The height limitations stipulated elsewhere in this Zoning Ordinance shall not apply to the following:
(a) Farm Buildings, Architectural Features, etc. Barns, silos, or other farm buildings or structures on farms; church spires, belfries, cupolas and domes; monuments; water towers, chimneys, smoke stacks, flagpoles; parapet walls extending not more than four feet above the limiting height of the building.
(b) Elevator Penthouses, Water Tanks, etc. Elevator penthouses, water tanks, monitors and scenery lofts, provided no linear dimension of any such structure exceeds fifty percent (50%) of the corresponding street lot line frontage; towers and monuments, fire towers, hose towers, cooling towers, grain elevators, gas holders or other structures where the manufacturing process requires a greater height.