NATURAL SCIENCE: 



A Monthly Review of Scientific Progress. 



No. 10. Vol. I DECEMBER. 1892. 



NOTES AND COMMENTS. 



The Interior of the Earth. 



A MORE or less interesting article, by the Rev. O. Fisher, entitled 

 " The Hypothesis of a Liquid Condition of the Earth's Interior, 

 considered in connection with Professor Darwin's Theory of the 

 Genesis of the Moon," appears in the last number of the Proceedings of 

 the Cambridge Philosophical Society (vol. vii., pt. 6, 1892). We say more 

 or less interesting", because mathematical formulae occupy a considerable 

 portion of the paper, and these do not, as a rule, in themselves, 

 interest students of Natural Science. Indeed, a serious regard for the 

 published results of the application of rigid mathematics to the study 

 of the earth, does not seem hitherto to have penetrated deeper than 

 the superficial strata of the magazine article and the student's text-book. 

 The dry flour of the mathematical mill makes excellent paste for 

 holding together the disjecta membra of a popular lecture ; but it never 

 seems to have commended itself as. digestible pabulum to the taste 

 of the everyday geologist, who has his day's work to do, and 

 needs something substantial and nourishing to do it upon. 



In his " Physics of the Earth's Crust" (edition 2), Mr. Fisher 

 claims to have proved that if the crust is as thin as some geologists 

 suppose, and if the age of the world is anything approaching to what 

 geological phenomena appear to indicate, then there must exist 

 convection currents in the interior, which prevent the crust from 

 growing thicker, by melting off the bottom of that crust nearly as fast as 

 it solidifies. He made no suggestion in that work to account for such 

 currents being maintained. At present, however, he thinks that the 

 observations of Professor G. H. Darwin on bodily tides may furnish an 

 explanation ; for a certain amount of heat is generated in the interior 

 of the earth — greater, in proportion, as we approach its centre — by 



