DESCHtPTION OF THE OPERATIONS AT DOLCOATH MINE. 193 



and raising a larger quantity of tin, as well as making greater 

 profits, than any other tin mine in the world. 



The total length of levels driven on the lodes, together with 

 cross-cuts, is about fifty miles, in addition to twelve miles of shafts 

 and winzes. Our present rate of sinking and driving is about a 

 mile per year. 



The ground generally, especially in the deeper parts of the 

 mine, is very hard, and but little stuff can be broken except by 

 blasting. The average cost of driving an end 8 feet high and 6 

 feet Avide (our usual size) is upwards of £20 per fathom. Where 

 the lode throughout is of similar quality we usually set it to be 

 raised at a certain price jper ton of stuff (veinstone and crude ore), 

 the condition being that the men breaking it are only to be paid 

 for that which will produce at least three-fourths per cent, of tin 

 ore. The total average cost of breaking the stuff and sending it 

 to surface in this manner is about five shillings and sixpence per 

 ton. Where the lode varies much in quality, requiring selection 

 and greater care in working, we usually set it to be worked on 

 tribute. 



The mine has been producing of late about 87 tons of black 

 tin (or tin ore) per month, or 1050 tons per year; in order to 

 obtain which we raise and stamp about 1000 tons per week, or 

 52000 tons per year ; so that the average produce of our tin stuff 

 as raised from underground is as near as can be two per cent, of 

 tin ore — or, in other words, only o^e part in 50 (except a little 

 arsenic) is of any value, the other 49 parts being worthless. 



To work so deep a mine (nearly 2000 feet from surface) and to 

 raise so large a quantity of tin from so hard a rock is necessarily 

 attended with great labour and expense. There are two steam 

 engines, respectively of 85 and 60-inch cylinder, employed in 

 pumping water for draining the mine, and three steam whims 

 drawing stuff (but of these one only works occasionally). There 

 are also two steam engines employed in stamping and one in 

 working the " man engine " for lowering and raising the miners. 



Our man-engine >' consists of a single-rod working 12 feet 



* Loam, Reports of the Royal Cornwall Polytechnic Society, II, p. 35. 

 Phillips, ihid, p. 43 ; IV, p. 57. Jones, iUd, VI, p. 63. Basset, iUd, VIII, 

 p. 59. Gordon, ihid, IX, Part 11, p. 6. Lemon and others, ihid, p. 12. 



