Section 15. For section 31 of the principal Act, the following section shall be substituted, namely:

15. For section 31 of the principal Act, the following section shall be substituted, namely:— "31. (1) No adult employed below ground in a mine shall be allowed to work for more than forty-eight hours in any week or for more than eight hours in any day: Provided that, subject to the previous approval of the Chief Inspector, the daily maximum hours specified in this sub-section may be exceeded in order to facilitate the change of shifts. (2) No work shall be carried on below ground in any mine except by a system of shifts so arranged that the period of work for each shift is not spread over more than the daily maximum hours stipulated in sub-section (1). (3) No person employed in a mine shall be allowed to be present in any part of a mine below ground except during the periods of work shown in respect of him in the register maintained under sub-section (4) of section 48."