City Ordinances [of Newburyport], § 15. No person shall fire any rocket, squib, cracker, or other thing formed of gunpowder or other explosive substance, in whole or in part; nor make any bonfire of tar barrels or any other substances, nor, except in the performance of some duty authorized by law, discharge any field piece, gun or other firearm in or upon any street or other way, or upon any wharf or landing within the city.