For the person looking for birth certificates, the Ohio Historical Society says records between 1867 and 1908 were kept by the county probate courts. If you go to http://www.ohiohistory.org/resource/archlib/brthdth1.html you can find the phone number for the Pickaway Co. probate court in Circleville. You might also try the Pickaway Historical Society, which will do searches including court records for $15.