Section 78. Any officer in attendance upon the supreme judicial court in Suffolk county under section seventy-three, including the messenger of the justices of said court, may be designated by the justices to serve venires for jurors and the processes of said court, and when so designated shall have the authority of constables for said purposes, and shall be paid by the commonwealth his actual expenses necessarily incurred in making such services. He shall first give to the commonwealth a bond with sufficient sureties in the sum of fifteen hundred dollars for the faithful performance of his duties.