Sec. 19. No person shall fire or discharge any cannon, gun, fowling piece, pistol or firearms of any description, or fire, explode or set off any squib, cracker or other thing containing powder or other combustible or explosive material, or set off or exhibit any fireworks, within the limits of the City of Superior, without first having obtained written permission from the mayor, which permission shall limit the time and fix the place of such firing, and be subject to be revoked at any time after the same may have been granted. Any person who shall violate any provision of this section shall, upon conviction thereof, be punished by a fine of not less than one (1) dollar nor more than fifty (50) dollars for each offense; but this section shall not be construed to prohibit the discharge of firearms when done in the lawful defense of person or property, or family, or in the necessary enforcement of the law; nor to prohibit shot-gun practice upon the grounds used by any gun club for such purpose.