404 
MR. R. W. FOX ON THE ELECTRO-MAGNETIC PROPERTIES 
able depth, including between them vast portions of rock perfectly insulated 
by the ore or vein-stones from the general mass : these, it is evident, could not 
have existed as fissures for a moment. 
3rd. Veins are continually subject to changes in their horizontal direction 
and underlie ; their size also often varies exceedingly, one part being many 
times wider than another, without any reference to their relative position or 
depth under the surface. 
4th. Although a portion of their vein-stones are usually quite distinct in their 
characters from the rocks they traverse, they are generally, in part, of the 
same nature, and vary with the containing rocks, whether granite, elvan, killas, 
&c. ; and they are commonly too regularly arranged in the veins, and are 
found inclosing insulated portions of the ore, &c. in their very substance, to 
admit of the idea of their having been originally mere broken fragments of the 
inclosing rocks. 
At Dolcoath Mine there is an instance of one ore vein intersecting another 
at different depths, and being itself intersected and even shifted by the same 
vein at a greater depth. I have given a sketch of these intersections in Fig. 27, 
(for which I am indebted to Captain Petherick of that mine,) as I am not aware 
that it, has been before noticed. 
Many other facts might, if it were necessary, be accumulated, relative to the 
position and intersections of veins, as well as the nature and arrangement of 
their contents, which, with those I have stated, are calculated to throw entire 
discredit on the various hypotheses which have been invented to account for 
their origin. But my object is, rather to suggest whether the arrangement of 
veins, &c. does not argue design, and a probable connection with other pheno- 
mena of our globe. 
Metalliferous veins, and those of quartz, &c. appear to be channels for the 
circulation of the subterraneous water and vapour; and the innumerable clay 
veins or “ ffucan courses” (as they are termed in Cornwall,) which intersect 
them, and are often found contained in them, being generally impervious to 
water, prevent their draining the surface of the higher grounds as they other- 
wise would, and also facilitate the working of mines to a much greater depth 
than would be practicable without them. 
With respect to their electrical properties, it may be observed, that ores 
