Section 7. The recorder shall be under the direction of the chief justice of the land court division and shall have the custody and control of all papers and documents filed with him in any complaint for registration, action or proceeding in said court, and shall carefully number and index them. Said papers and documents may be kept in Boston in the recorder's office, which shall be near the land court. He may, with the approval of the chief justice of the land court department, employ necessary assistants and messengers.