Remarkable Deposit of Tin- Ore. 71 



course have opposite inclinations, they respectively heave the Wheal 

 Laity lodes in the same direction. 



At a depth of 110 fathoms, where the Wheal Laity north lode is 

 for some distance unproductive, whilst the Wheal Laity south lode 

 is rich in tin ore on both sides of the Cross-course, and for some 

 fathoms both above and below the gallery (level), the Cross-course 

 consists of a rich vein of tin-ore for the whole interval (five fathoms) 

 between the eastern portions of the two lodes, as well as of a fine 

 mass of the same ore at its contact* with the western part of the 

 Wheal Laity south lode. 



(3) At 130 fathoms deep the Wheal Laity south lode is also 

 heaved, but in an opposite direction, by a vein of granitic clay (the 

 Flucan). This fiucan is not prolonged to either of the other Wheal 

 Laity veins ; nor, indeed, does it reach any other gallery (level) even 

 on the same lode. 



(4) The Wheal Comfort lode and the Cross- course have the same 

 direction, but, as already observed, opposite inclinations ; and are so 

 situated that they come into contact on the line of their dips at 

 about 130 fathoms deep. From the point where they first touch 

 each other they descend perpendicularly side by side for about three 

 fathoms, each keeping the same relative position it had previously 

 when separate (viz., the Cross-course on the west, and the Wheal 

 Comfort lode on the east). At length, however, the lode cuts 

 through the Cross-course. After this intersection, though they 

 have changed sides, and their relative position is reversed, they still 

 proceed together, but now take the line of the lode's previous under- 

 lie for several fathoms. "When they separate the lode preserves its 

 dip ; but the Cross-course, though it resumes the previous direction 

 of its inclination, dips eastward far more rapidly than before. It 

 may, indeed, be generally observed, that a vein which has been dis- 

 placed by another, whether the intersection be horizontal or vertical, 

 makes (if I may be permitted the expression) an effort to resume its 

 original course. 



(5) The Wheal Laity lodes are intersected as well by the Wheal 

 Comfort lode and the Cross-course, during their union, as by each 

 of them when separate ; the union, however, has little or no influence 

 on the extent of the heave. 



Many details of local, and some, indeed, of general interest, 

 scarcely need be mentioned here, as this paper may be deemed sup- 

 plementary to my remarks on the Saint Ives District ;* and espe- 

 cially to a description of a similar interesting formation at the St 

 Tves Consolidated Mines, which has already appeared in the Trans- 

 actions of the Royal Geological Society of Cornwall.! 



A small stream issues from the Wheal Laity north lode at 150 

 fathoms deep, having a temperature of 71° ; whilst that of the water 



* Vol. v., p. 16. t Idem, p. 21. 



