468 KANSAS CITY REVIEW OF SCIENCE. 



craters lie on the summits of pretty steep cones. When Stadius emerges from 

 the lunar night, these "crater-cones" are revealed in immense numbers, like 

 thorns stuck in the ground ; but as they are all small and low, the shadows quick- 

 ly disappear under the ascending Sun, and then the darkness only of the crater 

 itself can be seen. 



These formations appear to have a close relationship to our volcanoes; but I 

 would, by the way, turn the attention of selenographers, and of geologists also, 

 to another class of forms on the Moon's surface, which appear to me to corre- 

 spond in a still greater degree to our volcanic formations, and which up to the 

 present time are little known or not at all. The only selenographer who has 

 paid attention to these forms is Julius Schmidt in Athens. He first saw some of 

 these formations in January and February of 185 1. " In a southwesterly direction 

 from Theophilus," he says, in his explanatory volume to his large map of the 

 Moon, "there lie in the Mare two small dark patches, like imperfect half-shaded 

 craters ; they remain visible as dark patches under a high altitude of the Sun. 

 The western one is the larger," This remark dates from January, 1851 : oh the 

 25th day of February of the same year Schmidt perceived close to Copernicus, 

 and in a southwesterly direction towards Gambart, "a bright point surrounded 

 by a dark grey nimbus, which lies in the grey plain." In the year 1873, Schmidt 

 returned to these formations and found that there is present in them a white 

 cavity, which at times appears like a crater. Among the numerous lunar forms 

 Avhich can be descried with the strong telescopes of the present time, and which I 

 estimate at 200,000, those described above are so rare that I could only reckon 

 five which show the type with certainty and two in which it is also very probably 

 present. 



Without being aware of Schmidt's observations, I had come upon the above 

 mentioned very rare formations in the course of my researches on the Moon's sur- 

 face. I perceived that the two objects in the neighborhood of Theophilus are 

 craters with clear white cavities, which, at a certain distance on the outside, were 

 surrounded by a ring of smoky grey material. In the course of my observations 

 it gradually became manifest that the larger of the two craters fell away external- 

 ly like an unusually flat cone, so that the base of this cone, which had a very 

 moderate vertical height, yet spread itself several miles wide. Upon the highest 

 point of this very flat base stands the precipitous cone of eruption. Radiating 

 from the crater numerous hills or folds run out upon the gentle declivity, and be- 

 tween them appear tiny little craters which parasitically cover the slopes of the 

 base in great numbers. The dark grey material is deposited only in the neigh- 

 borhood of the white-colored principal crater, round about its precipitous cone, 

 and indeed within a narrow, pretty sharply limited, circular zone. The smaller 

 crater to the northwest exhibits similar conditions, yet I have not been able to 

 perceive in it the radiating hills and the little parasitic craters. 



Since last autumn these two craters have not generally been so plainly visible 

 as in former years; indeed I cannot at present perceive the crater proper, but see 

 only a grey patch within the dark ring. In the crater mentioned by Schmidt 



