16 GEOLOGICAL RESEARCHES IN 



large, firm pieces formed of well-defined layers, with conchoidal fracture and bril- 

 liant metallic lustre/ 



Sp. gi- 1.55 



Parts of lead reduced by one part of coal . . . . 33.40 



Units of heat .......... 1682.00 



Percentage of ash (gray) . . . . . . . 4.00 • 



Eight men produce about four tons daily, and the selling price at the mouth of 

 the mine is $1 70 per ton. A short distance N. W. of the Tatsau is a high cliff of 

 porphyry, forming part of the edge of the porphyry hiUs that bound the Chaitang 

 district on the west. This rock is said, by the Tatsau miners, to cut off the coal 

 and its accompanying rocks. 



The annexed wood-cuts (Figs. 2 and 3) serve to give some idea of the Tatsau mine. 



/■^///////7/m 



Fig. 3 



The entrance is by the gallery a, at first horizontal, then rapidly descending to 

 the inclined shaft h. These are in the smaUer and lower seam. A drift leads to 

 the level fZ, Fig. 3, in the larger seam. In working the coal the miners drive a 

 level, as far below the surface as the amount of water will permit, and extending 

 horizontally along the foot wall as far as the limits of the mine, with a breadth 

 equal one-half of the seam when this is less than twenty feet. Beginning at the 

 end 7i, they excavate the coal below the gallery, at /, to a depth of from ten to 

 twenty feet. When this has advanced a short distance they break down from the 



' See Appendix No. 2. 



