PHILOSOPHICAL SOCIETY OF WASHINGTON. 71 



cal consideration with which he was acquainted seemed to him 

 to conspire in confirming this supposition with a cumulative ag- 

 gregate of force. 



The single fact of stratigraphical folds and faults on so grand 

 a scale as here displayed, looked almost like a crucial test of the 

 hypothesis. That faults continuous for one or two hundred miles, 

 with a throw araouuting in some places to several thousand feet, 

 could take place in a solid ma.^s, or even in a terrestrial crust 

 indefinitely deeper than such amount of slip, seemed contrary to 

 all known principles of physics. As this is a subject of great 

 interest and of some "perplexity," Mr. Taylor said that he would 

 take the liberty of here personally appealing to Mr. Button, as a 

 very able supporter of the Hopkins theory, to help one of the 

 two out of this dilemma. 



Mr. C. E. DuTTON replied that there were subjects on which 

 he felt constrained to maintain a perfectly uncommitting silence; 

 subjects of such intrinsic difficulty that he could only reserve a 

 suspended judgment or conception; and he frankly admitted that 

 this matter of "faults" was one of them. He did not, however, 

 thence feel required to adopt an hypothesis which to him presented 

 many grave objections, and which seemed in many other respects 

 so inadequate. The phenomena of volcanoes, for example, were, 

 he believed, generally held to be quite insufficiently explained by 

 a thin shell ; while the chemical or hydrothermal theory was much 

 more satisfactory. This was explained by Mr. Button at some 

 length. 



Mr. 0. A. ScHOTT remarked, that, inasmuch as the precession 

 of the equinoxes was an unquestionable fact, and as Hopkins 

 and Thomson had shown that this was physically incompatible 

 with a fluid mass of rotation circumscribed by a yielding shell, a 

 solidified mass of considerable equatorial rigidity seemed to be 

 necessarily required, and therefore established. 



Mr. Taylor in reply said, that, first, with regard to the subject 

 of volcanoes, he thought that if the assumption of a thin crust 

 did not sufficiently account for all the phenomena, it was at least 

 not incompatible with them. Taking, for example, the difficulty 

 often urged of the great inequality of hydrostatic column and 



