XXX1V 
left-hand—the greater or smaller-angle,—and the extent of dis- 
placement under different angles of incidence, are —* ‘ 
Lopes, (heaved) displaced towards the 
LopEs Extent of 
incidence, |,,2mPy { ye 
* | intersected. Right-hand. | Left-hand. Wee at se ment. 
0°—10° = = = — = -—- 
10°—20° x x = x oa 6:0 feet. 
2:0°—30° 0:01 0:03 x 0:03 x eons 
30°—40° 0-01 0:92 0:02 0:02 0:01 24:2 ,, 
40°—50° es 0:04 0-03 0-05 0-02 |32-4 ,, 
50Q0—60o 0:03 0:03 0:03 0:05 x LO Ae 
60°—70° 0:05 0:06 0:05 0-11 0:01 24 
70°—80°. 0:04 0:14 0:07 0:15 0:06 WE) 4 
80°—90° 0:09 0:18 0:07 0:22 0:04 14 Sie 
Proceeding from general results to particulars.—One instance, 
at least, is on record of a lode and a cross-vein each alternately in- 
tersecting the other twice, at different depths in the same mine.+ 
The general rule is that the displacement of the same lode by the 
same cross-vein is in the same direction (towards the same hand,t 
though to unequal distances at different depths ;§ yet cases are 
not unknown of the same Jodes being heaved towards the right-hand 
at one, but to the left at another, spot;{ indeed the contour of the 
parts of (heaved) displaced lodes in contact with opposite (walls) 
sides of (heaving) displacing cross-vems have often but a slight— 
and sometimes scarcely any resemblance.|| Most of the dodes tra- 
versed by the same cross-ven are either simply intersected or 
heaved the same way ; nevertheless one, here and there, is some- 
times displaced in the opposite direction; such exceptional cases, 
however, amount to only 0-037 of the whole number observed.% 
The same Jodes are frequently intersected by several, nearly 
parallel, cross-veins ; but—though only a few fathoms apart—they 
sometimes suffer different (heaves) displacements.** 
The elvans traverse the same districts as the Jodes, and—owing 
to slight differences in direction and dip—are frequently inter- 
* Pryce, Mineral: Cornub: p. 99. Hawkins, Cornwall Geol: Trans: 
li., p. 228. Henwood, Jbid, v., p. 301. 
+ Henwood, Cornwall Geol: Trans: v., p. 326. 
+ Ibid, v., pp. 313-314. 
§ Ibid, v., pp. 308-309; vii., p. 182; viii., p. 717. 
|| Ibid, v., pp. 877-379, Pl. xii., Fig. 15-20. 
q Ibid, v., pp. 320-324; vil., pp. 182-183; viii., pp. 683-684. 
** Ibid, V., pp. 316-320; vii., p. 183; viii., pp. 683-684, 717. 
