Section 15. The register shall have the care and custody of all books, documents and papers, whether in physical or electronic form, pertaining to his court, or deposited with the records of insolvency or filed in the registry of probate, and shall carefully preserve them and deliver them to his successor. He may, with the approval of the chief justice and at the expense of the commonwealth cause copies of the indexes, or new indexes, to the records which are in his custody, to be printed and sold at a price not less than the cost of paper, printing and binding. He shall perform all other duties, pertaining to his office, required by law or prescribed by the judge. He may attest the records by the volume, and the attestation shall be sufficient when the volume containing the same bears the attest, with the written signature of the register or other person lawfully authorized.