THE 



EDINBURGH NEW 

 PHILOSOPHICAL JOURNAL. 



Remarks cni the Theory of the Elevation of Mountains. By 

 George Bellas Greenough, Esq. F.R.S., &c. &c. &c. 

 President of the Geological Society of London *. 



Among the subjects which have for some years past engaged 

 the thoughts of geologists, none perhaps has excited so general 

 and intense an interest as the Theory of Elevation. I shall 

 avail myself, therefore, of the present occasion to lay before you 

 a connected statement of the scattered facts and opinions upon 

 which it rests. 



On entering upon this subject, it is necessary to understand 

 distinctly what is meant by Elevation. Definitions have recent- 

 ly been decried, I think unwisely. The formation of definitions, 

 it has been said, and the estabhshment of unerring distinctions, 

 are among the last, and not the first steps of systematic know- 

 ledge. Equally true, and far more salutary, is the lesson that 

 science cannot be advanced by equivocation. As in trading con- 

 cerns fixed weights and measures are necessary guards against 

 fraud, so in philosophical investigation words of definite mean- 

 ing are indispensable securities against sophistry and self-delu- 

 sion. Euclid did not end, he began with defining. Mathema- 

 tical certainty has no other basis than mathematical precision, 

 and the greater part of those absurdities which from time to time 

 attach themselves to all other branches of knowledge, derive their 

 subsistence from ambiguity of language and a dearth of defini- 

 tion. 



• These Remarks form part of Mr Greenough's lately published Address, 

 delivered before the Geological Society of London. 



VOL. XVII. NO. XXXIV. — OCTOBER 1834. P 



