If the qualified electors petitioning for the creation and organization of a separate road district shall so desire, they may petition, in addition, that the proceeds of the sale of said bonds may be used to extend and build roads beyond the limits of such district and that a tax be levied on such district or districts to pay such bonds and maintain such roads, in which case it shall be the duty of the board, in publishing the notice as hereinbefore provided, to add thereto notice of the further purpose to use part of the proceeds of said bonds in building and maintaining roads in other territory, naming the said other territory; and to levy taxes for that purpose. In any election ordered therein, the further question shall be submitted to the electors, whether such roads are to be so extended or not, which shall be submitted as follows: "For the extension of roads into other districts," or "against the extension of roads into other districts." If said election result in favor of such action, determined and adjudicated in like manner by the election commissioners and board of supervisors, as required by law, then the said road commissioners shall, with the approval of the board of supervisors, have the power to extend said roads into other districts and pay for the same out of the proceeds of the sale of said bonds, and levy a tax to maintain the same on such district consenting thereto, as provided for in this chapter.