266 On the Matter composing the Interior of the Earth. 



4. The labour bestowed on the problem investigated could 

 scarcely be considered at all necessary or fruitful, except as 

 affording an admirable illustration of the results flowing from 

 the employment of hypotheses framed in direct contradiction 

 to the fundamental conditions to which every truly philoso- 

 phical hypothesis must conform. It is scarcely necessary to 

 add, that the conclusions of Mr. Darwin, as well as those of 

 Sir William Thomson, cannot be considered as having invali- 

 dated the carefully framed hypothesis that the earth consists 

 of a solid crust physically similar to the rocks we are enabled 

 to observe, and a contained spheroid of liquid matter partaking 

 of the established properties of liquids, and physically similar 

 to the liquid rock poured out by volcanic openings. 



5. It is with much satisfaction that I can trace a gradual 

 growth of more correct physical views on the questions referred 

 to in this paper. In ' Nature,' vol. v. p. 288, a paper appeared 

 in which I ventured to criticise Sir William Thomson's memoir 

 on the Rigidity of the Earth, in the ' Philosophical Transac- 

 tions.' At the Meeting of the British Association in Glasgow, 

 Sir William Thomson acknowledged the invalidity of many of 

 his arguments, and requested his audience to draw their pens 

 through paragraphs from 23 to 31 in his paper. These para- 

 graphs contain statements and reasonings which I had already 

 shown to be inconclusive in the paper which has just been 

 quoted. 



In Mr. Darwin's paper, recently communicated to the Bri- 

 tish Association, he admits that in discussing the precessional 

 and tidal phenomena of a viscous liquid, the supposition of an 

 elastic spheroid would lead to very different results — that is to 

 say, results very different from those deduced by himself and Sir 

 William Thomson regarding the earth's structure, and which 

 the followers of the late Sir Charles Lyell have frequently 

 assumed to be established. Thus the late Mr. Poulett Scrope 

 appears to have referred to the bearing of the mathematical 

 investigations alluded to, on what he calls " the sensational 

 idea " of an internal incandescent fluid beneath the solid crust 

 of the earth. He forgot that an idea may not be the less true 

 because it is sensational. The idea of antipodes was at one 

 time regarded as highly sensational. Those who witness a 

 great earthquake or a volcanic eruption are usually impressed 

 with the sensational character of the phenomena. 



6. A traveller who was in Portugal more than forty years 

 since, met a woman over one hundred years of age, and asked 

 her if she recollected the great earthquake of Lisbon. She 

 replied, that it was the event of all others in her long life 

 which she ought to vividly recollect, on account of its impres- 



