Every person owning or acting as agent for person occupying any building or lot in the city, shall keep or cause the sidewalk adjacent to such building to be kept open and free from ice, snow and all other obstructions, barriers, and impediments of every description: provided the City Engineer, Mayor or Police Chief may permit temporary obstruction to persons in receiving, selling or removing fuel, lumber, boxes or merchandise and all articles of trade if such obstruction be removed within twenty-four (24) hours.