Before any franchise to build any bridge across any such navigable stream is granted by any city or town council it shall fix a license tax, not to exceed ten percent of the tolls collected annually. Upon the completion of the bridge the city or town council shall cause it to be inspected and if it is found to comply in all respects with the specifications previously made, and to be safe and convenient for the public, the council shall declare it open as a toll bridge, and shall immediately fix the rates of toll thereof.