Systems of Rays on the Moon's Surface

IT is a strange fact that those who have little experience of volcanoes notice a rough resemblance between the irregularities of the lunar surface and terrestrial volcanic vents. However much one juggles with diminished gravity and magnifies volcanic energy in the past history of our satellite, there are still several facts which are overlooked by many theorists. Mr. C. H. Plant points out in NATURE of January 15 (p. 550) that the “olcanic action of the moon was of enormous character”—this would need be so to produce on such a small globe craters of 80 kilometres or more in diameter.