Whoever, being legally bound by an oath 1[or affirmation] to state the truth on any subject to any public servant or other person authorized by law to administer such oath [or affirmation], makes, to such public servant or other person as aforesaid, touching that subject, any statement which is false, and which he either knows or believes to be false or does not believe to be true, shall be punished with imprisonment of either description for a term which may extend to three years, and shall also be liable to fine.