Any school district issuing bonds under the provisions of this act¹ shall create a sinking fund for the payment of principal and interest of the bonds and any taxes covenanted to be paid thereon. For the purpose of creating such sinking fund the board of public education of the school district of the first class issuing the bonds shall, at or before the time of so doing, provide for the levy of a tax sufficient to pay principal of the bonds within twenty-five years together with the interest thereon and any taxes covenanted to be paid thereon, such tax to be collected annually until payment of said bonds and the interest thereon and any taxes covenanted to be paid thereon be fully met.