EXPLANATION OF THE PLATES, 



PART II. 



PLATE 6. 



Veins of granite and porphyry traversing the schist of Cruachan. 

 Fig. 1, Passage of porphyry veins through schist already traversed by veins of 



granite. 

 Fig. 2. A similar circumstance, representing at the same time the parallel and 



adjoining position of two veins of differently coloured porphyries. 



PLATE? 



Plan and Sections of tlie mine of Huel Peever, shewing the interruptions 

 that have occmred to the veins in that mine. The ground plan, Fig. I. 

 represents the effects produced by the cross courses intersecting the veins 

 that run in tlie direction of east and west. The transverse section, Fig. 2. 

 shows tlie interruptions among themselves of the veins that run in an east 

 and west direction, occasioned by the various degrees of inclination of their 

 underlie. The tin vein is intersected by the copper vein, and they are both 

 again affected in a similar manner by the two slides. 

 T!ie longitudinal section is explained, p. 144. 



PLATE 8. 



Tunnel 4)f the Tavistock Canal. 

 The various beds and lodes met with in working through the bill are here 

 represented, as well as the number of shafts sunk in the process of making 

 the Tunnel. 



PLATE 9. 



Map of Sky, described p. 156. 

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