57. (1) Prisoners under sentence of transportation may, subject to any rules made under section 59, be confined in fetters for the first three months after admission to prison.(2) Should the Superintendent consider it necessary, either for the safe custody of the prisoner himself or for any other reason, that fetters should be retained on any such prisoner for more than three months, he shall apply to the Inspector General for sanction to their retention for the period for which he considers their retention necessary, and the Inspector General may sanction such retention accordingly.