118 FROM NEBULA TO NEBULA 



ready obvious, that the moon is devoid of seas be- 

 cause it does not rotate. In critically examining the 

 great dark splotches on the lunar surface, \ve cannot 

 fail to believe that they are the emptied beds of former 

 oceans. But if so. what has become of the water that 

 once filled them? To this question Dr. Johnston Stoney 

 has siloes ted an answer. According to the molecular 

 theory of matter, the atoms, or molecules, or electrons, 

 as the case may l>e, are believed to acquire tremendous 

 speeds, which vary with the several elements, the mole- 

 cules of hydrogen (which is one of the essential chemi- 

 cal components of water) for instance, being capable 

 of higher velocities than perhaps those of any other 

 terrestrial element. Of course there is no way of 

 proving this conclusion, and after all it may be. only 

 another speculation. But assuming it to be true, Dr. 

 Stoney has the distinction of being the first to indicate, 

 as a logical sequence, the probable escape of hydrogen 

 from bodies of small size, like Mars and the moon, and 

 their consequent dearth of seas. Another supposition 

 is that the water has percolated down through the vol- 

 canic crevices to interior hollows. 



It may be set down as well established that there 

 is very little humidity in the moon's atmosphere, and 

 that the latter too is exceedingly rare. It is also a 

 fact that the moon's surface gravity is only one-sixth 

 that of our planet. Taking these three things together, 

 it can be shown that any water there may be on the 

 lunar surface would evaporate freely at about 50 F. 



Paradoxical as it may sound, the real surface of 

 the moon is as smooth as that of Mars. Equally para- 

 doxical may ring the statement that the lunar oceans 

 have risen from their beds, and taken up their perma- 

 nent abode on the dry land, hi plain English, then hare 

 disappeared, not into outer space but into SNOW,, and 



