Smithsonian Report, 1928. — Barrell 



Plate 1 



The Full Moon 



In the telescope the directions are reversed, south appearing above and north below. The maria 

 are the dark plains covering about half of the hemisphere. The Mare Imbrium is seen as a great 

 circular plain, over COO miles in diameter, in the northeast quadrant. To the left of it lie the Maria 

 Serenitatis, Tranquilitatis, and Fecunditatis in order. Below the last is the isolated Mare Crisium. 

 Just south of Imbrium the large brilliant spot with irregular rays is the crater Copernicus. To the 

 south of Copernicus is the Mare Nubium. Still farther south is the crater Tycho, from which 

 radiates the most brilliant ray system of the moon. One ray may be traced across the Mare Sereni- 

 tatis, fully one-third of the way around the globe. These ray systems give a pattern of intersecting 

 lines somewhat similar to the "canal" systems of Mars, but here on the moon are clearly developed 

 by purely physical actions. (Photograph by Yerkes Observatory) 



