one 

 from each side of the ring, side by side, brighter than from 

 rest of moon, j&t with no lines indicating incandescence, or 

 additional absorption lines beyond those due to the earth's 

 own atmospheric absorption, as far as I could observe with 

 certainty. 



Earthshine. — 2oth Dec. Terminator on Mare Crisium. 

 Turned on the dark, or rather earth-lit portion of the 

 moon, of which I was surprised to find that the large light- 

 collecting power of the Great Telescope enabled me to 

 distinguish all the chief features, the well marked boundaries 

 of the plains, and the craters down to the middle size. 

 Aristarchus comparatively as bright as ever but no appearance 

 of intrinsic light, a broad bright ray shooting off S.E. by 

 Herodotus. The shadow of the western side of the crater 

 Aristarchus was visible on the floor, and the eastern interior 

 slope was brightly illuminated by the earthshine. Grimaldi 

 and Plato appeared as dark proportionately as at full moon, and 

 indeed all parts appear much the same relatively as at the full_ 

 Copernicus. — Copernicus conspicuous with its system of 

 bright rays divergent — the one which intersects the wall of 

 Lambert precisely the same. 



Rays^. — These rays appear, in fact, of the same brightness, 

 relatively at whatever angle of illumination they are viewed, 

 suggesting shade or tint peculiarity, more than peculiar 

 reflective properties. 



Photometry. — Systematic photometric comparisons at 

 varying angles of illumination would probably bring out 

 interestinar analoo-ies with earth formations. 



Appenines. — The Appenines also come out well in 

 Earthshine and stand up in bold relief — a splendid range. 

 To-night, as on former occasions, I looked long and carefully 

 for Schroeter's supposed twilight-streaks from -the bright 

 cusps of the Moon, but did not see anything to be sure of 

 The blaze of light from the bright portion of the Moon so 

 illuminated the field in the vicinity of the cusps that it is 

 hard to say whether the apparent twilight is or is not real. 



