SYMPOSIUM OX COXSERVATIOX 65 



preliminary period of mine development and defer profits three or 

 four years longer than usual. The plan contemplates locating 

 the shaft at the common corner of four sections of land, and 

 cutting haulage ways to one side and thence to a corner. The 

 coal could be completely recovered by retreating long-wall 

 method, and the total cost of mining doubtless would be less than 

 under present methods. The difficulty lies in the fact that two 

 and one-half years would be required to drive the entries and 

 make ready for profitable mining. The heav)' cost during early 

 years would rapidly decrease, and the closing years of mining 

 would be more profitable, in contrast to the reverse conditions 

 under present practice. 



Losses Due to Carelessness in Operation. Besides wastes due 

 to faulty system of mining, careless or inefficient operation is 

 important. Failure to keep maps up-to-date frequently causes 

 small blocks of coal to be passed by until too late for recovery. 

 Surveys are not complete when mines are finally abandoned, and 

 so future operators on adjoining properties are required to leave 

 barriers of unnecessary size in order to be free from danger of 

 gas and water in the abandoned workings. Again, pillars are 

 left so small, or are "robbed"' to such an extent, that roof and 

 floor begin to "squeeze," and the coal is so crushed that large 

 areas are abandoned. Fires, similarly, require the sealing off 

 of large portions of the mines, and recovery is neglected. An- 

 other species of prevailing bad practice is the excessive use of 

 explosives to blast down the coal. This causes an undue amount 

 of fine coal, which either is not loaded out or is of low market 

 value. In addition, this practice causes fatal explosions directly, 

 or so weakens the roof that fatal accidents and the abandonment 

 of parts of the mine follow indirectly. 



Losses Due to Irregular Property Boundaries. A growing 

 source of waste of coal is due to the purchase of land in checker- 

 board fashion, and to similar competitive tactics which isolate 

 areas of coal, which are too small to warrant independent mining. 



\\"aste of Coal by Improper and Unnecessary Utilization. 



Generation of Pozver, Heat, and Light. Although it is difficult 

 for one who is not a mechanical engineer to appreciate the waste- 

 ful utilization of coal, enough has been written on the subject to 

 emphasize certain important features. Thus, the ordinary boiler 

 utilizes only 5 per cent to lo per cent of the fuel energy. Even 



