312 BROWN & HEROiN . GEOLOGY AND ORE DEPOSITS OF TAVOY. 



to unknown. 'This is to some extent due to the slow, but none the 

 less sure, exhaustion of easily won wolfram- bearing quartz from 

 the softer parts of the veins in the uppermost decomposed zone, 

 for there must come a day in the life-history of every vein-mining 

 field when the harder and deeper-seated portions of the deposits 

 have to be exploited if the industry is to continue. The earlier 

 Tavoy tribute system cannot adapt itself to this change and conse- 

 quently fails. It is not proposed to describe here the deep level 

 exploratory work which is now being carried on with the aid of 

 machine drills driven by compressed air; attention has been directed 

 to it in the descriptive section of the report. The leases under which 

 mining areas are held from the Government insist that ore deposits 

 shall be worked and developed in a skilful and workmanlike manner 

 and upon the most approved principles. Both mining leases and 

 mining rules, under the Indian Mines Act, provide for the prepara- 

 tion of large scale mine plans and sections, and for them to be kept 

 up-to-date. The Mines Act Rules have also improved the indi- 

 genous methods of mining by making it unlawful to carry on dan- 

 gerous operations. Finally, the importation of coolies in large 

 numbers both by Government and by private firms has eased the 

 labour shortage to some extent. 



Concentrating Mills. 



Mills for the concentration of wolfram or mixed wolfram and 

 cassiterite ores have been erected at Kanbauk, Pagaye, Widnes 

 and Paungdaw, while others are in contemplation for other mines. 

 Unfortunately, the latter two were only completed about June 

 1919, and no results are available as to their performances at the 

 time of writing. 



Kanbauk Mill. — The mine ore is crushed in a stamp battery of 

 10 stamps of 1,100 lbs., dropping 8 inches, and the screen aperture 

 is \ inch. There are 4 Wililey tables of Nos. 5 and 6 types. The 

 installation is driven by a 32 B. H. P. Hornsby-Akroyd engine, 

 assisted by a 12 H. P. portable engine and boiler. In 1910 the 

 crushing operations resulted as follows : — 



Hours run, 259-5 hours per mouth or 35-4-per cent. only. 



Mine nil' crushed, l>, 075-0 tons. 



Mi. Hock crushed, 1.1JU0-4 tons. ( Vauie £ per cent. ) 



Total oro crushed, 7,67(5 tons. 



Stamp duty 5-8 tons. 



