In any case in which the inhabitants of any certified township, or any of the subdivisions of such certified township, including any borough or boroughs that have been erected within the original boundaries, of this commonwealth, being the owners of land within the same, are authorized by law to meet at the place of holding elections in such township and elect trustees for the proprietor of public lands therein, and, being so authorized, have heretofore met at a place for holding general elections in such township and have elected trustees for the proprietors of public lands therein, such election shall be and is hereby declared to be valid; and the trustees so elected are declared to be the legal trustees for the proprietors, of such certified township, notwithstanding the fact that such township has been divided, or that a borough or boroughs have been erected within the original boundaries thereof, or that the number of places for holding general elections therein has been increased since the enactment of the law authorizing the election of such trustees: Provided, That such election or elections, hereby validated, shall have been held at a place of holding general elections located within the original boundaries of such certified township, and that notice of the holding thereof shall have been given in substantial compliance with the law authorizing such elections.