Bulletin, Utgave 277

Forside
U.S. Government Printing Office, 1928

Inni boken

Hva folk mener - Skriv en omtale

Vi har ikke funnet noen omtaler på noen av de vanlige stedene.

Andre utgaver - Vis alle

Vanlige uttrykk og setninger

Populære avsnitt

Side 39 - Therefore, it is not. possible to lay down a hard and fast rule that will apply to all the different conditions and characters of coal dusts found in the mines of the United States.
Side 53 - That detonators — preferably electric detonators — are used of not less efficiency than those prescribed, namely, those consisting by weight of 90 parts of mercury fulminate and 10 parts of potassium chlorate (or their equivalents).
Side 43 - ... per cent for each 1 per cent of gas. Where rock dust barriers are installed, the amount of dust used shall be at least 100 pounds per square foot of average cross section of entry, at the barrier zone. 7. Sampling Dust: After a mine, or any part of a mine has been...
Side 43 - A written record shall be entered in a book kept for that purpose in the mine office, showing the location at which samples have been taken, and the results of the analyses.
Side 53 - ... 3. That the explosive, if frozen, shall be thoroughly thawed in a safe and suitable manner before use.
Side 23 - ... the 4,000-foot section or area, a pillar shall be left of sufficient width to permit the driving of the two additional passageways. Separated pairs of parallel entries entering such area, properly maintained, will fulfill the foregoing requirements; and if coal on leased land is to be mined from a mine already existing either on public domain or on private land and in the opinion of the district mining supervisor the ventilation passageways and escapeways are adequate, said requirements may be...
Side 42 - It shall not contain more than 5 per cent of combustible matter, nor more than 25 per cent of quartz or free silica particles, nor absorb moisture from the air to such an extent as to cake and destroy its effectiveness as a dry dust. It may be made from limestone, dolomite, gypsum, anhydrite, shale, talc, adobe, or other inert material which meets the foregoing specifications.
Side 42 - ... working place in the section of the mine which it has been ventilating since leaving the intake to the point of union with the main return. "Exposed electric circuits" means any conductor or conductors of the electric circuit in the mine, other than trailing cables of permissible machines. which by virtue of their location are liable to be damaged by falls of roof, wrecks, etc., which may cause sparks or arcs in the mine atmosphere. An "isolated panel...
Side 22 - In every mine the lessee shall provide an escapeway or second means of egress to the surface, which, if a drift, slope, or tunnel exit, shall be separated at the surface from the first exit by not less than 50 feet of rock or coal in place; if either is a shaft or both are shafts, the exits shall be not less than 200 feet apart.
Side 22 - ... in proper condition for use. If such adjoining mine shall be abandoned at any time, or shall cease to operate indefinitely, the lessee hereunder shall be solely responsible for the cost and expense of maintaining such outlet, and in the event such outlet shall be abandoned or permitted to become unsafe for use, the number of men employed on any one shift shall be reduced below ten until such time as a second exit or escapeway shall be provided.

Bibliografisk informasjon