380 Mr. Henwood on the Rocks and Veins 
oblique motion has ever taken place) form 227 per cent. of the 
total number of intersections. 
Again, the heave of a lode by a cross-vein may be occasioned 
either by a horizontal, vertical, diagonal or curvilinear motion of 
the portion on either side, or on both sides of the cross-vein. 
(1.) A simple horizontal motion will occasion an equal dis- 
placement at all depths, which almost every fact we have con- 
sidered (6, 7,7, £, 1, &c.) shows to be rarely, if ever, the case. 
In all other kinds or directions of motion, the extent or di- 
stance of the heave (displacement) depends on the angle in- 
cluded between the line of dip of the lode and that of the 
direction of the motion, and also on the extent of the motion. 
(2.) Let the superficies A B, A! B', A? B? (PI. IV. figs. 1, 2), 
respectively, be the surface or ground-plan supposed to have 
formerly been at one level; Y Z, Y! Z!, Y? Z? the vertical 
planes exposed by the respective subsidences of A! B! and 
A? B*:—a, a!, a? the superficial portions of the same vein 
which were originally united at the same level; and 4, b', 6? 
the profiles or transverse sections which show the inclinations 
or downward courses of the respective parts. 
Now, supposing the original state restored, and AB, A' B', 
A’ B? to be on the same level; let us imagine a fracture to 
take place in the direction w 2, and at the same time the por- 
tions A! B! and A? B? (which are still united) to subside on 
the line or in the direction o p. It is obvious that the por- 
tion or end of the lode a! in the subsided portion A! B!, A* B° 
(by subsiding in the direction 0 p instead of o g, which is the 
dip of the lode) will not be found at p in contact with o b q, 
the portion of lode contained in the mass of rock A B, Y Z. 
Therefore the lode has suffered a heave towards the right- 
hand, the extent of which is the distance p g; and as the lode 
is straight, this extent is the same at all levels. 
We will now suppose a second fissure to be formed on the 
line y z, and the portions of rock A Band A! B', with the 
lode they contain, to be stationary, and the mass A? B? to 
subside still further, but that the line of subsidence is now 
parallel to the dip of the lode 4',in the direction of r s, instead 
of being oblique to it, as in the last instance. As the dip of the 
lode is perfectly uniform, the superficial portion a? will con- 
tinue in contact with 5! at s, and consequently there will be 
no heave at that point. 
It needs but little consideration to discover that the very 
same results must be necessarily obtained whether AB be the 
fixed mass, and A! B', A? B? subside; or whether A® B? be the 
stationary portion, and A' B', A Bare elevated: provided only 
that the lines of motion be still 7 s and o p respectively. 
