All bonds shall be signed by the chairman or vice-chairman of the corporation, and the seal of the corporation shall be affixed thereto and attested by its secretary. Coupons shall be signed by the chairman or vice-chairman of the corporation, but a facsimile of the signature of such chairman or vice-chairman may be impressed on any such interest coupons in lieu of his manually signing the same.
Delivery of bonds so executed shall be valid notwithstanding any changes in officers or in the seal of the corporation after the signing and sealing of the bonds.