1. To barns, silos, or other farm buildings or structures on farms, provided these are not less than 50 feet from every lot line; to church spires, belfries, cupolas, and domes, monuments, water towers, fire and hose towers, masts, and aerials; to parapet walls extending not more than four feet above the limiting height of the building. However, if in the opinion of the Building and Zoning Enforcement Officer, such structure would adversely affect adjoining or adjacent properties, such greater height will not be authorized except by the Board of Adjustment; to bulkheads, conveyors, derricks, elevator penthouses, water tanks, monitors, and scenery lofts; to cooling towers, grain elevators, gas holders, or other structures; or where a manufacturing process requires a greater height than specified, such may be authorized by the Board of Adjustment.