Light Spots in the Lunar Night. 55 



of Mont Blanc in that direction sinks into the plain ; and by 

 finding another well-known crater (Plato K. of B. and M.), 

 not quite so small, lying a little way out in the plain in the 

 prolonged direction of the Wedge-shaped Valley (Int. Ob$., ix. 

 61), not only somewhat enlarged, but doubled by the encroach- 

 ment of a smaller companion on its S.E. side — a feature quite 

 new to him, though he had drawn it twice under entirely 

 dissimilar illumination, with the interval of a year. Besides 

 this, though the weather was not favourable, several other very 

 small objects were perceived for the first time within a short 

 distance, while a known minute crater in the plain, S.E. of Mont 

 Blanc, could scarcely be identified as such.* He was naturally 

 much surprised at all this, in a spot which he had 16 times during 

 half a year been scrutinizing under various illuminations with 

 especial care ; and while holding to his idea that many such 

 apparent changes were connected with variations in a lunar 

 atmosphere, he thought that on the whole, taken in connection 

 with the luminous appearance in this very region, some eruptive 

 action might probably be indicated. 



The site of this phosphorescence, so to speak, naturally 

 attracted his continued attention ; but never could he trace a 

 vestige of it again. He waited for the time when the moon 

 should occupy a corresponding position, which happened more 

 than a year afterwards, 1789, Oct. 15. The circumstances 

 were very favourable : the old features were all discernible, 

 and even a very faint shining could be made out on the site of 

 Proclus, but where- the little star-like speck had vanished, the 

 gazing of an hour brought out so feeble a trace of a glimmering 

 point at times, that it was quite uncertain, and probably only 

 the illusory result of an over-taxed vision. Had the little 

 crater at the E. foot of Mont Blanc been subsequently found 

 of larger size, he might, he says, have referred this flicker to 

 the closing scene of an eruption there. But in this he would 

 have been mistaken. The maps of B. and M. and Lohrmann 

 do not contain it, and I do not recollect to have ever seen it. 

 However, 1832, Apr. 9, I made out distinctly, with only 3 

 inches of a Barlow achromatic, the double crater Plato K, and 

 suspected a similar companion to a little crater near at hand, 

 half way between it and the wall of Plato (designated Plato i 

 by B. andM). This suspicion was converted into a certainty 

 with a 3-,V inch aperture, 1836, May 25, when I was struck 

 with the curious aspect of the two adjacent pairs, and made a 

 note that " this object surely could not have escaped Schr/s 

 observations had it existed in his time." We learn something 



* At another time he saw this as a hill, and curiously enough it is so repre- 

 sented in the maps of Lohrmann andB. and M. The " Sections" of the former 

 do not extend to this region. 



