which form the opposite Walls of Cross-vetns. 377 
depths: Williams’s lode heaves the cross-course 4 feet to- 
wards the left-hand ; the cross-course then intersects Trathan’s 
lode, and at some levels heaves it towards the right-hand; and 
lastly, it heaves the Black lode 11 feet towards the left-hand. 
(r.) At ‘Tincroft the Old lode dips northward, and simply 
intersects the eastern cross-course. The same cross-course 
then heaves Highburrow lode, which dips south, 1 foot-to- 
wards the right-hand ; it next intersects a mass of granite, 
and also an elvan-course which dips northward, but heaves 
neither of them. It then crosses two granite veins, one dip- 
ping north and the other south, and afterwards Martin’s lode, 
which dips north, heaving all three towards the right-hand. 
On meeting Dunkin’s lode, at 26 fathoms deep, the cross- 
course is heaved 4 feet towards the right-hand; whilst at 
84 fathoms the same cross-course heaves the same lode 
4 feet also towards the right-hand; and lastly, the cross- 
course heaves the south lode, which dips northward 2 feet, in 
the same direction. 
Thus the heaves of two lodes by the cross-course lie be- 
tween two intersections of the same cross-course by two 
other lodes; whilst one of the intersections of the cross-course 
by a lode is included between two heaves of lodes by the 
cross-course. (Pl. IV. fig. 6.) 
(s.) In the well-known case at Dolcoath* (Pl. IV. fig. 2), 
Entral north lode heaves Wheal Bryant cross-course 9 feet 
towards the right-hand; the same cross-course heaves two 
veins, one 12 and the other 30 feet, towards the right-hand, 
and the western portion of the jatter is in elvan, whilst the 
eastern is in slate: the cross-course traverses but does not 
heave the elvan-course. 
In the same mine, at 56 and 76 fathoms deep, the Caunter 
lode heaves Harriette’s lode, respectively, 6 feet and 4 feet ; 
but at 96 fathoms Harriette’s lode heaves the Caunter lode 
90 feet, and at 116 fathoms, 120 feet. (Pl. IV. fig. 3.) 
(t.) The Carbona, at Saint Ives Consols, has been already 
described, and also its intersection by the Middle trawn. 
It is necessary, however, to repeat here a few particulars. At 
80 fathoms deep, the Carbona, deviating from its usual direc- 
tion (S.Iz.), takes that of the Middle trawn, and accompanies 
it for 25 fathoms. Within a few fathoms of this junction the 
trawn partakes of, and indeed almost assumes, the mineral 
* This most important series of intersections was first brought under my 
notice by the kindness of Capt. Petherick. It is figured in Dr. Boase’s 
Primary Geology, p. 190, fig. 23; and it has also been described by me, 
Edin. New Phil. Journal, xxii, (1836), p. 163; and Report of the British 
Association (1837), p. 74. 
Phil. Mag. 8. 3. Vol. 22. No. 146. May 1843. 2C 
