Ch. XVI.] TO THE PREVAILING THEORY. 377 



consonant with the usual forms of fractures; and that the 

 portions of rocks, similar to the adjacent mass, which are 

 included within the quartzoze substance or matrix of these 

 veins, and which are often of great size, and arranged con- 

 formably with the adjacent strata, could not be maintained in 

 such positions, within either empty fissures, or in the midst 

 of igneous injections, but would fall to the sides of the 

 veins, or even to their bottom, far below the present limits 

 of mining operations. 3. The nature of their composition, 

 and the mode of their connection with the adjacent rocks, 

 both by mineral transitions, and a community of con- 

 cretional structure, are facts which do not indicate the 

 introduction of foreign and heterogeneous substances into 

 fissures; and such an origin is rendered still more pro- 

 blematical, by the occurrence of subordinate veins in large 

 lodes, or what has been termed veins within veins ; for how 

 could fissures be formed and filled in such situations, and not 

 only in the matrix, but also continuously through the con- 

 solidated portions of rocks ? and moreover, under such 

 circumstances, how could these lesser veins exhibit all the 

 phenomena of intersecting lodes ? 4. We do not subscribe 

 to the axiom just quoted concerning the relative ages of veins 

 as indicated by intersection ; because every description of 

 veins, whether segregated, contemporaneous, or true, presents 

 precisely the same appearances : this, in the second instance s 

 has been asserted to be fallacious, but we have disputed the 

 correctness of this view of the case at some length. Moreover, 

 the different orders of veins interfere with each other in like 

 manner, by which it seems to be proved that they are all of 

 the same nature. Lastly, the division of true veins into classes 

 of different ages cannot be maintained, for each class affords 

 exceptions ; and not only so, but even the relative age of two 

 veins, as in Dolcoath, may be inferred to be of a certain deno- 

 mination in one part of the mine, and of a very different one 

 in the other ; because, at a given level, A traverses B, and at 

 another, B is the intersecting vein. 5. Although the heaves 



