I would like to learn as much as I can about a large square I picked up. Overall dimensions are approximately 30" X 12". I can't find a brand name on it. The blade part is stamped "Cast Steel" and "Warranted". There are no graduations. The black part appears to have been painted by hand. Would this be used in a particular industry such as shipbuilding? How common are squares this size? How old might it be? Would this be of interest to a collector?