(1) When any act or omission would, if a person were under a certain age, be an offence punishable under this Act, and such person is in the opinion of the Court prima facie under such age, the burden shall be on the accused to prove that such person is no under such age.
     (2) A declaration in writing by a certifying surgeon relating to a worker that he has personally examined him and believes him to be under the age stated is such declaration shall, for the purposes of this Act and the rules made thereunder, be admissible as evidence of the age of that worker.