THE MINERAL DEPTHS 



shut down, upon the breaking out of the war, the water 

 rose so rapidly that it was impossible to remove the 

 pumps, motors, transformers, etc., and consequently 

 they remained under 500 to 1,000 feet of water. 

 Two and a half years later, when peace was declared 

 in South Africa, the water in the shaft was pumped out 

 and the electrical apparatus was removed to the sur- 

 face. Three of the motors were stripped and completely 

 rewound, but to the general surprise of the experts 

 the condition of the insulation indicated that the re- 

 winding might not be absolutely necessary. Accord- 

 ingly the other nine motors were thoroughly dried in 

 an oven and then soaked in oil. After this treatment 

 they were rigidly tested, proved to be all right, and were 

 at once restored to regular service in the mine. The 

 transformers were treated in the same manner as the 

 motors, with equally gratifying results. 



"An interesting illustration of the flexibility and 

 adaptability of electric motors for pumping purposes 

 is furnished by the Gneisenau mine, near Dortmund, 

 Germany, where a very large electric mining plant 

 was installed in 1903. In this instance the pump is 

 located more than 1,200 feet below the surface, and the 

 difficulties of installing the apparatus were so great, 

 on account of the small cross section of the shaft, that 

 it was necessary to build up the motor in the pumping 

 chamber, the material being transported through the 

 wet shaft and the winding of the coils being performed 

 in situ. 



"An interesting use of the electric pump associated 

 with the telephone in connection with mining is noted 



[265] 



