which form the opposite Walls of Cross-veins. 445 
short, one lode would be heaved towards the right-hand, as a, 
a', and the other to the left, as c, c!. These results are not 
mere probabilities, but physical necessities, which, and which 
alone, must inevitably follow a vertical elevation of portions 
of lodes having opposite dips. 
In this case, too, there can never be a simple intersection 
unless the dip is reversed: and not even then, unless the ele- 
vation be to such an extent as will directly oppose to each 
other portions which have these opposite inclinations. 
The examples, therefore, in which lodes with opposite 
inclinations are heaved in the same directions (a, 0, ¢, d, 
e, f; g, &c.), as well as those in which there are heaves at 
some levels, and simple intersections, without reversed dips at 
others (4, 7, q), are equally unaccounted for on this hypo- 
thesis. The insufficiency of its general application is also 
most decided in all cases where the cross-vein heaves the 
Jodes, but simply intersects the elvan-courses which lie be- 
tween them (e, f, g,7,p, &c.). These contradictions between 
fact and theory nothing can reconcile. 
(3.) Let us now take an example, in which, as in the last, 
‘there are two veins having opposite inclinations, with a third 
vein between them which dips in the same direction as one of 
the others, but at a different angle. Let the assumed motion 
be parallel to the dip of the latter. 
I put this as a case which, in some respects at least, satisfies 
the conditions left unsolved by the last, viz. two lodes, having 
opposite dips, being heaved in the same direction, whilst a 
third (an elvan-course) occurring between them is simply in- 
tersected. 
Let A B (Pl. IV. fig. 11, 12), as in the last case (2.), be 
the unmoved surface, and A! B! the elevated one; Y Z the 
unmoved transverse section, and Y! Z! that which has been 
raised; a, a', and c,c! the superficial parts of the same lodes, 
which, when at the same level, had been respectively united ; 
and ¢, e' the upper portions of the elvan-course, once united, 
and still unheaved: 4, b', d, d', and ff! the deeper parts of 
the three veins respectively. 
Now if A! B' be further from us than A B, and if we sup- 
pose it to be elevated on the line s 7, parallel to the dip of f,/', 
and the superficial portion above A B removed as before de- 
scribed, the plan, fig. 12, will present an idea of the new state 
of things; the cross-vein, w 2, having been formed during the 
elevatory action. 
w x will break the continuity of a, a', and c,c', and heave 
both of them; whilst as the motion upward, on the line s7, 
parallel to /', will keep e and e! still in contact at all levels, 
