. Mathematical and Physical Papers. 207 



thought that in future ages gold veins may be worked where the 

 gold at this present time is not deposited. 



In this paper the inquiry has been limited to gold, but it is 

 easily seen that similar conclusions could be reached respecting 

 other metals, and that water has had an important part in determin- 

 ing the location and condition of ore deposits. We can find near 

 the surface of the earth all the material needed to supply the min- 

 eral veins, and it is unnecessary to suppose that the heavy metals 

 must have come from great depths. 



