I ought to mention that the writer from whom I have quoted says that all the photographs were examined and the different objects in this region identified within forty-eight hours of the time when Dr. Klein's letter reached England. He mentions also that he has himself personally examined them. Doubtless at that time the exact position of the supposed new crater was not known. By the way, it is strange, considering that the name Louis Rutherfurd is distinctly written in large letters upon the magnificent photograph in question, that a selenographer who has carefully examined that photograph should spell the name Rutherford. He must really not assume, when on re-examining the picture he finds the name spelled Rutherfurd, that there has been any change, volcanic or otherwise, in the photograph. In conclusion I would point out that another of these laborious crater-counters, in a paper recently written with the express purpose of advocating a closer and longer-continued scrutiny of the moon, makes a statement which is full of significance in connection with the subject of lunar changes. After quoting the opinion of a celebrated astronomer, that one might as well attempt to catalogue the pebbles on the sea-shore as the entire series of lunar craters down to the minutest visible with the most powerful telescope, he states that while on the one hand, out of thirty-two thousand eight hundred and fifty-six craters given in Schmidt's chart, not more than two thousand objects have been entered in the Registry he has provided for the purpose (though he has been many years collecting materials for it from all sides); on the other hand, "on comparing a few of these published objects with Schmidt's map, it has been found _that some are not in it_,"--a fact to which he calls attention, "not for the purpose of depreciating the greatest selenographical work that has yet appeared, but for the real advancement of selenography." Truly, the fact is as significant as it is discouraging,--unless we are presently to be told that the craters which are not common to both series are to be regarded as new formations. RICHARD A. PROCTOR, _in Belgravia_. FOOTNOTES: [63] To some this may appear to be a mere truism. In reality it is far from being so. If two globes of equal mass were each of the same exact temperature throughout, they might yet have very unequal total quantities of heat. If one were of water, for instance, and the other of iron or any other metal, the former would have far the larger supply of heat; for more heat is required to raise a given weight of water one degree in temperature, than to raise an equal weight of iron one degree; and water in cooling one degree, or any number of degrees, would give out more heat than an equal weight of iron cooling to the same extent. RECOLLECTIONS OF THACKERAY.