Sec. 20.  Appointment of clerk and treasurer.
   That at the first meeting of the board of commissioners, or as soon thereafter as practicable, they shall elect a town clerk, who shall act as treasurer, and a tax-collector, who shall respectively hold their offices during the term of the board electing them and until their successors are elected and qualified, subject, however, to be removed at any time and others appointed in their stead for misbehavior or neglect in office. Before acting, each of said officers shall take an oath before the mayor to faithfully discharge the duties required of him by the board of commissioners, and each shall execute a bond in such an amount as the board may require, with security to be approved by the board. The bonds required by the clerk and tax-collector shall be renewed every year.