IS THE MOON A DEAD PLANET? 569 



accessible to most astronomers, and are hence but imperfectly known. 

 The inquiry, we are told, is one of great difficulty, requiring a thor- 

 ough acquaintance with several branches of science. The results ar- 

 rived at by prolonged, minute, and careful observation of the details 

 of the lunar formation are rejected because the proofs on which they 

 rest are not well understood. 



The most prominent instance of supposed lunar change on the sur- 

 face of the moon is that of the crater Linne. On the northwest quad- 

 rant of the moon, near the centre of a level tract about 430 miles in 

 diameter, there is a bright crater called Bessel, nearly 14 miles in di- 

 ameter, with a circular wall rising 4,000 feet above the interior, and 

 about 1,600 feet above the surrounding plain. Scattered over this plain 

 are a few small craters, some 2^ miles in diameter, with walls about 

 300 feet high. Near its eastern centre an eminent selenographer 

 named Lohrman placed a distinct, bright crater about five miles in diam- 

 eter, which he described as being, after Bessel, the most conspicuous 

 object on this great tract of level ground. Ten years later, our great- 

 est selenographer, Baron von Madler, confirmed Lohrman's observa- 

 tions, and made this crater a subject of special study, naming it 

 Linne. In the drawings of Schmidt, who was about this time making 

 lunar observations of this particular part of the moon, Linne is shown 

 as a deep crater corresponding with the descriptions of Lohrman and 

 Madler. 



In October, 1866, when Linne was in a position to be most con- 

 spicuous, Schmidt was startled by finding no trace of the deep, wide 

 crater, but only a faint cloud marking about five miles in diameter. 

 Schmidt at once announced the circumstance, and nearly every astron- 

 omer in Europe turned his attention to the spot. But Linne has never 

 since been seen of the size and character given it by Lohrman, Mad- 

 ler, and Schmidt. This large crater unquestionably no longer exists. 

 Powerful telescopes reveal, in its place, a white, cloudy marking con- 

 taining a small crater-cone with an opening scarcely one-twentieth the 

 size of the former crater. 



The reason why astronomers will not admit the reality of any 

 change in Linne* is, first, a strong prejudice against the possibility of 

 such change ; and, second, the fact that Schroter, of Lillienthal, the 

 earliest of the great selenographers, in one of his first drawings, 

 made November 5, 1788, with low powers, does not draw Linne as a 

 crater. Near its place he draws a white spot on a ridge marked V, 

 and a larger spot marked G. Schmidt took this white spot to be 

 Linne, a view strongly urged by Huggins, and accepted as correct by 

 astronomers. They say, as Schroter's drawing is not unlike the pres- 

 ent appearance of Linne, Lohrman, Madler, and Schmidt, must have 

 been mistaken as to what they thought they saw. Again, in a map 

 made by Lahire in the seventeenth century, no trace of Linne can be 

 found. It may be said, however, that all the maps of this period 



