Section 47. No fees shall be allowed upon the return of an officer upon a precept in a criminal case, in which expenses are charged, unless every item of expense incurred and the name of the person to whom each amount was paid is set forth under oath in the return; and no item of expense which may be considered unreasonable shall be allowed by the court without satisfactory proof that the expense was necessarily incurred and the amount reasonable. But the superior court, with the written approval of the district attorney, or a district court or a trial justice, may, upon the petition of an officer named in sections fifty and fifty-one, allow extra compensation for any meritorious service for which the fees allowed by law are manifestly inadequate. No allowance shall be made for aid in the service of a mittimus, unless first authorized in writing by the court which issues it. Justices, clerks and assistant clerks of courts shall administer the oath to officers upon their returns, at their request; and no fee shall be allowed to an officer for such oath, and no justice of the peace shall be entitled to a fee for administering such oath.