CHAPTER XII

THE MINERAL DEPTHS

Early mining methods, p. 242--Prospecting and locating mines, p. 243--"Booming," p. 246--Conditions to be considered in mining, p. 248--Dangerous gases in mines, p. 249--Artificial lights and lighting, p. 251--Ventilation and drainage, p. 252--Electric machinery in mining, p. 253--Electric drills, p. 254--Traction in mining, p. 256--Various types of electric motors, p. 257--"Telphers," p. 261--Electric mining pumps, p. 263--Some remarkable demonstrations of durability of electric pumps, p. 265--Electricity in coal mining, p. 266--Electric lighting in mines, p. 269.