Technical paper . A. VIEW SHOWING EFFECT OF LIGHT EXPLOSION ON BOX B. VltW SHOWING EFFECT OF STRONG EXPLOSION ON BOX BARRIER. ROCK-DUST BARRIERS. 27 some of which can be seen hi the illustration. The later method, bywhich eyes are used with hooks in the roof, is preferred to this arrange-ment of hooks inserted in stirrups. THE CONCENTRATED BARRIER. The concentrated barrier, as its name implies, consists principallyof two large but shallow containers of incombustible dust placedoverhead across the entry way and supported near the roof byhinges and catches. The latter in turn are held
Technical paper . A. VIEW SHOWING EFFECT OF LIGHT EXPLOSION ON BOX B. VltW SHOWING EFFECT OF STRONG EXPLOSION ON BOX BARRIER. ROCK-DUST BARRIERS. 27 some of which can be seen hi the illustration. The later method, bywhich eyes are used with hooks in the roof, is preferred to this arrange-ment of hooks inserted in stirrups. THE CONCENTRATED BARRIER. The concentrated barrier, as its name implies, consists principallyof two large but shallow containers of incombustible dust placedoverhead across the entry way and supported near the roof byhinges and catches. The latter in turn are held by a leveragesystem so adjusted that the system is released when the pressure ofan advancing air wave, operating against swinging vanes, reaches apredetermined amount. The vanes are hinged planks 100 feet or morefrom the barrier on either side, the pressure being converted into apull by a chain passing around a pulley and transmitted by a strongwire from the chain to the releasing mechanism. When the catches are released the hinged containers swing quicklydownward under t
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectminesandmineralresou
