XXIV] SIR CHARLES LYELL 



427 



in my letters on quite different subjects, some of which I 

 wrote upon at a much later period. On February 25, 

 in a letter about the Bethnal Green Museum, I added, 

 " Have you seen the curious paper in the Atlantic Monthly of 

 February on * The Birth of the Solar System ' ? It contains 

 a new nebular hypothesis, quite distinct from the old one. 

 The writer maintains that all we know about the formation 

 of the planets is that they are slowly increasing in bulk from 

 the falling in of meteoritic bodies. He maintains, therefore, 

 that this is the origin of all planets and suns, space being full 

 of cold meteoric dust, heat being produced by its agglomera- 

 tion. Thus all small bodies in space are cold, all large ones 

 hot ; the earth is therefore getting hotter instead of colder, 

 and early geological action was less violent than it is now. 

 Is not that turning the tables on the convulsionists ? 



" Many of the author's statements are, I think, inaccurate, 

 but the view of the formation of the solar system by the 

 agglomeration of cold dust instead of hot vapour seems to 

 have some show of probability." 



This hypothesis was new to me, and I had quite forgotten 

 all about it when I met with it in Sir Norman Lockyer's 

 works while writing my " Wonderful Century," and definitely 

 adopted it as more accordant with facts and more intelligible 

 than Laplace's theory of the intensely heated solar nebula. 



On April 28, after referring to Darwin's regret at the 

 concluding passages of my Qtiarterly Review article on 

 " Man," which he " would have thought written by some one 

 else," I add the following summary of my position, perhaps 

 more simply and forcibly stated than in any of my published 

 works : — 



" It seems to me that if we once admit the necessity of 

 any action beyond * natural selection ' in developing man, 

 we have no reason whatever for confining that agency to his 

 brain. On the mere doctrine of chances it seems to me in 

 the highest degree improbable that so many points of 

 structure, all tending to favour his mental development, 

 should concur in man alone of all animals. If the erect 

 posture, the freedom of the anterior limbs from purposes of 



