§ 7. Same—Signatures; seal.

All such bonds shall be signed by the chairman of the authority and attested by the secretary and treasurer of the authority, the official seal of the authority shall be affixed thereto, and any coupons attached thereto shall bear the facsimile signatures of the chairman, and the secretary and treasurer of the authority. Any coupon may bear the facsimile signatures of such persons and any bond may be signed, sealed and attested on behalf of the authority by such person as shall be duly authorized or hold the proper office at the actual time of the execution of such bonds, although, at the date of such bonds, such person may not have been so authorized or shall not have held such office. In case any officer whose signature appears on any coupon ceases to be such officer before delivery of such bonds, such signature shall nevertheless be valid and sufficient for all purposes, the same as if he had remained in office until such delivery.