If any fire warden, being in need of assistance in the suppression of fire, shall call upon any person to render assistance, and such person shall refuse without a just and fair excuse he shall, upon conviction in a summary proceeding before any magistrate, alderman, or justice of the peace, be sentenced to pay a fine not exceeding one hundred dollars, and, in default of the payment of such fine and costs, be imprisoned in the county jail one day for each dollar of fine and costs unpaid, not, however, exceeding thirty days.