ORIGIN AND DEVELOPMENT OF OBE-DEPOSITS. 143 



The passage of the lode from the kiUas to the granite 

 occurred between the 80 and 120 fathom levels, and tlie lode 

 became more horizontal and thinner. Its dip lessened successively 

 to 68°, 57°, and 50°, and its size was reduced to 24 inches; and 

 finally, in the hard granite between the 170 and 190 fathom 

 levels to 12 inches.* This poor zone discouraged the owners, 

 and, together with the low price of copper occasioned by the 

 great discovery of copper ores at Parys Mountain in Anglesea, 

 led to the abandonment of the deepest workings, and finally of 

 the mine itself, which up to that time had yielded copper ores to 

 the value of 2 millions, a large part of which was profit. At 

 length, through the energy of Capt. Chas. Thomas, the father 

 of the present manager, the mine was re-opened about the year 

 1846, a sum of £3,084 being locally subscribed for that purpose. 

 The pumps which had been drawn up from the 210 to the 160 

 were dropped again, and the mine was drained to the bottom 

 by the end of 1849. Sinking was resumed,! the junction of 

 Harriett's lode with the main lode at the 180 was exjolored, 

 dividends were resumed in 1853, the south lode fell in at the 

 364, and that which had been one of the richest copper mines 

 became the most productive tin mine in Cornwall, so beginning 

 a new era for tin mining in the West of England. 



From the 190 downwards the size of the lode increased, and 

 at 220 it was at least 10 feet thick. In 1858 the tin began to 

 "make" in the granite, the lode being from 20 to 26 feet wide. 

 In January, 1873 they began to drive the 314 fathom level; in 

 1874 the lode had " a very fine appearance ;" in 1882 a depth 

 of 376 was reached, and the present depth of the sump (March, 

 1892) is 422 fathoms. 



The total length of shafts and levels on the lode had in 

 1882 reached 138 miles, of which one half were in Dolcoath 

 alone. At the present time the total cannot be less than 160 

 miles. 



* The corresponding poor zone in Carn Brea Mine extended downwards to 

 the 238 fathom level. 



f From 1800 to 1849 only 55 fathoms had been sunk, or but little over one 

 fathom a year. From 1849 to 1892 over 200 futhoms have been sunk, or about 

 5 fathoms per year. 



