The period of time of a public auction of jewelry shall not exceed thirty days, Sunday and legal holidays excluded; provided, that if it shall be made to appear upon sworn application to the city clerk at any time during the period of thirty days, that all the jewelry described and inventoried in the original application has not been sold, accompanied by a statement or inventory of what remains thereof, a permit supplemental to that provided for may be issued by the city clerk upon the same terms and conditions as the original permit, granting authority to continue such sale for a further period of thirty days. (Ord. No. 462, § 3.)