BOOK III. 



53 



A WIDE vena profunda. B NARROW vena profunda. 



Venae dilatatae, in truth, differ also in thickness, for some are one fathom 

 thick, others two, or even more ; some are a cubit thick, some a foot, some 

 only half a foot ; and all these are usually called thick veins. Some on the 

 other hand, are but a palm thick, some three digits, some two, some one ; 

 these are called thin veins. 



Rossler, Becher, Stahl, Henckel, and Zimmerman, all fail to grasp the double essentials. 

 Other writers of this period often enough merely quote Agricola, some not even acknowledging 

 the source, as, for instance, Pryce (Mineralogia Cornubiensis, London, 1778) and Williams 

 (Natural History of the Mineral Kingdom, London, 1789). After Von Oppel, the two 

 fundamental principles mentioned were generally accepted, but then arose the complicated 

 and acrimonious discussion of the origin of solutions, and nothing in Agricola's view was so 

 absurd as Werner's contention (Neue Theorie von der Entstehung der Giinge, Freiberg, 1791) 

 of the universal chemical deluge which penetrated fissures open at the surface. While it is 

 not the purpose of these notes to pursue the history of these subjects subsequent to the 

 author's time, it is due to him and to the current beliefs as to the history of the theory of ore 

 deposits, to call the attention of students to the perverse representation of Agricola's views 

 by Werner (op. cit.) upon which most writers have apparently relied. Why this author 

 should be (as, for instance, by Posepny, Amer. Inst. Mining Engineers, 1901) so generally con- 

 sidered the father of our modern theory, can only be explained by a general lack of knowledge of 

 the work of previous writers on ore deposition. Not one of the propositions original with 

 Werner still holds good, while his rejection of the origin of solutions within the earth itself 

 halted the march of advance in thought on these subjects for half a century. It is our 

 hope to discuss exhaustively at some future time the development of the history of this, 

 one of the most far-reaching of geologic hypotheses. 



