GEOLOGICAL SOCIETY. 163 



missing by some other chance, will give a fallacious re- 

 sult. The business of mining does not repose on cer- 

 tainty, but on probability, and all that we can do in such 

 investigations is only to search for the greatest proba- 

 bility. 



Fig. I. 



Map or Ground Plan of an Estate called " The Rap- 

 pahannock or Smith's Gold Mine" in Stafford 

 County, Virginia. 



Road into the mine from turnpike. 



Rappahannock River. 



