[- “S73 "} 
LXV. On the Appearances and Relative Positions of the 
Rocks and Veins which form the Opposite Walls of Cross- 
Veins. By W. J. Henwoop, C.L. F.RS. F.GS., 
M. Inst. C.E., Member of the Geological Society of France, 
of the Royal Geological Society of Cornwall, &c.* 
[Illustrated by Plate IV.] 
[t is frequently asserted as a fact not admitting of dispute, 
that when one vein traverses another, the severing is newer 
than the severed vein ; and, consequently, that the portions 
of the latter lying on opposite sides of the former were once 
united: but, if this be true, it necessarily follows that a per- 
fect and exact coincidence will be found between the dimen- 
sions and configuration of these parts; and also that the 
portions of different veins divided by the same cross-vein will 
be found to preserve, on both sides of it, the same relative di- 
stances from each other, either at the same level when the 
fracture has produced a simple separation, or at different ones 
when one or both of the severed portions have undergone any 
motion, either at the time of fracture, or subsequently. 
No part of our inquiry is more important than this, For 
if this coincidence can be established, we have only to ascer- 
tain the relative positions of the severed portions of any vein 
divided by another, and we have a guide to the respective 
situations of all other veins intersected by the same cross- 
vein :—at least of all within moderate limits. 
The heave of one lode by a cross-vein being known, we 
have in this coincidence a sure and infallible guide,—an un- 
avoidable, necessary, and unerring law, which will at once 
indicate in what directions and at what distances all other 
lodes heaved by the same cross-vein may be re-discovered. 
I need not enlarge on the value and importance of such a 
discovery ; for by it the doubts and perplexities with which 
practical miners have been for ages beset, will be at once re- 
moved, and the fruitless cost so often incurred in trying to 
solve the question of their mutual dependence will for ever be 
avoided ; since the re-discovery of a lode heaved by a cross- 
vein, instead of requiring experience and observation, will 
henceforward be merely a matter of simple computation, 
But it is not by the examination of any single heave, or of 
any number of heaves taken each singly, that the truth or 
falsehood of this position can be established, or that we can 
make manifest the resemblance or dissimilarity of the divided 
portions of the same lode, or of the relative distances of dif- 
ferent lodes on opposite sides of the same cross-vein. For if 
* From the Transactions of the Royal Geological Society of Cornwall, 
vol. v. 
