52 Light Spots in the Lunar Night. 



of the moon, he picked up from time to time faint glowing" 

 specks, and was at much pains to identify them, and to detect 

 the cause of their apparent variations, and after a first precipitate 

 inference of volcanic activity, was at length led to the impor- 

 tant conclusion, that portions of the lunar surface subtending 

 only a few seconds, may be either entirely inconspicuous, or 

 faintly luminous, or strongly glittering, according to the angle 

 of illumination, and that consequently a distinct luminosity may 

 be sometimes perceived in a spot in the earth-shine, which has 

 but a dusky aspect even under the solar rays falling on it at a 

 different angle. The effect therefore of the earth's reflection is 

 directly comparable only with the aspect of the full moon; 

 and so far, there would be no reason to ascribe any other origin 

 than the reflection of the earth-shine, to the generality of the 

 luminous specks visible on the dark hemisphere. And in this 

 conclusion Bode and other astronomers acquiesced. There 

 were, however, some residual phenomena not thus entirely 

 explained, and Schroter thought that not only had atmospheric 

 differences to be allowed for in the usual way, but also their 

 indirect action in influencing the reflective power of the earth, 

 and that beyond this, there must be some modifying cause on the 

 surface of the moon or in her atmosphere, to account for certain 

 variations which he perceived. Without anticipating some of 

 his observations on the neighbourhood of the E. limb, we may 

 give his example, that after a familiar acquaintance of two years 

 with the aspect of Manilius and Menelaus under doubly re- 

 flected light, when he usually found Menelaus considerably the 

 larger and brighter of the two, in a subsequent set of six obser- 

 vations in 1790, Manilius appeared to him not only larger, but 

 at least as bright, and in some instances actually brighter than 

 its neighbour. As to the latter part of these inferences, 

 astronomers may entertain different opinions ; and some would 

 claim an allowance for more practised ocular judgment, such 

 as has been known to influence progressive estimates of the 

 brightness of nebulas or the distances of double stars. But 

 there is always something interesting and instructive in follow- 

 ing the mental processes of any clear and consecutive thinker, 

 who is not afraid of describing his own successive impressions 

 or of retracting his too hasty conclusions. And besides this, 

 facts are often gradually evolved out of seeming confusion and 

 misapprehension, and sometimes what has been suffered to 

 drop through, in hastily grasping at some tempting simplicity 

 of explanation, has been subsequently found essential to the 

 full apprehension of a truth more complex than it may have 

 appeared. It is not impossible that the present very interesting- 

 investigation into the state of the crater Linne, which we owe 

 to the great observer Julius Schmidt of Athens, may lead to a 



