which form the opposite Walls of Cross-veins. 449 
In the foregoing examples the elvan-courses are the simply- 
intersected veins: it may now be desirable to examine a few 
in which the unheaved veins are lodes. 
(D.) At Fowey Consols, at 90 fathoms deep, the cross- 
course simply intersects Bone’s and Jeffery’s lodes; but at 
95 fathoms, where Crosspark lode is in two veins, it heaves 
one of them 9, and the other 15 feet towards the right-hand, 
and at 200 fathoms, where there is only one lode, it is heaved 
2 feet in the same direction (q). 
The vein of Crosspark lode, which in dip most closely ap- 
proximates to the unheaved lodes (Bone’s and Jeffery’s), is 
heaved further, whilst the other vein, which differs most from 
them in inclination, is heaved the smaller distance; and yet 
the difference in the inclinations of these veins is only about 
three degrees. Now, taking their mean dip and the direction 
of the movement to be parallel to Bone’s and Jeffery’s lodes, 
the extent of motion requisite to produce a heave of 9 feet 
would be about 26 fathoms; but, to obtain a heave of 15 feet, 
an elevation of nearly 39 fathoms in the same direction would 
be requisite. Applying these directions and extents of move- 
ment to the lode at 200 fathoms deep, where it has a flatter 
inclination, a motion of 26 fathoms would cause a heave of 
30 feet, and one of 39 fathoms a heave of 39 feet: the actual 
heave, however, is only 2 feet. 
Here, then, we have, in one case, that lode heaved furthest 
which, according to the theory, ought to have been heaved 
the least; and in the other a heave of only 2 feet, whereas 
the hypothetical motion demands one of 30 or 39 feet. 
For the present I pass the consideration of the heave of this 
same cross-course by Williams’s lode, as it will be again ne- 
cessary to advert to it (V.—3). 
(E.) At Stray Park the two lodes have opposite dips, and 
both are intersected by the same cross-courses. Now a hori- 
zontal motion (1.) would have caused similar heaves in both 
lodes at all levels. A vertical motion (2.) would have caused 
them to be heaved at all levels, and everywhere in opposite 
directions. Any movement parallel to the dip of one of them 
(3.), would, for the most part, have simply intersected, or at 
any rate but slightly heaved it* ; whilst its effects on the other 
lode would have been much greater. Lastly, a rotatory mo- 
tion (4.) would have produced results constantly increasing 
in magnitude as the spot was more remote from the neutral 
point or centre of motion. 
* In consequence of the lode’s dip not being perfectly uniform. 
Phil. Mag. S. 3. Vol. 22. No.147. June 1843. 2H 
