The writer from whom I have already quoted is naturally (being a selenographer) altogether unwilling to accept the conclusion that this spot is the crater floor as photographed (not as seen) under a somewhat higher illumination than that under which the floor of the crater appears dark. There are several white spots immediately around the dark crater, he says: "which of these is the particular white spot which the author" (myself) "assumes I did not see?" a question which, as I had made no assumption whatever about this particular writer, nor mentioned him, nor even thought of him, as I wrote the article on which he comments, I am quite unable to answer. But he has no doubt that I have "mistaken the white spot" (which it seems he can identify, after all) "for Klein's crater, which is many miles farther north, and which never does appear as a white spot: he has simply mistaken its place." I have waited, therefore, before writing this, until from my own observation, or from a drawing carefully executed by Dr. Klein, I might ascertain the exact place of the new crater. I could not, as it turned out, observe the new crater as a black spot myself, since the question was raised; for on the only available occasion I was away from home. But I now have before me Dr. Klein's carefully drawn map. In this I find the new crater placed not nearly, but _exactly_ where Rutherfurd's crater appears. I say "Rutherfurd's crater," for the white spot is manifestly not merely a light tinted region on the darker background of the Sea of Vapours (as the region in which the crater has been found is called): it is a circular crater more than two miles in diameter; and the width of the crescent of shadow surrounding its eastern side shows that in March 1865, when Rutherfurd took that photograph, the crater was not (for its size) a shallow one, but deep. Now, it is quite true that, to the eye, under high illumination, the floor of the crater does not appear lighter than the surrounding region; at least, not markedly so, for to my eye it appears slightly lighter. But everyone knows that a photograph does not show all objects with the same depth of shading that they present to the naked eye. A somewhat dark green object will appear rather light in a photograph, while a somewhat light orange-yellow object will appear quite dark. We have only to assume that the floor of the supposed new crater has a greenish tinge (which is by no means uncommon) to understand why, although it is lost to ordinary vision when the Sea of Vapours is under full illumination, it yet presents in a photograph a decidedly lighter shade than the surrounding region.