MIRACLES OF SCIENCE 



matter so rapidly, thanks to their greater gravitation- 

 al power, as to superheat their substance to the stage 

 of liquidity or gaseousness. Such is still the condition 

 of Jupiter and Saturn, and probably also of Uranus 

 and Neptune. But our earth and the other smaller 

 planets were probably from the beginning solid in 

 structure, though doubtless developing a high interior 

 temperature, through impact and compression. Their 

 growth would be decreasingly rapid as the outlying 

 planetesimal matter within their sphere was more 

 nearly exhausted. But their growth continues, in a 

 minor degree, even now; for it is well known that the 

 earth sweeps up something like a hundred million me- 

 teors each day, these meteors being, supposedly, be- 

 lated fragments of the original spiral nebula. Occa- 

 sionally a larger fragment of world-stuff in the form 

 of a giant meteorite falls into our atmosphere, and 

 finds at last a resting place on the earth. 



THE DISCONCERTING CONDUCT OF PHOEBE 



"Give a dog a bad name and you soon hang it," 

 says the old proverb. It seems to be much the same 

 with a theory. Once you challenge it with a discord- 

 ant fact or two, new evidence against it begins to crop 

 up on every side. So it is not strange that just as 

 Professors Chamberlin and Moulton were challenging 

 the theory of Laplace, a very striking piece of evi- 

 dence against the theory should have been brought to 

 light from a quite unexpected quarter. 



The new evidence was secured by another famous 

 American astronomer, Professor W. H. Pickering. 

 While examining a star photograph made at the ob- 



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