Stone dust barriers
In every gassy seam of the second or third degree[or in the development workings in a gassy seam of the first degree in which there is likelihood of occurrence of inflammable gas in dangerous quantity]additional precautions shall be taken by providing stone dust barriers to prevent an ignition of explosion from extending from one part of the mine the other. Every such stone dust barriers shall be of such a type as may be approved by the Chief Inspector by a general or special order in writing and shall be maintained in such manner as may be specified in the said order : ...