C—3a

30

Subject 3.— Gases of Mines, Spontaneous Combustion, and Ventilation. 1. Name the gases usually met with in coal-mines, with their respective peculiarities. 2. In securing adequate ventilation in a very gaseous mine, what are the chief points fof consideration ? 3. What are the indications of spontaneous combustion ; and, having found a fire resulting from such in a disused part of the mine, how would you deal with it, the safety of the men engaged at the work having the first consideration ? 4. Ventilate the attached plan, using the reference signs thereon to indicate your method. 5. What steps would you take if' you were in charge of a working-district giving off gas and a sudden stoppage of the air-current took place ? 6. If the anemometer registered 350 revolutions per minute in an airway 12 ft. by 7 ft., what total quantity of air would be passing ? 7. What are the advantages of splitting air-currents, and, in your opinion, what is the best way of doing so ?