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. A facsimile of the seal of the corporation and of the signature of either of said officers, but not both of them, may be impressed on the bonds in lieu of their manually signing the same.
Coupons shall be signed by the chairman or vice-chairman of the corporation, but a facsimile of the signature of such chairman or such vice-chairman may be impressed on any such coupons in lieu of his manually signing the same. Bonds so executed shall be valid and may be delivered, notwithstanding any changes in the officers or the seal of the corporation after the signing and sealing of the bonds.