Richard,
My list indicates six cannon in Springfield Ohio, all are Parrott rifles with four being of 3.67" diameter bore and the final two are 4.2" bore diameter. The 3.67" are also referred to as 20 pound Parrotts and the 4.2" as a 30 pounder rifle. All six are in a cemetery in Springfield. Do not have any other information about another cannon in Springfield. You could visit the guns and read the marking on the muzzle and the trunnions. With this information, perhaps we could provide more info.
Ron