2 THIRD REPORT — 1833. 



attended to, and there are several communications relating to 

 it : among the authors are Dr. Boase, Mr. Carne, Dr. Davey, 

 Mr. K. W. Fox, and Mr. John Hawkins. One of the papers 

 by Mr. Carne is that to which I have before alluded. 



One of the most recent works by foreign writers is that of 

 the late M. Schmidt of Siegen. He was an experienced prac- 

 tical miner, and wrote chiefly with a view to his art, describing 

 the various derangements in mineral veins, and tracing the best 

 rules to be observed in pursuing researches in difiicult circum- 

 stances. He adopts the Wernerian theory of formations, and 

 refers to the author of it as the great master of the subject. 



Though no general theory has of late been produced in re- 

 gular form, yet with the great attention that has been given to 

 geology by so many eminent men, an extended field of observa- 

 tion has taken place, leading to a very general change of opi- 

 nion on most important points ; many conjectures respecting the 

 formation of veins have sprung up, and which, when the facts 

 are more investigated, and they shall have been recorded and 

 classified, may form the groundwork for a more enlarged and 

 rational theory, by which their phaenomena and structure may 

 be explained, and the causes of their formation, the manner of 

 filling up, and the circumstances of the varied derangements 

 and dislocations, may be traced and be better understood. 



The subject is of threefold importance : first, as it relates to 

 science, wherein a better knowledge of veins generally must 

 very materially contribute to sound investigations as to the 

 structure of the rocks that inclose them: secondly, as it is much 

 owing to the pursuit of the minerals which are deposited in veins 

 that we have acquired and may yet extend our knowledge of 

 geology in general : thirdly, in relation to the question some- 

 times proposed as to the usefulness of geological science, the 

 most ready answer may be given, if it be considered that this 

 inquiry will relate to subjects of practical utility, in which man- 

 kind are universally and largely interested. 



Before I proceed to any account of the opinions as to the 

 formation of veins, I would offer some definition descriptive of 

 their character and structure, that in proceeding with our sub- 

 ject we may clearly understand what is meant to be treated on. 



Werner lays it down, " That veins are particular mineral re- 

 positories, of a flat or tabular shape, which in general traverse 

 the strata of mountains, and are filled with mineral matter dif- 

 fering more or less from the nature of the rocks in which they 

 occur. 



. " Veins cross the strata, and have a direction different from 

 theirs. Other mineral repositories, such as particular strata or 



