part 1] AisnsrivERSAET address or the president. Ixxix 



It has a perfect!}' definite and precise meaning, as the inclination 

 of a sloping surface, measured from the vertical ; apart from an 

 obsolete use in agriculture, the Avord is restricted to mining or 

 geology, and, consequently, it is free from any risk of being mis- 

 understood, for it either carries with it a definite and precise 

 intention, or is absolutely meaningless to the reader or hearer. 

 As an example of the other class we may take the word 

 ' normal ' ; not only has this word a general dictionary meaning, 

 and connotation in ordinary intercourse, but it is also used as 

 a technical term in several branches of natural knowledge, and 

 in each the meaning is distinct and different, from that which 

 it bears in other sciences and from that which the uninitiated m 

 any science would attach to it. Hence, when using this word, 

 we must be quite clear as to the precise meaning in which it is 

 used, and avoid the fallacy, only too common, of making it first 

 express a definite fact and then extending its meaning by the 

 connotation whi_di it would have in a different context; it gives 

 an extreme instance of the danger involved in taking a word out 

 of the general vocabulary of our language, and giving it a special 

 technical significance, yet I Avould not, on that account, advocate 

 its abandonment. It would be impossible to devise another term 

 wholly free from the same danger, unless some entirely meaningless, 

 and probably cacophonous, word were invented ; for, so long as the 

 name is derived in any way from existing words and roots, it must 

 from the outset carry with it a more extended meaning than the 

 special one intended to be implied. 



A more weight}^ consideration, perhaps, is the desirability, in 

 certain stages of knowledge, of making use of words which have 

 not a rigid limitation of meaning, but rather of such as have ill- 

 defined limits, capable of extension and modification as the advance 

 of knowledge makes necessary or advisable. The old distinction 

 of normal and reversed faults was made in the early days of our 

 science ; in the light of what we now know it is certainlv in- 

 adequate, but, until our understanding of the processes, causes, and 

 mechanism of the production of faults has advanced much beyond 

 its present state, no approach to a final or complete classification is 

 possible. For these reasons the old terminolog}^ may be retained, 

 provided that we distinguish between the technical and untechnical 

 meanings of the words, and remember that, though normal faulting 

 in the former sense may also be normal in the latter in certain 

 regions, it is most definitely not so for others, and not necessarily 



