The board of county commissioners, when they deem it necessary, may direct the register of deeds to transcribe and index such of the books in the register’s office as from decay or other cause may require to be transcribed and indexed. They may allow him such compensation at the expense of the county for this work as they think just. The books when so transcribed and approved by the board shall be public records as the original books, and copies therefrom may be certified accordingly. (1868, c. 35, s. 12; Code, s. 3662; Rev., s. 2661; C.S., s. 3557.)