Whoever forges, counterfeits, or fraudulently alters the seal or signature of any person authorised by or under this Act to administer an oath, or tenders in evidence, or otherwise uses, any affidavit having any seal or signature so forged or counterfeited or fraudulently altered, knowing the same to be forged, counterfeited, or fraudulently altered, shall be guilty of felony, and liable on conviction to penal servitude for any term not exceeding seven years and not less than five years, or to imprisonment . . . F1 for any term not exceeding two years.