The fire limits of the city, encompassing the area hereinafter known as the fire district, shall be the outside limits of the combined business use district and manufacturing and industrial use district, determined from the intersection of Main Street and Lincoln Avenue in the city, and the fire district shall encompass all of both such use districts as such use districts are presently defined by title 17 of this code, or as such use districts may in the future be altered, revised, or changed by appropriate ordinance of the city council or mayor of the city, such alteration, revision or change in such use districts automatically altering the fire limits and fire district so that the fire limits and fire district shall at all times include all territory, streets, intersections and alleyways included inside the business and manufacturing and industrial use districts. (Prior code §6-7)