100 Remarks on the Transition Rocks of Werner. 
two specimens from the same quarry could be ex 
pected to be. 
10. Elvan, as pointed out at Wheal Friendship. This I 
took for coarse-grained Grauwacke ; it was very dif- 
ficult to break, and a very small proportion of it ex- 
posed to view. I could not, therefore, observe its 
connection with the surrounding rocks; but, from 
more minute examination, I suspect it may belong 
to a bed of Greenstone. 
11. Capel, a veinstone or Salland, composed of Quartz 
' penetrated by Chlorite. 
12. A Buneh of ore is here exhibited by a portion of Cop- 
per pyrites, in a vein of Quartz, which represents 
the lode. When found in this way in a mine, it is 
termed a Bunch of Metal. 
13. A heave to the right, the Killas is here traversed in 
different directions by Quartz veins; that marked 
A represents a lode, intercepted and heaved to the 
right by B, across course. When the lode is cut 
in a very oblique direction, tt is said to be caunted. 
14, A Horse, when a lode is divided, and joins again, it is 
said to take horse, and the included mass in this spe- 
cimen is. called the Horse of Killas, &c. 
15. A Squat, when the lode suddenly enlarges, it is called 
a Squat; and the metal it contains a Squat of Ore. 
-—By means of this vocabulary, I very soon became 
familiar with many of the commonest mining terms 
in the country. 
In order to form a junction between the Tavistock 
Canal and the Tamer, it became necessary to drive 
a tunnel, for a mile and a half, through a hill called 
Morwel Down, which promises to be a source of 
interest to the geologist. In forming this tunnel, 
several powerful veins of clay porphyry have been 
penetrated, the substance of which is in some places 
Nos. much disintegrated, in others firm and compact ; 
16-19. veins supposed to correspond have since been ob- 
served on the surface. 
20. In the tunnel, the Clay Porphyry alternates several 
times with the Killas, which is here of a light-gray 
colour, and a soft friable texture. 
In the course of this undertaking, two workable me- 
tallic veins have been intersected : no traces of either 
had been found on the summit of the hill, although 
diligently examined. 
#1. Passing the Tamer, we enter Cornwall, and at Cents 
ake 
