446 Mr. Henwood on the Rocks and Veins 
and the dip remaining the same, this third vein will be simply 
intersected. 
Now, as ¢ dips in the same direction as c, although not at the 
same angle, whilst a has an opposite inclination, it is evident 
that as the movement is parallel to /', that vein will suffer no 
heave; and that as the dip of c forms a smaller angle with /' 
than (5) the inclination of a does, the heaye of c will be of 
smaller extent than that of a. 
The line of motion (s 7) being oblique, and flatter than d, d’, 
will in this instance occasion the heave of c to be towards the 
right-hand as well as that of a, instead of their being in oppo- 
site directions, as would be the effect of a vertical motion. 
This agrees with the facts much better than the hypothesis 
of a vertical movement: but we can arrive at no positive 
proof of the sufficiency or insufficiency of its application to a 
full explanation of the observed phanomena of heaves, unless 
by comparing the actual motions which would be imparted to 
a' andc!, in examples where it is supposed to have been par- 
allel to the dip of the unheaved vein. 
If the same cross-vein traverse several veins, and simply in- 
tersects one of them whilst it heaves all the others, and if these 
displacements have been occasioned by an elevation of one 
side of the cross-vein, or a subsidence of the other, it is evi- 
dent that the direction of the movement must have been par- 
allel to the dip of the vein which is not heaved; and what 
may have been the extent of the motion is determined by the 
distance of movement, in the before-named direction, requisite 
to produce heaves of the extent observed. In other words, 
the direction of the motion is from sto7, fig. 11: and, in 
order to obtain the heaves a, 5! and ¢, d', fig. 11, or a, a' and 
c, cl, fig. 12, its extent must also be the distance s7. Thus 
the unheaved vein indicates the direction, and the heaved one 
the extent of the motion. 
We will now compare the observed phenomena with this 
test, in order to see whether a movement parallel in direc- 
tion to the dip (f, f') of the vein simply intersected, and of 
the distance s7, whilst it produces the observed heave a, a’, 
fig. 12, will, by a motion similar both in direction and extent, 
occasion at ¢,c! a heave which shall correspond with obser- 
vation in every particular; or, on the other hand, whether a 
motion, in the same direction, and in distance sufficient for 
the production of the heave c, c!, will at the same time heave 
a, a in such a direction, and to such a distance, as the actual 
fact presents. 
(A.) At the Consolidated Mines (Table LXII.), Tiddy’s 
or Paul’s cross-course intersects without heaving an elvan- 
