167. When any sentence of detention is passed under this Act, or when any sentence so passed is commuted to detention, the punishment shall he carried out by detaining the offender in any Military or Air Force detention barracks, detention cells or other Military or Air Force custody, and when the sentence is to be carried out by detention in any Military or Air Force detention barracks, the commanding officer of the person under sentence, or such other officer as may be prescribed, shall forward the person under sentence, together with a warrant in the prescribed form, to the officer in charge of the said detention barracks.