Section 39. Power to make exempting rules,—The Central Government may make tulea providing for the exemption, to

39. Power to make exempting rules,—The Central Government may make tulea providing for the exemption, to such extent and subject to such conditions as may be specified, from the. provisions of sections 28, 30, 81, 34 or ijub-aection {4) of section 80,— (a) of all or any of the persons employed in a mine, where vn emergency involving serious risk to the safety of the mine or of the persons employed therein u apprehended; (b) of all or any of the persons BO employed, in case of an accident, actual or apprehended; (c) of all or any of the persons engaged in urgent repairs; anl (d) of all or aiiy of the persons employod in nny work which for technical reasons must be earned on continuously throughout the day