448 Mr. Henwood on the Rocks and Veins 
discrepancy between the computed and observed results is 
surely inconsistent with accidental fluctuation (e). 
(C.) At Wheal Unity Wood the Great elvan-course dips 
N. 40°—50°: Trefusis lode also dips N. 66°—82°; the Little 
Ore lode likewise dips N. 52°—60°; and Pits-an-vollar lode 
inclines in the same direction 60°—70°. The flucan simply 
intersects the elvan-course; whilst it heaves Trefusis lode 36 
feet at 26 fathoms deep, and 30 feet at 36 fathoms; the 
Little Ore lode 12 feet at 60 fathoms deep, and Pits-an-vollar 
lode 21 feet at the same level. In all these cases the heaves 
are toward the left-hand. 
The elevatory action, if any, must of course have been 
parallel to the dip of the simply-intersected vein,—the elvan. 
Now in order that a motion in this direction should produce 
a heave of 36 feet in Trefusis lode at 26 fathoms deep, the 
extent of the movement must be from 85 to 90 feet; whilst to 
produce a heave of 30 feet, in the same lode, at 36 fathoms, 
a motion of only about 55 in the same direction would be re- 
quisite. But an elevation of 90 feet, in a direction parallel to 
the underlie of the elvan, would produce a heave of 21 feet 
in the Little Ore lode at 60 fathoms deep, and one of 55 feet 
would eccasion a heave of 12 feet; whereas the same quantities 
of motion, acting in the like direction on Pits-an-vollar lode at 
60 fathoms, would respectively cause heaves of 4.5 and 27 feet. 
Thus, in order to the production of the observed phzeno- 
mena, we have at Trefusis lode these scarcely compatible con- 
ditions :—either the direction of the motion was the same at 
both, and its extent different, or the extent of motion was the 
same at both, and its direction different. 
The same extent and direction of motion which will pro- 
duce the heave observed in ‘Trefusis lode at 36 fathoms deep, 
will also give the real heave of the Little Ore lode at 60 fa- 
thoms; whilst the extent of motion necessary to obtain the 
heave of the former at 26 fathoms deep, will occasion a heave 
of 21 feet in the latter; being an excess of 9 feet over the ob- 
served distance. 
If the motion at Pits-an-vollar lode at 60 fathoms deep were 
of similar direction anc extent to that assumed to have acted 
on Trefusis lode at 26 fathoms deep, the heave would have 
been 45 feet; or, if the same as that at 36 fathoms, it would 
have been 27 feet. Now the observed heave is 21 feet; and 
in order to obtain this with a motion parallel to the unheaved 
vein (the elvan), an elevation of about 40 feet would have suf- 
ficed : and such a degree of motion, at the same depth, would 
have occasioned a heave of about 9 or 10 feet in the Little 
Ore lode, instead of the observed distance of 12 feet (/). 
