Each bond or other evidence of indebtedness issued by the city shall contain on its face a statement specifying the purpose for which it is issued. The use of the proceeds for any other purpose shall be unlawful. All bonds or other evidences of indebtedness shall be signed by the Mayor and countersigned by the Clerk under the seal of the city. Interest coupons may be executed with the facsimile signature of the Mayor and the Clerk. The Clerk shall keep a complete and detailed record of all bonds and other evidences of indebtedness issued by the city. Upon payment, the respective bond or other evidence of indebtedness shall be canceled.