Section 15. The town clerk shall record all votes passed at town meetings held during his term of office. He shall administer the oaths of office to all town officers who apply to him to be sworn, and shall make a record thereof and of the oaths of office taken before justices of the peace of which certificates are filed. He shall, immediately after every annual election of town officers, transmit to the state secretary, on blanks to be furnished by him, a complete list of all town officers elected and qualified and shall promptly report to the secretary any changes in such officers. He shall, except in the county of Suffolk, within seven days after the qualification of a constable make return of his name to the clerk of the courts and to the sheriff of the county. He shall make and keep an index of instruments entered with him required by law to be recorded, which shall be divided into five columns, with appropriate headings for recording the date of reception, the names of parties and the book and page on which each instrument is recorded. It shall be open to public inspection.