PLANETESIMAL THEORIES OF TEE BARTERS ORIGIN. 207 



Then with regard to the formation of the planets out of the 

 mass rotating around its central orb, which ultimately became our 

 sun, Ave may perhaps blend the two hypotheses and suppose that 

 various nuclei were formed which ultimately became planets. Then 

 comes in the question of heat. When was heat evolved ? There are 

 two ways by which it might have been produced. Heat may have 

 been produced spontaneously by the closer contact of the original 

 atoms or molecules of the planets, for everyone knows that the closer 

 the atoms or molecules of any substance are driven together the 

 greater the heat is which is evolved. But another means is possible. 

 We have recently had evidence of the way in which a gaseous world 

 can become suddenly ignited. Some two or three years ago there 

 was a world observed, since known as Nova Persei, which suddenly 

 became incandescent. How this took place we do not know. Sir 

 Robert Ball suggested that it may have come into contact with some 

 other planet or with some large meteorite, and that the impact 

 produced ignition. 



Professor Loble Y. — The subject of this paper to-day is an 

 illustration of the very great activity of scientific men on the other 

 side of the Atlantic, and especially is this the case in the subject of 

 astronomy. During the last two or three decades the American 

 astronomers have achieved very great results. It seems to me that 

 this in a great measure is due to the support given by the rich men 

 of America, and it is an example to the rich men of this country, if 

 we wish our country to maintain its place in the van of science. 



There are very many points in this paper ; it bristles with points 

 suggestive of remarks. It cannot be adequately discussed in a short 

 time, but may I venture one or two remarks about one or two 

 points 1 



I would like to refer to what has been said with regard to the 

 theory of the rings on the moon being caused by impact. It seems 

 a difficult thing to imagine that these were induced by a moonlet. 

 Where has the moonlet got to 1 The moonlet did not sink into the 

 moon and there is no evidence of its presence. If it had sunk into 

 the moon it would have left a hollow. Professor Hull has very well 

 referred to the remarkable region of Central France in which you 

 have a number of extinct volcanoes. There is another region in 

 Europe which even more resembles the moon's surface, and that 

 is the Phlegrsean fields near Naples, where you have a number of 



