. NEWS FROM THE MOON. 239 



too slight to warrant any prolonged or exact discussion 

 respecting them. But a few words remain to be said on 

 the question which originated the strange theories 

 devised to explain why the moon at present shows no 

 traces either of oceans or an atmosphere. 



I have said that on our earth the law seems esta- 

 blished that where there is no water there are no 

 volcanoes. May it not be, however, that this law does not 

 extend to the moon ? Mr. Mathieu Williams, whose work, 

 The Fuel of the Sun, has suggested many new and striking 

 considerations respecting the celestial orbs, has brought 

 to bear on this question an experience which very few 

 students of astronomy have possessed the knowledge, 

 namely, of the behaviour of fused'masses of matter cooling 

 under a variety of circumstances. * I have watched 

 the cooling of such masses very frequently,' he says, 

 4 and have seen abundant displays of miniature volcanic 

 phenomena, especially marked where the cooling has 

 occurred under conditions most nearly resembling those 

 of a gradually cooling planet or satellite that is, when 

 the fused matter has been enclosed by a resisting and 

 contracting crust. The most remarkable that I have seen 

 are those presented by the cooling of the " tap cinder " 

 from puddling furnaces. This, as it flows from the 

 furnace, is received in stout iron boxes (called " cinder 

 bogies "). The following phenomena are usually observ- 

 able on the cooling of the fused cinder in a circular 

 bogie. First a thin solid crust forms on the red-hot 

 surface. This speedily cools sufficiently to blacken. 

 If pierced by a slight thrust from an iron rod, the red- 



